src/insert.c

/*
** 2001 September 15
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains C code routines that are called by the parser
** to handle INSERT statements in SQLite.
*/
#include "sqliteInt.h"

/*
** Generate code that will 
**
**   (1) acquire a lock for table pTab then
**   (2) open pTab as cursor iCur.
**
** If pTab is a WITHOUT ROWID table, then it is the PRIMARY KEY index
** for that table that is actually opened.
*/
void sqlite3OpenTable(
  Parse *pParse,  /* Generate code into this VDBE */
  int iCur,       /* The cursor number of the table */
  int iDb,        /* The database index in sqlite3.aDb[] */
  Table *pTab,    /* The table to be opened */
  int opcode      /* OP_OpenRead or OP_OpenWrite */
){
  Vdbe *v;
  assert( !IsVirtual(pTab) );
  v = sqlite3GetVdbe(pParse);
  assert( opcode==OP_OpenWrite || opcode==OP_OpenRead );
  sqlite3TableLock(pParse, iDb, pTab->tnum, 
                   (opcode==OP_OpenWrite)?1:0, pTab->zName);
  if( HasRowid(pTab) ){
    sqlite3VdbeAddOp4Int(v, opcode, iCur, pTab->tnum, iDb, pTab->nCol);
    VdbeComment((v, "%s", pTab->zName));
  }else{
    Index *pPk = sqlite3PrimaryKeyIndex(pTab);
    assert( pPk!=0 );
    assert( pPk->tnum==pTab->tnum );
    sqlite3VdbeAddOp3(v, opcode, iCur, pPk->tnum, iDb);
    sqlite3VdbeSetP4KeyInfo(pParse, pPk);
    VdbeComment((v, "%s", pTab->zName));
  }
}

/*
** Return a pointer to the column affinity string associated with index
** pIdx. A column affinity string has one character for each column in 
** the table, according to the affinity of the column:
**
**  Character      Column affinity
**  ------------------------------
**  'A'            BLOB
**  'B'            TEXT
**  'C'            NUMERIC
**  'D'            INTEGER
**  'F'            REAL
**
** An extra 'D' is appended to the end of the string to cover the
** rowid that appears as the last column in every index.
**
** Memory for the buffer containing the column index affinity string
** is managed along with the rest of the Index structure. It will be
** released when sqlite3DeleteIndex() is called.
*/
const char *sqlite3IndexAffinityStr(sqlite3 *db, Index *pIdx){
  if( !pIdx->zColAff ){
    /* The first time a column affinity string for a particular index is
    ** required, it is allocated and populated here. It is then stored as
    ** a member of the Index structure for subsequent use.
    **
    ** The column affinity string will eventually be deleted by
    ** sqliteDeleteIndex() when the Index structure itself is cleaned
    ** up.
    */
    int n;
    Table *pTab = pIdx->pTable;
    pIdx->zColAff = (char *)sqlite3DbMallocRaw(0, pIdx->nColumn+1);
    if( !pIdx->zColAff ){
      sqlite3OomFault(db);
      return 0;
    }
    for(n=0; n<pIdx->nColumn; n++){
      i16 x = pIdx->aiColumn[n];
      char aff;
      if( x>=0 ){
        aff = pTab->aCol[x].affinity;
      }else if( x==XN_ROWID ){
        aff = SQLITE_AFF_INTEGER;
      }else{
        assert( x==XN_EXPR );
        assert( pIdx->aColExpr!=0 );
        aff = sqlite3ExprAffinity(pIdx->aColExpr->a[n].pExpr);
      }
      if( aff<SQLITE_AFF_BLOB ) aff = SQLITE_AFF_BLOB;
      if( aff>SQLITE_AFF_NUMERIC) aff = SQLITE_AFF_NUMERIC;
      pIdx->zColAff[n] = aff;
    }
    pIdx->zColAff[n] = 0;
  }
 
  return pIdx->zColAff;
}

/*
** Compute the affinity string for table pTab, if it has not already been
** computed.  As an optimization, omit trailing SQLITE_AFF_BLOB affinities.
**
** If the affinity exists (if it is no entirely SQLITE_AFF_BLOB values) and
** if iReg>0 then code an OP_Affinity opcode that will set the affinities
** for register iReg and following.  Or if affinities exists and iReg==0,
** then just set the P4 operand of the previous opcode (which should  be
** an OP_MakeRecord) to the affinity string.
**
** A column affinity string has one character per column:
**
**  Character      Column affinity
**  ------------------------------
**  'A'            BLOB
**  'B'            TEXT
**  'C'            NUMERIC
**  'D'            INTEGER
**  'E'            REAL
*/
void sqlite3TableAffinity(Vdbe *v, Table *pTab, int iReg){
  int i;
  char *zColAff = pTab->zColAff;
  if( zColAff==0 ){
    sqlite3 *db = sqlite3VdbeDb(v);
    zColAff = (char *)sqlite3DbMallocRaw(0, pTab->nCol+1);
    if( !zColAff ){
      sqlite3OomFault(db);
      return;
    }

    for(i=0; i<pTab->nCol; i++){
      assert( pTab->aCol[i].affinity!=0 );
      zColAff[i] = pTab->aCol[i].affinity;
    }
    do{
      zColAff[i--] = 0;
    }while( i>=0 && zColAff[i]<=SQLITE_AFF_BLOB );
    pTab->zColAff = zColAff;
  }
  assert( zColAff!=0 );
  i = sqlite3Strlen30NN(zColAff);
  if( i ){
    if( iReg ){
      sqlite3VdbeAddOp4(v, OP_Affinity, iReg, i, 0, zColAff, i);
    }else{
      sqlite3VdbeChangeP4(v, -1, zColAff, i);
    }
  }
}

/*
** Return non-zero if the table pTab in database iDb or any of its indices
** have been opened at any point in the VDBE program. This is used to see if 
** a statement of the form  "INSERT INTO <iDb, pTab> SELECT ..." can 
** run without using a temporary table for the results of the SELECT. 
*/
static int readsTable(Parse *p, int iDb, Table *pTab){
  Vdbe *v = sqlite3GetVdbe(p);
  int i;
  int iEnd = sqlite3VdbeCurrentAddr(v);
#ifndef SQLITE_OMIT_VIRTUALTABLE
  VTable *pVTab = IsVirtual(pTab) ? sqlite3GetVTable(p->db, pTab) : 0;
#endif

  for(i=1; i<iEnd; i++){
    VdbeOp *pOp = sqlite3VdbeGetOp(v, i);
    assert( pOp!=0 );
    if( pOp->opcode==OP_OpenRead && pOp->p3==iDb ){
      Index *pIndex;
      int tnum = pOp->p2;
      if( tnum==pTab->tnum ){
        return 1;
      }
      for(pIndex=pTab->pIndex; pIndex; pIndex=pIndex->pNext){
        if( tnum==pIndex->tnum ){
          return 1;
        }
      }
    }
#ifndef SQLITE_OMIT_VIRTUALTABLE
    if( pOp->opcode==OP_VOpen && pOp->p4.pVtab==pVTab ){
      assert( pOp->p4.pVtab!=0 );
      assert( pOp->p4type==P4_VTAB );
      return 1;
    }
#endif
  }
  return 0;
}

#ifndef SQLITE_OMIT_AUTOINCREMENT
/*
** Locate or create an AutoincInfo structure associated with table pTab
** which is in database iDb.  Return the register number for the register
** that holds the maximum rowid.  Return zero if pTab is not an AUTOINCREMENT
** table.  (Also return zero when doing a VACUUM since we do not want to
** update the AUTOINCREMENT counters during a VACUUM.)
**
** There is at most one AutoincInfo structure per table even if the
** same table is autoincremented multiple times due to inserts within
** triggers.  A new AutoincInfo structure is created if this is the
** first use of table pTab.  On 2nd and subsequent uses, the original
** AutoincInfo structure is used.
**
** Four consecutive registers are allocated:
**
**   (1)  The name of the pTab table.
**   (2)  The maximum ROWID of pTab.
**   (3)  The rowid in sqlite_sequence of pTab
**   (4)  The original value of the max ROWID in pTab, or NULL if none
**
** The 2nd register is the one that is returned.  That is all the
** insert routine needs to know about.
*/
static int autoIncBegin(
  Parse *pParse,      /* Parsing context */
  int iDb,            /* Index of the database holding pTab */
  Table *pTab         /* The table we are writing to */
){
  int memId = 0;      /* Register holding maximum rowid */
  assert( pParse->db->aDb[iDb].pSchema!=0 );
  if( (pTab->tabFlags & TF_Autoincrement)!=0
   && (pParse->db->mDbFlags & DBFLAG_Vacuum)==0
  ){
    Parse *pToplevel = sqlite3ParseToplevel(pParse);
    AutoincInfo *pInfo;
    Table *pSeqTab = pParse->db->aDb[iDb].pSchema->pSeqTab;

    /* Verify that the sqlite_sequence table exists and is an ordinary
    ** rowid table with exactly two columns.
    ** Ticket d8dc2b3a58cd5dc2918a1d4acb 2018-05-23 */
    if( pSeqTab==0
     || !HasRowid(pSeqTab)
     || IsVirtual(pSeqTab)
     || pSeqTab->nCol!=2
    ){
      pParse->nErr++;
      pParse->rc = SQLITE_CORRUPT_SEQUENCE;
      return 0;
    }

    pInfo = pToplevel->pAinc;
    while( pInfo && pInfo->pTab!=pTab ){ pInfo = pInfo->pNext; }
    if( pInfo==0 ){
      pInfo = sqlite3DbMallocRawNN(pParse->db, sizeof(*pInfo));
      if( pInfo==0 ) return 0;
      pInfo->pNext = pToplevel->pAinc;
      pToplevel->pAinc = pInfo;
      pInfo->pTab = pTab;
      pInfo->iDb = iDb;
      pToplevel->nMem++;                  /* Register to hold name of table */
      pInfo->regCtr = ++pToplevel->nMem;  /* Max rowid register */
      pToplevel->nMem +=2;       /* Rowid in sqlite_sequence + orig max val */
    }
    memId = pInfo->regCtr;
  }
  return memId;
}

/*
** This routine generates code that will initialize all of the
** register used by the autoincrement tracker.  
*/
void sqlite3AutoincrementBegin(Parse *pParse){
  AutoincInfo *p;            /* Information about an AUTOINCREMENT */
  sqlite3 *db = pParse->db;  /* The database connection */
  Db *pDb;                   /* Database only autoinc table */
  int memId;                 /* Register holding max rowid */
  Vdbe *v = pParse->pVdbe;   /* VDBE under construction */

  /* This routine is never called during trigger-generation.  It is
  ** only called from the top-level */
  assert( pParse->pTriggerTab==0 );
  assert( sqlite3IsToplevel(pParse) );

  assert( v );   /* We failed long ago if this is not so */
  for(p = pParse->pAinc; p; p = p->pNext){
    static const int iLn = VDBE_OFFSET_LINENO(2);
    static const VdbeOpList autoInc[] = {
      /* 0  */ {OP_Null,    0,  0, 0},
      /* 1  */ {OP_Rewind,  0, 10, 0},
      /* 2  */ {OP_Column,  0,  0, 0},
      /* 3  */ {OP_Ne,      0,  9, 0},
      /* 4  */ {OP_Rowid,   0,  0, 0},
      /* 5  */ {OP_Column,  0,  1, 0},
      /* 6  */ {OP_AddImm,  0,  0, 0},
      /* 7  */ {OP_Copy,    0,  0, 0},
      /* 8  */ {OP_Goto,    0, 11, 0},
      /* 9  */ {OP_Next,    0,  2, 0},
      /* 10 */ {OP_Integer, 0,  0, 0},
      /* 11 */ {OP_Close,   0,  0, 0} 
    };
    VdbeOp *aOp;
    pDb = &db->aDb[p->iDb];
    memId = p->regCtr;
    assert( sqlite3SchemaMutexHeld(db, 0, pDb->pSchema) );
    sqlite3OpenTable(pParse, 0, p->iDb, pDb->pSchema->pSeqTab, OP_OpenRead);
    sqlite3VdbeLoadString(v, memId-1, p->pTab->zName);
    aOp = sqlite3VdbeAddOpList(v, ArraySize(autoInc), autoInc, iLn);
    if( aOp==0 ) break;
    aOp[0].p2 = memId;
    aOp[0].p3 = memId+2;
    aOp[2].p3 = memId;
    aOp[3].p1 = memId-1;
    aOp[3].p3 = memId;
    aOp[3].p5 = SQLITE_JUMPIFNULL;
    aOp[4].p2 = memId+1;
    aOp[5].p3 = memId;
    aOp[6].p1 = memId;
    aOp[7].p2 = memId+2;
    aOp[7].p1 = memId;
    aOp[10].p2 = memId;
    if( pParse->nTab==0 ) pParse->nTab = 1;
  }
}

/*
** Update the maximum rowid for an autoincrement calculation.
**
** This routine should be called when the regRowid register holds a
** new rowid that is about to be inserted.  If that new rowid is
** larger than the maximum rowid in the memId memory cell, then the
** memory cell is updated.
*/
static void autoIncStep(Parse *pParse, int memId, int regRowid){
  if( memId>0 ){
    sqlite3VdbeAddOp2(pParse->pVdbe, OP_MemMax, memId, regRowid);
  }
}

/*
** This routine generates the code needed to write autoincrement
** maximum rowid values back into the sqlite_sequence register.
** Every statement that might do an INSERT into an autoincrement
** table (either directly or through triggers) needs to call this
** routine just before the "exit" code.
*/
static SQLITE_NOINLINE void autoIncrementEnd(Parse *pParse){
  AutoincInfo *p;
  Vdbe *v = pParse->pVdbe;
  sqlite3 *db = pParse->db;

  assert( v );
  for(p = pParse->pAinc; p; p = p->pNext){
    static const int iLn = VDBE_OFFSET_LINENO(2);
    static const VdbeOpList autoIncEnd[] = {
      /* 0 */ {OP_NotNull,     0, 2, 0},
      /* 1 */ {OP_NewRowid,    0, 0, 0},
      /* 2 */ {OP_MakeRecord,  0, 2, 0},
      /* 3 */ {OP_Insert,      0, 0, 0},
      /* 4 */ {OP_Close,       0, 0, 0}
    };
    VdbeOp *aOp;
    Db *pDb = &db->aDb[p->iDb];
    int iRec;
    int memId = p->regCtr;

    iRec = sqlite3GetTempReg(pParse);
    assert( sqlite3SchemaMutexHeld(db, 0, pDb->pSchema) );
    sqlite3VdbeAddOp3(v, OP_Le, memId+2, sqlite3VdbeCurrentAddr(v)+7, memId);
    VdbeCoverage(v);
    sqlite3OpenTable(pParse, 0, p->iDb, pDb->pSchema->pSeqTab, OP_OpenWrite);
    aOp = sqlite3VdbeAddOpList(v, ArraySize(autoIncEnd), autoIncEnd, iLn);
    if( aOp==0 ) break;
    aOp[0].p1 = memId+1;
    aOp[1].p2 = memId+1;
    aOp[2].p1 = memId-1;
    aOp[2].p3 = iRec;
    aOp[3].p2 = iRec;
    aOp[3].p3 = memId+1;
    aOp[3].p5 = OPFLAG_APPEND;
    sqlite3ReleaseTempReg(pParse, iRec);
  }
}
void sqlite3AutoincrementEnd(Parse *pParse){
  if( pParse->pAinc ) autoIncrementEnd(pParse);
}
#else
/*
** If SQLITE_OMIT_AUTOINCREMENT is defined, then the three routines
** above are all no-ops
*/
# define autoIncBegin(A,B,C) (0)
# define autoIncStep(A,B,C)
#endif /* SQLITE_OMIT_AUTOINCREMENT */


/* Forward declaration */
static int xferOptimization(
  Parse *pParse,        /* Parser context */
  Table *pDest,         /* The table we are inserting into */
  Select *pSelect,      /* A SELECT statement to use as the data source */
  int onError,          /* How to handle constraint errors */
  int iDbDest           /* The database of pDest */
);

/*
** This routine is called to handle SQL of the following forms:
**
**    insert into TABLE (IDLIST) values(EXPRLIST),(EXPRLIST),...
**    insert into TABLE (IDLIST) select
**    insert into TABLE (IDLIST) default values
**
** The IDLIST following the table name is always optional.  If omitted,
** then a list of all (non-hidden) columns for the table is substituted.
** The IDLIST appears in the pColumn parameter.  pColumn is NULL if IDLIST
** is omitted.
**
** For the pSelect parameter holds the values to be inserted for the
** first two forms shown above.  A VALUES clause is really just short-hand
** for a SELECT statement that omits the FROM clause and everything else
** that follows.  If the pSelect parameter is NULL, that means that the
** DEFAULT VALUES form of the INSERT statement is intended.
**
** The code generated follows one of four templates.  For a simple
** insert with data coming from a single-row VALUES clause, the code executes
** once straight down through.  Pseudo-code follows (we call this
** the "1st template"):
**
**         open write cursor to <table> and its indices
**         put VALUES clause expressions into registers
**         write the resulting record into <table>
**         cleanup
**
** The three remaining templates assume the statement is of the form
**
**   INSERT INTO <table> SELECT ...
**
** If the SELECT clause is of the restricted form "SELECT * FROM <table2>" -
** in other words if the SELECT pulls all columns from a single table
** and there is no WHERE or LIMIT or GROUP BY or ORDER BY clauses, and
** if <table2> and <table1> are distinct tables but have identical
** schemas, including all the same indices, then a special optimization
** is invoked that copies raw records from <table2> over to <table1>.
** See the xferOptimization() function for the implementation of this
** template.  This is the 2nd template.
**
**         open a write cursor to <table>
**         open read cursor on <table2>
**         transfer all records in <table2> over to <table>
**         close cursors
**         foreach index on <table>
**           open a write cursor on the <table> index
**           open a read cursor on the corresponding <table2> index
**           transfer all records from the read to the write cursors
**           close cursors
**         end foreach
**
** The 3rd template is for when the second template does not apply
** and the SELECT clause does not read from <table> at any time.
** The generated code follows this template:
**
**         X <- A
**         goto B
**      A: setup for the SELECT
**         loop over the rows in the SELECT
**           load values into registers R..R+n
**           yield X
**         end loop
**         cleanup after the SELECT
**         end-coroutine X
**      B: open write cursor to <table> and its indices
**      C: yield X, at EOF goto D
**         insert the select result into <table> from R..R+n
**         goto C
**      D: cleanup
**
** The 4th template is used if the insert statement takes its
** values from a SELECT but the data is being inserted into a table
** that is also read as part of the SELECT.  In the third form,
** we have to use an intermediate table to store the results of
** the select.  The template is like this:
**
**         X <- A
**         goto B
**      A: setup for the SELECT
**         loop over the tables in the SELECT
**           load value into register R..R+n
**           yield X
**         end loop
**         cleanup after the SELECT
**         end co-routine R
**      B: open temp table
**      L: yield X, at EOF goto M
**         insert row from R..R+n into temp table
**         goto L
**      M: open write cursor to <table> and its indices
**         rewind temp table
**      C: loop over rows of intermediate table
**           transfer values form intermediate table into <table>
**         end loop
**      D: cleanup
*/
void sqlite3Insert(
  Parse *pParse,        /* Parser context */
  SrcList *pTabList,    /* Name of table into which we are inserting */
  Select *pSelect,      /* A SELECT statement to use as the data source */
  IdList *pColumn,      /* Column names corresponding to IDLIST. */
  int onError,          /* How to handle constraint errors */
  Upsert *pUpsert       /* ON CONFLICT clauses for upsert, or NULL */
){
  sqlite3 *db;          /* The main database structure */
  Table *pTab;          /* The table to insert into.  aka TABLE */
  int i, j;             /* Loop counters */
  Vdbe *v;              /* Generate code into this virtual machine */
  Index *pIdx;          /* For looping over indices of the table */
  int nColumn;          /* Number of columns in the data */
  int nHidden = 0;      /* Number of hidden columns if TABLE is virtual */
  int iDataCur = 0;     /* VDBE cursor that is the main data repository */
  int iIdxCur = 0;      /* First index cursor */
  int ipkColumn = -1;   /* Column that is the INTEGER PRIMARY KEY */
  int endOfLoop;        /* Label for the end of the insertion loop */
  int srcTab = 0;       /* Data comes from this temporary cursor if >=0 */
  int addrInsTop = 0;   /* Jump to label "D" */
  int addrCont = 0;     /* Top of insert loop. Label "C" in templates 3 and 4 */
  SelectDest dest;      /* Destination for SELECT on rhs of INSERT */
  int iDb;              /* Index of database holding TABLE */
  u8 useTempTable = 0;  /* Store SELECT results in intermediate table */
  u8 appendFlag = 0;    /* True if the insert is likely to be an append */
  u8 withoutRowid;      /* 0 for normal table.  1 for WITHOUT ROWID table */
  u8 bIdListInOrder;    /* True if IDLIST is in table order */
  ExprList *pList = 0;  /* List of VALUES() to be inserted  */

  /* Register allocations */
  int regFromSelect = 0;/* Base register for data coming from SELECT */
  int regAutoinc = 0;   /* Register holding the AUTOINCREMENT counter */
  int regRowCount = 0;  /* Memory cell used for the row counter */
  int regIns;           /* Block of regs holding rowid+data being inserted */
  int regRowid;         /* registers holding insert rowid */
  int regData;          /* register holding first column to insert */
  int *aRegIdx = 0;     /* One register allocated to each index */

#ifndef SQLITE_OMIT_TRIGGER
  int isView;                 /* True if attempting to insert into a view */
  Trigger *pTrigger;          /* List of triggers on pTab, if required */
  int tmask;                  /* Mask of trigger times */
#endif

  db = pParse->db;
  if( pParse->nErr || db->mallocFailed ){
    goto insert_cleanup;
  }
  dest.iSDParm = 0;  /* Suppress a harmless compiler warning */

  /* If the Select object is really just a simple VALUES() list with a
  ** single row (the common case) then keep that one row of values
  ** and discard the other (unused) parts of the pSelect object
  */
  if( pSelect && (pSelect->selFlags & SF_Values)!=0 && pSelect->pPrior==0 ){
    pList = pSelect->pEList;
    pSelect->pEList = 0;
    sqlite3SelectDelete(db, pSelect);
    pSelect = 0;
  }

  /* Locate the table into which we will be inserting new information.
  */
  assert( pTabList->nSrc==1 );
  pTab = sqlite3SrcListLookup(pParse, pTabList);
  if( pTab==0 ){
    goto insert_cleanup;
  }
  iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
  assert( iDb<db->nDb );
  if( sqlite3AuthCheck(pParse, SQLITE_INSERT, pTab->zName, 0,
                       db->aDb[iDb].zDbSName) ){
    goto insert_cleanup;
  }
  withoutRowid = !HasRowid(pTab);

  /* Figure out if we have any triggers and if the table being
  ** inserted into is a view
  */
#ifndef SQLITE_OMIT_TRIGGER
  pTrigger = sqlite3TriggersExist(pParse, pTab, TK_INSERT, 0, &tmask);
  isView = pTab->pSelect!=0;
#else
# define pTrigger 0
# define tmask 0
# define isView 0
#endif
#ifdef SQLITE_OMIT_VIEW
# undef isView
# define isView 0
#endif
  assert( (pTrigger && tmask) || (pTrigger==0 && tmask==0) );

  /* If pTab is really a view, make sure it has been initialized.
  ** ViewGetColumnNames() is a no-op if pTab is not a view.
  */
  if( sqlite3ViewGetColumnNames(pParse, pTab) ){
    goto insert_cleanup;
  }

  /* Cannot insert into a read-only table.
  */
  if( sqlite3IsReadOnly(pParse, pTab, tmask) ){
    goto insert_cleanup;
  }

  /* Allocate a VDBE
  */
  v = sqlite3GetVdbe(pParse);
  if( v==0 ) goto insert_cleanup;
  if( pParse->nested==0 ) sqlite3VdbeCountChanges(v);
  sqlite3BeginWriteOperation(pParse, pSelect || pTrigger, iDb);

#ifndef SQLITE_OMIT_XFER_OPT
  /* If the statement is of the form
  **
  **       INSERT INTO <table1> SELECT * FROM <table2>;
  **
  ** Then special optimizations can be applied that make the transfer
  ** very fast and which reduce fragmentation of indices.
  **
  ** This is the 2nd template.
  */
  if( pColumn==0 && xferOptimization(pParse, pTab, pSelect, onError, iDb) ){
    assert( !pTrigger );
    assert( pList==0 );
    goto insert_end;
  }
#endif /* SQLITE_OMIT_XFER_OPT */

  /* If this is an AUTOINCREMENT table, look up the sequence number in the
  ** sqlite_sequence table and store it in memory cell regAutoinc.
  */
  regAutoinc = autoIncBegin(pParse, iDb, pTab);

  /* Allocate registers for holding the rowid of the new row,
  ** the content of the new row, and the assembled row record.
  */
  regRowid = regIns = pParse->nMem+1;
  pParse->nMem += pTab->nCol + 1;
  if( IsVirtual(pTab) ){
    regRowid++;
    pParse->nMem++;
  }
  regData = regRowid+1;

  /* If the INSERT statement included an IDLIST term, then make sure
  ** all elements of the IDLIST really are columns of the table and 
  ** remember the column indices.
  **
  ** If the table has an INTEGER PRIMARY KEY column and that column
  ** is named in the IDLIST, then record in the ipkColumn variable
  ** the index into IDLIST of the primary key column.  ipkColumn is
  ** the index of the primary key as it appears in IDLIST, not as
  ** is appears in the original table.  (The index of the INTEGER
  ** PRIMARY KEY in the original table is pTab->iPKey.)
  */
  bIdListInOrder = (pTab->tabFlags & TF_OOOHidden)==0;
  if( pColumn ){
    for(i=0; i<pColumn->nId; i++){
      pColumn->a[i].idx = -1;
    }
    for(i=0; i<pColumn->nId; i++){
      for(j=0; j<pTab->nCol; j++){
        if( sqlite3StrICmp(pColumn->a[i].zName, pTab->aCol[j].zName)==0 ){
          pColumn->a[i].idx = j;
          if( i!=j ) bIdListInOrder = 0;
          if( j==pTab->iPKey ){
            ipkColumn = i;  assert( !withoutRowid );
          }
          break;
        }
      }
      if( j>=pTab->nCol ){
        if( sqlite3IsRowid(pColumn->a[i].zName) && !withoutRowid ){
          ipkColumn = i;
          bIdListInOrder = 0;
        }else{
          sqlite3ErrorMsg(pParse, "table %S has no column named %s",
              pTabList, 0, pColumn->a[i].zName);
          pParse->checkSchema = 1;
          goto insert_cleanup;
        }
      }
    }
  }

  /* Figure out how many columns of data are supplied.  If the data
  ** is coming from a SELECT statement, then generate a co-routine that
  ** produces a single row of the SELECT on each invocation.  The
  ** co-routine is the common header to the 3rd and 4th templates.
  */
  if( pSelect ){
    /* Data is coming from a SELECT or from a multi-row VALUES clause.
    ** Generate a co-routine to run the SELECT. */
    int regYield;       /* Register holding co-routine entry-point */
    int addrTop;        /* Top of the co-routine */
    int rc;             /* Result code */

    regYield = ++pParse->nMem;
    addrTop = sqlite3VdbeCurrentAddr(v) + 1;
    sqlite3VdbeAddOp3(v, OP_InitCoroutine, regYield, 0, addrTop);
    sqlite3SelectDestInit(&dest, SRT_Coroutine, regYield);
    dest.iSdst = bIdListInOrder ? regData : 0;
    dest.nSdst = pTab->nCol;
    rc = sqlite3Select(pParse, pSelect, &dest);
    regFromSelect = dest.iSdst;
    if( rc || db->mallocFailed || pParse->nErr ) goto insert_cleanup;
    sqlite3VdbeEndCoroutine(v, regYield);
    sqlite3VdbeJumpHere(v, addrTop - 1);                       /* label B: */
    assert( pSelect->pEList );
    nColumn = pSelect->pEList->nExpr;

    /* Set useTempTable to TRUE if the result of the SELECT statement
    ** should be written into a temporary table (template 4).  Set to
    ** FALSE if each output row of the SELECT can be written directly into
    ** the destination table (template 3).
    **
    ** A temp table must be used if the table being updated is also one
    ** of the tables being read by the SELECT statement.  Also use a 
    ** temp table in the case of row triggers.
    */
    if( pTrigger || readsTable(pParse, iDb, pTab) ){
      useTempTable = 1;
    }

    if( useTempTable ){
      /* Invoke the coroutine to extract information from the SELECT
      ** and add it to a transient table srcTab.  The code generated
      ** here is from the 4th template:
      **
      **      B: open temp table
      **      L: yield X, goto M at EOF
      **         insert row from R..R+n into temp table
      **         goto L
      **      M: ...
      */
      int regRec;          /* Register to hold packed record */
      int regTempRowid;    /* Register to hold temp table ROWID */
      int addrL;           /* Label "L" */

      srcTab = pParse->nTab++;
      regRec = sqlite3GetTempReg(pParse);
      regTempRowid = sqlite3GetTempReg(pParse);
      sqlite3VdbeAddOp2(v, OP_OpenEphemeral, srcTab, nColumn);
      addrL = sqlite3VdbeAddOp1(v, OP_Yield, dest.iSDParm); VdbeCoverage(v);
      sqlite3VdbeAddOp3(v, OP_MakeRecord, regFromSelect, nColumn, regRec);
      sqlite3VdbeAddOp2(v, OP_NewRowid, srcTab, regTempRowid);
      sqlite3VdbeAddOp3(v, OP_Insert, srcTab, regRec, regTempRowid);
      sqlite3VdbeGoto(v, addrL);
      sqlite3VdbeJumpHere(v, addrL);
      sqlite3ReleaseTempReg(pParse, regRec);
      sqlite3ReleaseTempReg(pParse, regTempRowid);
    }
  }else{
    /* This is the case if the data for the INSERT is coming from a 
    ** single-row VALUES clause
    */
    NameContext sNC;
    memset(&sNC, 0, sizeof(sNC));
    sNC.pParse = pParse;
    srcTab = -1;
    assert( useTempTable==0 );
    if( pList ){
      nColumn = pList->nExpr;
      if( sqlite3ResolveExprListNames(&sNC, pList) ){
        goto insert_cleanup;
      }
    }else{
      nColumn = 0;
    }
  }

  /* If there is no IDLIST term but the table has an integer primary
  ** key, the set the ipkColumn variable to the integer primary key 
  ** column index in the original table definition.
  */
  if( pColumn==0 && nColumn>0 ){
    ipkColumn = pTab->iPKey;
  }

  /* Make sure the number of columns in the source data matches the number
  ** of columns to be inserted into the table.
  */
  for(i=0; i<pTab->nCol; i++){
    nHidden += (IsHiddenColumn(&pTab->aCol[i]) ? 1 : 0);
  }
  if( pColumn==0 && nColumn && nColumn!=(pTab->nCol-nHidden) ){
    sqlite3ErrorMsg(pParse, 
       "table %S has %d columns but %d values were supplied",
       pTabList, 0, pTab->nCol-nHidden, nColumn);
    goto insert_cleanup;
  }
  if( pColumn!=0 && nColumn!=pColumn->nId ){
    sqlite3ErrorMsg(pParse, "%d values for %d columns", nColumn, pColumn->nId);
    goto insert_cleanup;
  }
    
  /* Initialize the count of rows to be inserted
  */
  if( (db->flags & SQLITE_CountRows)!=0
   && !pParse->nested
   && !pParse->pTriggerTab
  ){
    regRowCount = ++pParse->nMem;
    sqlite3VdbeAddOp2(v, OP_Integer, 0, regRowCount);
  }

  /* If this is not a view, open the table and and all indices */
  if( !isView ){
    int nIdx;
    nIdx = sqlite3OpenTableAndIndices(pParse, pTab, OP_OpenWrite, 0, -1, 0,
                                      &iDataCur, &iIdxCur);
    aRegIdx = sqlite3DbMallocRawNN(db, sizeof(int)*(nIdx+2));
    if( aRegIdx==0 ){
      goto insert_cleanup;
    }
    for(i=0, pIdx=pTab->pIndex; i<nIdx; pIdx=pIdx->pNext, i++){
      assert( pIdx );
      aRegIdx[i] = ++pParse->nMem;
      pParse->nMem += pIdx->nColumn;
    }
    aRegIdx[i] = ++pParse->nMem;  /* Register to store the table record */
  }
#ifndef SQLITE_OMIT_UPSERT
  if( pUpsert ){
    if( IsVirtual(pTab) ){
      sqlite3ErrorMsg(pParse, "UPSERT not implemented for virtual table \"%s\"",
              pTab->zName);
      goto insert_cleanup;
    }
    if( sqlite3HasExplicitNulls(pParse, pUpsert->pUpsertTarget) ){
      goto insert_cleanup;
    }
    pTabList->a[0].iCursor = iDataCur;
    pUpsert->pUpsertSrc = pTabList;
    pUpsert->regData = regData;
    pUpsert->iDataCur = iDataCur;
    pUpsert->iIdxCur = iIdxCur;
    if( pUpsert->pUpsertTarget ){
      sqlite3UpsertAnalyzeTarget(pParse, pTabList, pUpsert);
    }
  }
#endif


  /* This is the top of the main insertion loop */
  if( useTempTable ){
    /* This block codes the top of loop only.  The complete loop is the
    ** following pseudocode (template 4):
    **
    **         rewind temp table, if empty goto D
    **      C: loop over rows of intermediate table
    **           transfer values form intermediate table into <table>
    **         end loop
    **      D: ...
    */
    addrInsTop = sqlite3VdbeAddOp1(v, OP_Rewind, srcTab); VdbeCoverage(v);
    addrCont = sqlite3VdbeCurrentAddr(v);
  }else if( pSelect ){
    /* This block codes the top of loop only.  The complete loop is the
    ** following pseudocode (template 3):
    **
    **      C: yield X, at EOF goto D
    **         insert the select result into <table> from R..R+n
    **         goto C
    **      D: ...
    */
    addrInsTop = addrCont = sqlite3VdbeAddOp1(v, OP_Yield, dest.iSDParm);
    VdbeCoverage(v);
  }

  /* Run the BEFORE and INSTEAD OF triggers, if there are any
  */
  endOfLoop = sqlite3VdbeMakeLabel(pParse);
  if( tmask & TRIGGER_BEFORE ){
    int regCols = sqlite3GetTempRange(pParse, pTab->nCol+1);

    /* build the NEW.* reference row.  Note that if there is an INTEGER
    ** PRIMARY KEY into which a NULL is being inserted, that NULL will be
    ** translated into a unique ID for the row.  But on a BEFORE trigger,
    ** we do not know what the unique ID will be (because the insert has
    ** not happened yet) so we substitute a rowid of -1
    */
    if( ipkColumn<0 ){
      sqlite3VdbeAddOp2(v, OP_Integer, -1, regCols);
    }else{
      int addr1;
      assert( !withoutRowid );
      if( useTempTable ){
        sqlite3VdbeAddOp3(v, OP_Column, srcTab, ipkColumn, regCols);
      }else{
        assert( pSelect==0 );  /* Otherwise useTempTable is true */
        sqlite3ExprCode(pParse, pList->a[ipkColumn].pExpr, regCols);
      }
      addr1 = sqlite3VdbeAddOp1(v, OP_NotNull, regCols); VdbeCoverage(v);
      sqlite3VdbeAddOp2(v, OP_Integer, -1, regCols);
      sqlite3VdbeJumpHere(v, addr1);
      sqlite3VdbeAddOp1(v, OP_MustBeInt, regCols); VdbeCoverage(v);
    }

    /* Cannot have triggers on a virtual table. If it were possible,
    ** this block would have to account for hidden column.
    */
    assert( !IsVirtual(pTab) );

    /* Create the new column data
    */
    for(i=j=0; i<pTab->nCol; i++){
      if( pColumn ){
        for(j=0; j<pColumn->nId; j++){
          if( pColumn->a[j].idx==i ) break;
        }
      }
      if( (!useTempTable && !pList) || (pColumn && j>=pColumn->nId)
            || (pColumn==0 && IsOrdinaryHiddenColumn(&pTab->aCol[i])) ){
        sqlite3ExprCode(pParse, pTab->aCol[i].pDflt, regCols+i+1);
      }else if( useTempTable ){
        sqlite3VdbeAddOp3(v, OP_Column, srcTab, j, regCols+i+1); 
      }else{
        assert( pSelect==0 ); /* Otherwise useTempTable is true */
        sqlite3ExprCodeAndCache(pParse, pList->a[j].pExpr, regCols+i+1);
      }
      if( pColumn==0 && !IsOrdinaryHiddenColumn(&pTab->aCol[i]) ) j++;
    }

    /* If this is an INSERT on a view with an INSTEAD OF INSERT trigger,
    ** do not attempt any conversions before assembling the record.
    ** If this is a real table, attempt conversions as required by the
    ** table column affinities.
    */
    if( !isView ){
      sqlite3TableAffinity(v, pTab, regCols+1);
    }

    /* Fire BEFORE or INSTEAD OF triggers */
    sqlite3CodeRowTrigger(pParse, pTrigger, TK_INSERT, 0, TRIGGER_BEFORE, 
        pTab, regCols-pTab->nCol-1, onError, endOfLoop);

    sqlite3ReleaseTempRange(pParse, regCols, pTab->nCol+1);
  }

  /* Compute the content of the next row to insert into a range of
  ** registers beginning at regIns.
  */
  if( !isView ){
    if( IsVirtual(pTab) ){
      /* The row that the VUpdate opcode will delete: none */
      sqlite3VdbeAddOp2(v, OP_Null, 0, regIns);
    }
    if( ipkColumn>=0 ){
      if( useTempTable ){
        sqlite3VdbeAddOp3(v, OP_Column, srcTab, ipkColumn, regRowid);
      }else if( pSelect ){
        sqlite3VdbeAddOp2(v, OP_Copy, regFromSelect+ipkColumn, regRowid);
      }else{
        Expr *pIpk = pList->a[ipkColumn].pExpr;
        if( pIpk->op==TK_NULL && !IsVirtual(pTab) ){
          sqlite3VdbeAddOp3(v, OP_NewRowid, iDataCur, regRowid, regAutoinc);
          appendFlag = 1;
        }else{
          sqlite3ExprCode(pParse, pList->a[ipkColumn].pExpr, regRowid);
        }
      }
      /* If the PRIMARY KEY expression is NULL, then use OP_NewRowid
      ** to generate a unique primary key value.
      */
      if( !appendFlag ){
        int addr1;
        if( !IsVirtual(pTab) ){
          addr1 = sqlite3VdbeAddOp1(v, OP_NotNull, regRowid); VdbeCoverage(v);
          sqlite3VdbeAddOp3(v, OP_NewRowid, iDataCur, regRowid, regAutoinc);
          sqlite3VdbeJumpHere(v, addr1);
        }else{
          addr1 = sqlite3VdbeCurrentAddr(v);
          sqlite3VdbeAddOp2(v, OP_IsNull, regRowid, addr1+2); VdbeCoverage(v);
        }
        sqlite3VdbeAddOp1(v, OP_MustBeInt, regRowid); VdbeCoverage(v);
      }
    }else if( IsVirtual(pTab) || withoutRowid ){
      sqlite3VdbeAddOp2(v, OP_Null, 0, regRowid);
    }else{
      sqlite3VdbeAddOp3(v, OP_NewRowid, iDataCur, regRowid, regAutoinc);
      appendFlag = 1;
    }
    autoIncStep(pParse, regAutoinc, regRowid);

    /* Compute data for all columns of the new entry, beginning
    ** with the first column.
    */
    nHidden = 0;
    for(i=0; i<pTab->nCol; i++){
      int iRegStore = regRowid+1+i;
      if( i==pTab->iPKey ){
        /* The value of the INTEGER PRIMARY KEY column is always a NULL.
        ** Whenever this column is read, the rowid will be substituted
        ** in its place.  Hence, fill this column with a NULL to avoid
        ** taking up data space with information that will never be used.
        ** As there may be shallow copies of this value, make it a soft-NULL */
        sqlite3VdbeAddOp1(v, OP_SoftNull, iRegStore);
        continue;
      }
      if( pColumn==0 ){
        if( IsHiddenColumn(&pTab->aCol[i]) ){
          j = -1;
          nHidden++;
        }else{
          j = i - nHidden;
        }
      }else{
        for(j=0; j<pColumn->nId; j++){
          if( pColumn->a[j].idx==i ) break;
        }
      }
      if( j<0 || nColumn==0 || (pColumn && j>=pColumn->nId) ){
        sqlite3ExprCodeFactorable(pParse, pTab->aCol[i].pDflt, iRegStore);
      }else if( useTempTable ){
        sqlite3VdbeAddOp3(v, OP_Column, srcTab, j, iRegStore); 
      }else if( pSelect ){
        if( regFromSelect!=regData ){
          sqlite3VdbeAddOp2(v, OP_SCopy, regFromSelect+j, iRegStore);
        }
      }else{
        sqlite3ExprCode(pParse, pList->a[j].pExpr, iRegStore);
      }
    }

    /* Generate code to check constraints and generate index keys and
    ** do the insertion.
    */
#ifndef SQLITE_OMIT_VIRTUALTABLE
    if( IsVirtual(pTab) ){
      const char *pVTab = (const char *)sqlite3GetVTable(db, pTab);
      sqlite3VtabMakeWritable(pParse, pTab);
      sqlite3VdbeAddOp4(v, OP_VUpdate, 1, pTab->nCol+2, regIns, pVTab, P4_VTAB);
      sqlite3VdbeChangeP5(v, onError==OE_Default ? OE_Abort : onError);
      sqlite3MayAbort(pParse);
    }else
#endif
    {
      int isReplace;    /* Set to true if constraints may cause a replace */
      int bUseSeek;     /* True to use OPFLAG_SEEKRESULT */
      sqlite3GenerateConstraintChecks(pParse, pTab, aRegIdx, iDataCur, iIdxCur,
          regIns, 0, ipkColumn>=0, onError, endOfLoop, &isReplace, 0, pUpsert
      );
      sqlite3FkCheck(pParse, pTab, 0, regIns, 0, 0);

      /* Set the OPFLAG_USESEEKRESULT flag if either (a) there are no REPLACE
      ** constraints or (b) there are no triggers and this table is not a
      ** parent table in a foreign key constraint. It is safe to set the
      ** flag in the second case as if any REPLACE constraint is hit, an
      ** OP_Delete or OP_IdxDelete instruction will be executed on each 
      ** cursor that is disturbed. And these instructions both clear the
      ** VdbeCursor.seekResult variable, disabling the OPFLAG_USESEEKRESULT
      ** functionality.  */
      bUseSeek = (isReplace==0 || !sqlite3VdbeHasSubProgram(v));
      sqlite3CompleteInsertion(pParse, pTab, iDataCur, iIdxCur,
          regIns, aRegIdx, 0, appendFlag, bUseSeek
      );
    }
  }

  /* Update the count of rows that are inserted
  */
  if( regRowCount ){
    sqlite3VdbeAddOp2(v, OP_AddImm, regRowCount, 1);
  }

  if( pTrigger ){
    /* Code AFTER triggers */
    sqlite3CodeRowTrigger(pParse, pTrigger, TK_INSERT, 0, TRIGGER_AFTER, 
        pTab, regData-2-pTab->nCol, onError, endOfLoop);
  }

  /* The bottom of the main insertion loop, if the data source
  ** is a SELECT statement.
  */
  sqlite3VdbeResolveLabel(v, endOfLoop);
  if( useTempTable ){
    sqlite3VdbeAddOp2(v, OP_Next, srcTab, addrCont); VdbeCoverage(v);
    sqlite3VdbeJumpHere(v, addrInsTop);
    sqlite3VdbeAddOp1(v, OP_Close, srcTab);
  }else if( pSelect ){
    sqlite3VdbeGoto(v, addrCont);
    sqlite3VdbeJumpHere(v, addrInsTop);
  }

insert_end:
  /* Update the sqlite_sequence table by storing the content of the
  ** maximum rowid counter values recorded while inserting into
  ** autoincrement tables.
  */
  if( pParse->nested==0 && pParse->pTriggerTab==0 ){
    sqlite3AutoincrementEnd(pParse);
  }

  /*
  ** Return the number of rows inserted. If this routine is 
  ** generating code because of a call to sqlite3NestedParse(), do not
  ** invoke the callback function.
  */
  if( regRowCount ){
    sqlite3VdbeAddOp2(v, OP_ResultRow, regRowCount, 1);
    sqlite3VdbeSetNumCols(v, 1);
    sqlite3VdbeSetColName(v, 0, COLNAME_NAME, "rows inserted", SQLITE_STATIC);
  }

insert_cleanup:
  sqlite3SrcListDelete(db, pTabList);
  sqlite3ExprListDelete(db, pList);
  sqlite3UpsertDelete(db, pUpsert);
  sqlite3SelectDelete(db, pSelect);
  sqlite3IdListDelete(db, pColumn);
  sqlite3DbFree(db, aRegIdx);
}

/* Make sure "isView" and other macros defined above are undefined. Otherwise
** they may interfere with compilation of other functions in this file
** (or in another file, if this file becomes part of the amalgamation).  */
#ifdef isView
 #undef isView
#endif
#ifdef pTrigger
 #undef pTrigger
#endif
#ifdef tmask
 #undef tmask
#endif

/*
** Meanings of bits in of pWalker->eCode for 
** sqlite3ExprReferencesUpdatedColumn()
*/
#define CKCNSTRNT_COLUMN   0x01    /* CHECK constraint uses a changing column */
#define CKCNSTRNT_ROWID    0x02    /* CHECK constraint references the ROWID */

/* This is the Walker callback from sqlite3ExprReferencesUpdatedColumn().
*  Set bit 0x01 of pWalker->eCode if pWalker->eCode to 0 and if this
** expression node references any of the
** columns that are being modifed by an UPDATE statement.
*/
static int checkConstraintExprNode(Walker *pWalker, Expr *pExpr){
  if( pExpr->op==TK_COLUMN ){
    assert( pExpr->iColumn>=0 || pExpr->iColumn==-1 );
    if( pExpr->iColumn>=0 ){
      if( pWalker->u.aiCol[pExpr->iColumn]>=0 ){
        pWalker->eCode |= CKCNSTRNT_COLUMN;
      }
    }else{
      pWalker->eCode |= CKCNSTRNT_ROWID;
    }
  }
  return WRC_Continue;
}

/*
** pExpr is a CHECK constraint on a row that is being UPDATE-ed.  The
** only columns that are modified by the UPDATE are those for which
** aiChng[i]>=0, and also the ROWID is modified if chngRowid is true.
**
** Return true if CHECK constraint pExpr uses any of the
** changing columns (or the rowid if it is changing).  In other words,
** return true if this CHECK constraint must be validated for
** the new row in the UPDATE statement.
**
** 2018-09-15: pExpr might also be an expression for an index-on-expressions.
** The operation of this routine is the same - return true if an only if
** the expression uses one or more of columns identified by the second and
** third arguments.
*/
int sqlite3ExprReferencesUpdatedColumn(
  Expr *pExpr,    /* The expression to be checked */
  int *aiChng,    /* aiChng[x]>=0 if column x changed by the UPDATE */
  int chngRowid   /* True if UPDATE changes the rowid */
){
  Walker w;
  memset(&w, 0, sizeof(w));
  w.eCode = 0;
  w.xExprCallback = checkConstraintExprNode;
  w.u.aiCol = aiChng;
  sqlite3WalkExpr(&w, pExpr);
  if( !chngRowid ){
    testcase( (w.eCode & CKCNSTRNT_ROWID)!=0 );
    w.eCode &= ~CKCNSTRNT_ROWID;
  }
  testcase( w.eCode==0 );
  testcase( w.eCode==CKCNSTRNT_COLUMN );
  testcase( w.eCode==CKCNSTRNT_ROWID );
  testcase( w.eCode==(CKCNSTRNT_ROWID|CKCNSTRNT_COLUMN) );
  return w.eCode!=0;
}

/*
** Generate code to do constraint checks prior to an INSERT or an UPDATE
** on table pTab.
**
** The regNewData parameter is the first register in a range that contains
** the data to be inserted or the data after the update.  There will be
** pTab->nCol+1 registers in this range.  The first register (the one
** that regNewData points to) will contain the new rowid, or NULL in the
** case of a WITHOUT ROWID table.  The second register in the range will
** contain the content of the first table column.  The third register will
** contain the content of the second table column.  And so forth.
**
** The regOldData parameter is similar to regNewData except that it contains
** the data prior to an UPDATE rather than afterwards.  regOldData is zero
** for an INSERT.  This routine can distinguish between UPDATE and INSERT by
** checking regOldData for zero.
**
** For an UPDATE, the pkChng boolean is true if the true primary key (the
** rowid for a normal table or the PRIMARY KEY for a WITHOUT ROWID table)
** might be modified by the UPDATE.  If pkChng is false, then the key of
** the iDataCur content table is guaranteed to be unchanged by the UPDATE.
**
** For an INSERT, the pkChng boolean indicates whether or not the rowid
** was explicitly specified as part of the INSERT statement.  If pkChng
** is zero, it means that the either rowid is computed automatically or
** that the table is a WITHOUT ROWID table and has no rowid.  On an INSERT,
** pkChng will only be true if the INSERT statement provides an integer
** value for either the rowid column or its INTEGER PRIMARY KEY alias.
**
** The code generated by this routine will store new index entries into
** registers identified by aRegIdx[].  No index entry is created for
** indices where aRegIdx[i]==0.  The order of indices in aRegIdx[] is
** the same as the order of indices on the linked list of indices
** at pTab->pIndex.
**
** (2019-05-07) The generated code also creates a new record for the
** main table, if pTab is a rowid table, and stores that record in the
** register identified by aRegIdx[nIdx] - in other words in the first
** entry of aRegIdx[] past the last index.  It is important that the
** record be generated during constraint checks to avoid affinity changes
** to the register content that occur after constraint checks but before
** the new record is inserted.
**
** The caller must have already opened writeable cursors on the main
** table and all applicable indices (that is to say, all indices for which
** aRegIdx[] is not zero).  iDataCur is the cursor for the main table when
** inserting or updating a rowid table, or the cursor for the PRIMARY KEY
** index when operating on a WITHOUT ROWID table.  iIdxCur is the cursor
** for the first index in the pTab->pIndex list.  Cursors for other indices
** are at iIdxCur+N for the N-th element of the pTab->pIndex list.
**
** This routine also generates code to check constraints.  NOT NULL,
** CHECK, and UNIQUE constraints are all checked.  If a constraint fails,
** then the appropriate action is performed.  There are five possible
** actions: ROLLBACK, ABORT, FAIL, REPLACE, and IGNORE.
**
**  Constraint type  Action       What Happens
**  ---------------  ----------   ----------------------------------------
**  any              ROLLBACK     The current transaction is rolled back and
**                                sqlite3_step() returns immediately with a
**                                return code of SQLITE_CONSTRAINT.
**
**  any              ABORT        Back out changes from the current command
**                                only (do not do a complete rollback) then
**                                cause sqlite3_step() to return immediately
**                                with SQLITE_CONSTRAINT.
**
**  any              FAIL         Sqlite3_step() returns immediately with a
**                                return code of SQLITE_CONSTRAINT.  The
**                                transaction is not rolled back and any
**                                changes to prior rows are retained.
**
**  any              IGNORE       The attempt in insert or update the current
**                                row is skipped, without throwing an error.
**                                Processing continues with the next row.
**                                (There is an immediate jump to ignoreDest.)
**
**  NOT NULL         REPLACE      The NULL value is replace by the default
**                                value for that column.  If the default value
**                                is NULL, the action is the same as ABORT.
**
**  UNIQUE           REPLACE      The other row that conflicts with the row
**                                being inserted is removed.
**
**  CHECK            REPLACE      Illegal.  The results in an exception.
**
** Which action to take is determined by the overrideError parameter.
** Or if overrideError==OE_Default, then the pParse->onError parameter
** is used.  Or if pParse->onError==OE_Default then the onError value
** for the constraint is used.
*/
void sqlite3GenerateConstraintChecks(
  Parse *pParse,       /* The parser context */
  Table *pTab,         /* The table being inserted or updated */
  int *aRegIdx,        /* Use register aRegIdx[i] for index i.  0 for unused */
  int iDataCur,        /* Canonical data cursor (main table or PK index) */
  int iIdxCur,         /* First index cursor */
  int regNewData,      /* First register in a range holding values to insert */
  int regOldData,      /* Previous content.  0 for INSERTs */
  u8 pkChng,           /* Non-zero if the rowid or PRIMARY KEY changed */
  u8 overrideError,    /* Override onError to this if not OE_Default */
  int ignoreDest,      /* Jump to this label on an OE_Ignore resolution */
  int *pbMayReplace,   /* OUT: Set to true if constraint may cause a replace */
  int *aiChng,         /* column i is unchanged if aiChng[i]<0 */
  Upsert *pUpsert      /* ON CONFLICT clauses, if any.  NULL otherwise */
){
  Vdbe *v;             /* VDBE under constrution */
  Index *pIdx;         /* Pointer to one of the indices */
  Index *pPk = 0;      /* The PRIMARY KEY index */
  sqlite3 *db;         /* Database connection */
  int i;               /* loop counter */
  int ix;              /* Index loop counter */
  int nCol;            /* Number of columns */
  int onError;         /* Conflict resolution strategy */
  int addr1;           /* Address of jump instruction */
  int seenReplace = 0; /* True if REPLACE is used to resolve INT PK conflict */
  int nPkField;        /* Number of fields in PRIMARY KEY. 1 for ROWID tables */
  Index *pUpIdx = 0;   /* Index to which to apply the upsert */
  u8 isUpdate;         /* True if this is an UPDATE operation */
  u8 bAffinityDone = 0;  /* True if the OP_Affinity operation has been run */
  int upsertBypass = 0;  /* Address of Goto to bypass upsert subroutine */
  int upsertJump = 0;    /* Address of Goto that jumps into upsert subroutine */
  int ipkTop = 0;        /* Top of the IPK uniqueness check */
  int ipkBottom = 0;     /* OP_Goto at the end of the IPK uniqueness check */
  /* Variables associated with retesting uniqueness constraints after
  ** replace triggers fire have run */
  int regTrigCnt;       /* Register used to count replace trigger invocations */
  int addrRecheck = 0;  /* Jump here to recheck all uniqueness constraints */
  int lblRecheckOk = 0; /* Each recheck jumps to this label if it passes */
  Trigger *pTrigger;    /* List of DELETE triggers on the table pTab */
  int nReplaceTrig = 0; /* Number of replace triggers coded */

  isUpdate = regOldData!=0;
  db = pParse->db;
  v = sqlite3GetVdbe(pParse);
  assert( v!=0 );
  assert( pTab->pSelect==0 );  /* This table is not a VIEW */
  nCol = pTab->nCol;
  
  /* pPk is the PRIMARY KEY index for WITHOUT ROWID tables and NULL for
  ** normal rowid tables.  nPkField is the number of key fields in the 
  ** pPk index or 1 for a rowid table.  In other words, nPkField is the
  ** number of fields in the true primary key of the table. */
  if( HasRowid(pTab) ){
    pPk = 0;
    nPkField = 1;
  }else{
    pPk = sqlite3PrimaryKeyIndex(pTab);
    nPkField = pPk->nKeyCol;
  }

  /* Record that this module has started */
  VdbeModuleComment((v, "BEGIN: GenCnstCks(%d,%d,%d,%d,%d)",
                     iDataCur, iIdxCur, regNewData, regOldData, pkChng));

  /* Test all NOT NULL constraints.
  */
  if( pTab->tabFlags & TF_HasNotNull ){
    for(i=0; i<nCol; i++){
      onError = pTab->aCol[i].notNull;
      if( onError==OE_None ) continue; /* No NOT NULL on this column */
      assert( pTab->tabFlags & TF_HasNotNull );
      if( i==pTab->iPKey ){
        continue;        /* ROWID is never NULL */
      }
      if( aiChng && aiChng[i]<0 ){
        /* Don't bother checking for NOT NULL on columns that do not change */
        continue;
      }
      if( overrideError!=OE_Default ){
        onError = overrideError;
      }else if( onError==OE_Default ){
        onError = OE_Abort;
      }
      if( onError==OE_Replace && pTab->aCol[i].pDflt==0 ){
        onError = OE_Abort;
      }
      assert( onError==OE_Rollback || onError==OE_Abort || onError==OE_Fail
          || onError==OE_Ignore || onError==OE_Replace );
      addr1 = 0;
      switch( onError ){
        case OE_Replace: {
          assert( onError==OE_Replace );
          addr1 = sqlite3VdbeMakeLabel(pParse);
          sqlite3VdbeAddOp2(v, OP_NotNull, regNewData+1+i, addr1);
            VdbeCoverage(v);
          sqlite3ExprCode(pParse, pTab->aCol[i].pDflt, regNewData+1+i);
          sqlite3VdbeAddOp2(v, OP_NotNull, regNewData+1+i, addr1);
            VdbeCoverage(v);
          onError = OE_Abort;
          /* Fall through into the OE_Abort case to generate code that runs
          ** if both the input and the default value are NULL */
        }
        case OE_Abort:
          sqlite3MayAbort(pParse);
          /* Fall through */
        case OE_Rollback:
        case OE_Fail: {
          char *zMsg = sqlite3MPrintf(db, "%s.%s", pTab->zName,
                                      pTab->aCol[i].zName);
          sqlite3VdbeAddOp3(v, OP_HaltIfNull, SQLITE_CONSTRAINT_NOTNULL,
                            onError, regNewData+1+i);
          sqlite3VdbeAppendP4(v, zMsg, P4_DYNAMIC);
          sqlite3VdbeChangeP5(v, P5_ConstraintNotNull);
          VdbeCoverage(v);
          if( addr1 ) sqlite3VdbeResolveLabel(v, addr1);
          break;
        }
        default: {
          assert( onError==OE_Ignore );
          sqlite3VdbeAddOp2(v, OP_IsNull, regNewData+1+i, ignoreDest);
          VdbeCoverage(v);
          break;
        }
      }
    }
  }
  
  /* Test all CHECK constraints
  */
#ifndef SQLITE_OMIT_CHECK
  if( pTab->pCheck && (db->flags & SQLITE_IgnoreChecks)==0 ){
    ExprList *pCheck = pTab->pCheck;
    pParse->iSelfTab = -(regNewData+1);
    onError = overrideError!=OE_Default ? overrideError : OE_Abort;
    for(i=0; i<pCheck->nExpr; i++){
      int allOk;
      Expr *pExpr = pCheck->a[i].pExpr;
      if( aiChng
       && !sqlite3ExprReferencesUpdatedColumn(pExpr, aiChng, pkChng)
      ){
        /* The check constraints do not reference any of the columns being
        ** updated so there is no point it verifying the check constraint */
        continue;
      }
      allOk = sqlite3VdbeMakeLabel(pParse);
      sqlite3VdbeVerifyAbortable(v, onError);
      sqlite3ExprIfTrue(pParse, pExpr, allOk, SQLITE_JUMPIFNULL);
      if( onError==OE_Ignore ){
        sqlite3VdbeGoto(v, ignoreDest);
      }else{
        char *zName = pCheck->a[i].zName;
        if( zName==0 ) zName = pTab->zName;
        if( onError==OE_Replace ) onError = OE_Abort; /* IMP: R-26383-51744 */
        sqlite3HaltConstraint(pParse, SQLITE_CONSTRAINT_CHECK,
                              onError, zName, P4_TRANSIENT,
                              P5_ConstraintCheck);
      }
      sqlite3VdbeResolveLabel(v, allOk);
    }
    pParse->iSelfTab = 0;
  }
#endif /* !defined(SQLITE_OMIT_CHECK) */

  /* UNIQUE and PRIMARY KEY constraints should be handled in the following
  ** order:
  **
  **   (1)  OE_Update
  **   (2)  OE_Abort, OE_Fail, OE_Rollback, OE_Ignore
  **   (3)  OE_Replace
  **
  ** OE_Fail and OE_Ignore must happen before any changes are made.
  ** OE_Update guarantees that only a single row will change, so it
  ** must happen before OE_Replace.  Technically, OE_Abort and OE_Rollback
  ** could happen in any order, but they are grouped up front for
  ** convenience.
  **
  ** 2018-08-14: Ticket https://www.sqlite.org/src/info/908f001483982c43
  ** The order of constraints used to have OE_Update as (2) and OE_Abort
  ** and so forth as (1). But apparently PostgreSQL checks the OE_Update
  ** constraint before any others, so it had to be moved.
  **
  ** Constraint checking code is generated in this order:
  **   (A)  The rowid constraint
  **   (B)  Unique index constraints that do not have OE_Replace as their
  **        default conflict resolution strategy
  **   (C)  Unique index that do use OE_Replace by default.
  **
  ** The ordering of (2) and (3) is accomplished by making sure the linked
  ** list of indexes attached to a table puts all OE_Replace indexes last
  ** in the list.  See sqlite3CreateIndex() for where that happens.
  */

  if( pUpsert ){
    if( pUpsert->pUpsertTarget==0 ){
      /* An ON CONFLICT DO NOTHING clause, without a constraint-target.
      ** Make all unique constraint resolution be OE_Ignore */
      assert( pUpsert->pUpsertSet==0 );
      overrideError = OE_Ignore;
      pUpsert = 0;
    }else if( (pUpIdx = pUpsert->pUpsertIdx)!=0 ){
      /* If the constraint-target uniqueness check must be run first.
      ** Jump to that uniqueness check now */
      upsertJump = sqlite3VdbeAddOp0(v, OP_Goto);
      VdbeComment((v, "UPSERT constraint goes first"));
    }
  }

  /* Determine if it is possible that triggers (either explicitly coded
  ** triggers or FK resolution actions) might run as a result of deletes
  ** that happen when OE_Replace conflict resolution occurs. (Call these
  ** "replace triggers".)  If any replace triggers run, we will need to
  ** recheck all of the uniqueness constraints after they have all run.
  ** But on the recheck, the resolution is OE_Abort instead of OE_Replace.
  **
  ** If replace triggers are a possibility, then
  **
  **   (1) Allocate register regTrigCnt and initialize it to zero.
  **       That register will count the number of replace triggers that
  **       fire.  Constraint recheck only occurs if the number is positive.
  **   (2) Initialize pTrigger to the list of all DELETE triggers on pTab.
  **   (3) Initialize addrRecheck and lblRecheckOk
  **
  ** The uniqueness rechecking code will create a series of tests to run
  ** in a second pass.  The addrRecheck and lblRecheckOk variables are
  ** used to link together these tests which are separated from each other
  ** in the generate bytecode.
  */
  if( (db->flags & (SQLITE_RecTriggers|SQLITE_ForeignKeys))==0 ){
    /* There are not DELETE triggers nor FK constraints.  No constraint
    ** rechecks are needed. */
    pTrigger = 0;
    regTrigCnt = 0;
  }else{
    if( db->flags&SQLITE_RecTriggers ){
      pTrigger = sqlite3TriggersExist(pParse, pTab, TK_DELETE, 0, 0);
      regTrigCnt = pTrigger!=0 || sqlite3FkRequired(pParse, pTab, 0, 0);
    }else{
      pTrigger = 0;
      regTrigCnt = sqlite3FkRequired(pParse, pTab, 0, 0);
    }
    if( regTrigCnt ){
      /* Replace triggers might exist.  Allocate the counter and
      ** initialize it to zero. */
      regTrigCnt = ++pParse->nMem;
      sqlite3VdbeAddOp2(v, OP_Integer, 0, regTrigCnt);
      VdbeComment((v, "trigger count"));
      lblRecheckOk = sqlite3VdbeMakeLabel(pParse);
      addrRecheck = lblRecheckOk;
    }
  }

  /* If rowid is changing, make sure the new rowid does not previously
  ** exist in the table.
  */
  if( pkChng && pPk==0 ){
    int addrRowidOk = sqlite3VdbeMakeLabel(pParse);

    /* Figure out what action to take in case of a rowid collision */
    onError = pTab->keyConf;
    if( overrideError!=OE_Default ){
      onError = overrideError;
    }else if( onError==OE_Default ){
      onError = OE_Abort;
    }

    /* figure out whether or not upsert applies in this case */
    if( pUpsert && pUpsert->pUpsertIdx==0 ){
      if( pUpsert->pUpsertSet==0 ){
        onError = OE_Ignore;  /* DO NOTHING is the same as INSERT OR IGNORE */
      }else{
        onError = OE_Update;  /* DO UPDATE */
      }
    }

    /* If the response to a rowid conflict is REPLACE but the response
    ** to some other UNIQUE constraint is FAIL or IGNORE, then we need
    ** to defer the running of the rowid conflict checking until after
    ** the UNIQUE constraints have run.
    */
    if( onError==OE_Replace      /* IPK rule is REPLACE */
     && onError!=overrideError   /* Rules for other contraints are different */
     && pTab->pIndex             /* There exist other constraints */
    ){
      ipkTop = sqlite3VdbeAddOp0(v, OP_Goto)+1;
      VdbeComment((v, "defer IPK REPLACE until last"));
    }

    if( isUpdate ){
      /* pkChng!=0 does not mean that the rowid has changed, only that
      ** it might have changed.  Skip the conflict logic below if the rowid
      ** is unchanged. */
      sqlite3VdbeAddOp3(v, OP_Eq, regNewData, addrRowidOk, regOldData);
      sqlite3VdbeChangeP5(v, SQLITE_NOTNULL);
      VdbeCoverage(v);
    }

    /* Check to see if the new rowid already exists in the table.  Skip
    ** the following conflict logic if it does not. */
    VdbeNoopComment((v, "uniqueness check for ROWID"));
    sqlite3VdbeVerifyAbortable(v, onError);
    sqlite3VdbeAddOp3(v, OP_NotExists, iDataCur, addrRowidOk, regNewData);
    VdbeCoverage(v);

    switch( onError ){
      default: {
        onError = OE_Abort;
        /* Fall thru into the next case */
      }
      case OE_Rollback:
      case OE_Abort:
      case OE_Fail: {
        testcase( onError==OE_Rollback );
        testcase( onError==OE_Abort );
        testcase( onError==OE_Fail );
        sqlite3RowidConstraint(pParse, onError, pTab);
        break;
      }
      case OE_Replace: {
        /* If there are DELETE triggers on this table and the
        ** recursive-triggers flag is set, call GenerateRowDelete() to
        ** remove the conflicting row from the table. This will fire
        ** the triggers and remove both the table and index b-tree entries.
        **
        ** Otherwise, if there are no triggers or the recursive-triggers
        ** flag is not set, but the table has one or more indexes, call 
        ** GenerateRowIndexDelete(). This removes the index b-tree entries 
        ** only. The table b-tree entry will be replaced by the new entry 
        ** when it is inserted.  
        **
        ** If either GenerateRowDelete() or GenerateRowIndexDelete() is called,
        ** also invoke MultiWrite() to indicate that this VDBE may require
        ** statement rollback (if the statement is aborted after the delete
        ** takes place). Earlier versions called sqlite3MultiWrite() regardless,
        ** but being more selective here allows statements like:
        **
        **   REPLACE INTO t(rowid) VALUES($newrowid)
        **
        ** to run without a statement journal if there are no indexes on the
        ** table.
        */
        if( regTrigCnt ){
          sqlite3MultiWrite(pParse);
          sqlite3GenerateRowDelete(pParse, pTab, pTrigger, iDataCur, iIdxCur,
                                   regNewData, 1, 0, OE_Replace, 1, -1);
          sqlite3VdbeAddOp2(v, OP_AddImm, regTrigCnt, 1); /* incr trigger cnt */
          nReplaceTrig++;
        }else{
#ifdef SQLITE_ENABLE_PREUPDATE_HOOK
          assert( HasRowid(pTab) );
          /* This OP_Delete opcode fires the pre-update-hook only. It does
          ** not modify the b-tree. It is more efficient to let the coming
          ** OP_Insert replace the existing entry than it is to delete the
          ** existing entry and then insert a new one. */
          sqlite3VdbeAddOp2(v, OP_Delete, iDataCur, OPFLAG_ISNOOP);
          sqlite3VdbeAppendP4(v, pTab, P4_TABLE);
#endif /* SQLITE_ENABLE_PREUPDATE_HOOK */
          if( pTab->pIndex ){
            sqlite3MultiWrite(pParse);
            sqlite3GenerateRowIndexDelete(pParse, pTab, iDataCur, iIdxCur,0,-1);
          }
        }
        seenReplace = 1;
        break;
      }
#ifndef SQLITE_OMIT_UPSERT
      case OE_Update: {
        sqlite3UpsertDoUpdate(pParse, pUpsert, pTab, 0, iDataCur);
        /* Fall through */
      }
#endif
      case OE_Ignore: {
        testcase( onError==OE_Ignore );
        sqlite3VdbeGoto(v, ignoreDest);
        break;
      }
    }
    sqlite3VdbeResolveLabel(v, addrRowidOk);
    if( ipkTop ){
      ipkBottom = sqlite3VdbeAddOp0(v, OP_Goto);
      sqlite3VdbeJumpHere(v, ipkTop-1);
    }
  }

  /* Test all UNIQUE constraints by creating entries for each UNIQUE
  ** index and making sure that duplicate entries do not already exist.
  ** Compute the revised record entries for indices as we go.
  **
  ** This loop also handles the case of the PRIMARY KEY index for a
  ** WITHOUT ROWID table.
  */
  for(ix=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, ix++){
    int regIdx;          /* Range of registers hold conent for pIdx */
    int regR;            /* Range of registers holding conflicting PK */
    int iThisCur;        /* Cursor for this UNIQUE index */
    int addrUniqueOk;    /* Jump here if the UNIQUE constraint is satisfied */
    int addrConflictCk;  /* First opcode in the conflict check logic */

    if( aRegIdx[ix]==0 ) continue;  /* Skip indices that do not change */
    if( pUpIdx==pIdx ){
      addrUniqueOk = upsertJump+1;
      upsertBypass = sqlite3VdbeGoto(v, 0);
      VdbeComment((v, "Skip upsert subroutine"));
      sqlite3VdbeJumpHere(v, upsertJump);
    }else{
      addrUniqueOk = sqlite3VdbeMakeLabel(pParse);
    }
    if( bAffinityDone==0 && (pUpIdx==0 || pUpIdx==pIdx) ){
      sqlite3TableAffinity(v, pTab, regNewData+1);
      bAffinityDone = 1;
    }
    VdbeNoopComment((v, "uniqueness check for %s", pIdx->zName));
    iThisCur = iIdxCur+ix;


    /* Skip partial indices for which the WHERE clause is not true */
    if( pIdx->pPartIdxWhere ){
      sqlite3VdbeAddOp2(v, OP_Null, 0, aRegIdx[ix]);
      pParse->iSelfTab = -(regNewData+1);
      sqlite3ExprIfFalseDup(pParse, pIdx->pPartIdxWhere, addrUniqueOk,
                            SQLITE_JUMPIFNULL);
      pParse->iSelfTab = 0;
    }

    /* Create a record for this index entry as it should appear after
    ** the insert or update.  Store that record in the aRegIdx[ix] register
    */
    regIdx = aRegIdx[ix]+1;
    for(i=0; i<pIdx->nColumn; i++){
      int iField = pIdx->aiColumn[i];
      int x;
      if( iField==XN_EXPR ){
        pParse->iSelfTab = -(regNewData+1);
        sqlite3ExprCodeCopy(pParse, pIdx->aColExpr->a[i].pExpr, regIdx+i);
        pParse->iSelfTab = 0;
        VdbeComment((v, "%s column %d", pIdx->zName, i));
      }else{
        if( iField==XN_ROWID || iField==pTab->iPKey ){
          x = regNewData;
        }else{
          x = iField + regNewData + 1;
        }
        sqlite3VdbeAddOp2(v, iField<0 ? OP_IntCopy : OP_SCopy, x, regIdx+i);
        VdbeComment((v, "%s", iField<0 ? "rowid" : pTab->aCol[iField].zName));
      }
    }
    sqlite3VdbeAddOp3(v, OP_MakeRecord, regIdx, pIdx->nColumn, aRegIdx[ix]);
    VdbeComment((v, "for %s", pIdx->zName));
#ifdef SQLITE_ENABLE_NULL_TRIM
    if( pIdx->idxType==SQLITE_IDXTYPE_PRIMARYKEY ){
      sqlite3SetMakeRecordP5(v, pIdx->pTable);
    }
#endif

    /* In an UPDATE operation, if this index is the PRIMARY KEY index 
    ** of a WITHOUT ROWID table and there has been no change the
    ** primary key, then no collision is possible.  The collision detection
    ** logic below can all be skipped. */
    if( isUpdate && pPk==pIdx && pkChng==0 ){
      sqlite3VdbeResolveLabel(v, addrUniqueOk);
      continue;
    }

    /* Find out what action to take in case there is a uniqueness conflict */
    onError = pIdx->onError;
    if( onError==OE_None ){ 
      sqlite3VdbeResolveLabel(v, addrUniqueOk);
      continue;  /* pIdx is not a UNIQUE index */
    }
    if( overrideError!=OE_Default ){
      onError = overrideError;
    }else if( onError==OE_Default ){
      onError = OE_Abort;
    }

    /* Figure out if the upsert clause applies to this index */
    if( pUpIdx==pIdx ){
      if( pUpsert->pUpsertSet==0 ){
        onError = OE_Ignore;  /* DO NOTHING is the same as INSERT OR IGNORE */
      }else{
        onError = OE_Update;  /* DO UPDATE */
      }
    }

    /* Collision detection may be omitted if all of the following are true:
    **   (1) The conflict resolution algorithm is REPLACE
    **   (2) The table is a WITHOUT ROWID table
    **   (3) There are no secondary indexes on the table
    **   (4) No delete triggers need to be fired if there is a conflict
    **   (5) No FK constraint counters need to be updated if a conflict occurs.
    **
    ** This is not possible for ENABLE_PREUPDATE_HOOK builds, as the row
    ** must be explicitly deleted in order to ensure any pre-update hook
    ** is invoked.  */ 
#ifndef SQLITE_ENABLE_PREUPDATE_HOOK
    if( (ix==0 && pIdx->pNext==0)                   /* Condition 3 */
     && pPk==pIdx                                   /* Condition 2 */
     && onError==OE_Replace                         /* Condition 1 */
     && ( 0==(db->flags&SQLITE_RecTriggers) ||      /* Condition 4 */
          0==sqlite3TriggersExist(pParse, pTab, TK_DELETE, 0, 0))
     && ( 0==(db->flags&SQLITE_ForeignKeys) ||      /* Condition 5 */
         (0==pTab->pFKey && 0==sqlite3FkReferences(pTab)))
    ){
      sqlite3VdbeResolveLabel(v, addrUniqueOk);
      continue;
    }
#endif /* ifndef SQLITE_ENABLE_PREUPDATE_HOOK */

    /* Check to see if the new index entry will be unique */
    sqlite3VdbeVerifyAbortable(v, onError);
    addrConflictCk = 
      sqlite3VdbeAddOp4Int(v, OP_NoConflict, iThisCur, addrUniqueOk,
                           regIdx, pIdx->nKeyCol); VdbeCoverage(v);

    /* Generate code to handle collisions */
    regR = (pIdx==pPk) ? regIdx : sqlite3GetTempRange(pParse, nPkField);
    if( isUpdate || onError==OE_Replace ){
      if( HasRowid(pTab) ){
        sqlite3VdbeAddOp2(v, OP_IdxRowid, iThisCur, regR);
        /* Conflict only if the rowid of the existing index entry
        ** is different from old-rowid */
        if( isUpdate ){
          sqlite3VdbeAddOp3(v, OP_Eq, regR, addrUniqueOk, regOldData);
          sqlite3VdbeChangeP5(v, SQLITE_NOTNULL);
          VdbeCoverage(v);
        }
      }else{
        int x;
        /* Extract the PRIMARY KEY from the end of the index entry and
        ** store it in registers regR..regR+nPk-1 */
        if( pIdx!=pPk ){
          for(i=0; i<pPk->nKeyCol; i++){
            assert( pPk->aiColumn[i]>=0 );
            x = sqlite3ColumnOfIndex(pIdx, pPk->aiColumn[i]);
            sqlite3VdbeAddOp3(v, OP_Column, iThisCur, x, regR+i);
            VdbeComment((v, "%s.%s", pTab->zName,
                         pTab->aCol[pPk->aiColumn[i]].zName));
          }
        }
        if( isUpdate ){
          /* If currently processing the PRIMARY KEY of a WITHOUT ROWID 
          ** table, only conflict if the new PRIMARY KEY values are actually
          ** different from the old.
          **
          ** For a UNIQUE index, only conflict if the PRIMARY KEY values
          ** of the matched index row are different from the original PRIMARY
          ** KEY values of this row before the update.  */
          int addrJump = sqlite3VdbeCurrentAddr(v)+pPk->nKeyCol;
          int op = OP_Ne;
          int regCmp = (IsPrimaryKeyIndex(pIdx) ? regIdx : regR);
  
          for(i=0; i<pPk->nKeyCol; i++){
            char *p4 = (char*)sqlite3LocateCollSeq(pParse, pPk->azColl[i]);
            x = pPk->aiColumn[i];
            assert( x>=0 );
            if( i==(pPk->nKeyCol-1) ){
              addrJump = addrUniqueOk;
              op = OP_Eq;
            }
            sqlite3VdbeAddOp4(v, op, 
                regOldData+1+x, addrJump, regCmp+i, p4, P4_COLLSEQ
            );
            sqlite3VdbeChangeP5(v, SQLITE_NOTNULL);
            VdbeCoverageIf(v, op==OP_Eq);
            VdbeCoverageIf(v, op==OP_Ne);
          }
        }
      }
    }

    /* Generate code that executes if the new index entry is not unique */
    assert( onError==OE_Rollback || onError==OE_Abort || onError==OE_Fail
        || onError==OE_Ignore || onError==OE_Replace || onError==OE_Update );
    switch( onError ){
      case OE_Rollback:
      case OE_Abort:
      case OE_Fail: {
        testcase( onError==OE_Rollback );
        testcase( onError==OE_Abort );
        testcase( onError==OE_Fail );
        sqlite3UniqueConstraint(pParse, onError, pIdx);
        break;
      }
#ifndef SQLITE_OMIT_UPSERT
      case OE_Update: {
        sqlite3UpsertDoUpdate(pParse, pUpsert, pTab, pIdx, iIdxCur+ix);
        /* Fall through */
      }
#endif
      case OE_Ignore: {
        testcase( onError==OE_Ignore );
        sqlite3VdbeGoto(v, ignoreDest);
        break;
      }
      default: {
        int nConflictCk;   /* Number of opcodes in conflict check logic */

        assert( onError==OE_Replace );
        nConflictCk = sqlite3VdbeCurrentAddr(v) - addrConflictCk;
        assert( nConflictCk>0 );
        testcase( nConflictCk>1 );
        if( regTrigCnt ){
          sqlite3MultiWrite(pParse);
          nReplaceTrig++;
        }
        sqlite3GenerateRowDelete(pParse, pTab, pTrigger, iDataCur, iIdxCur,
            regR, nPkField, 0, OE_Replace,
            (pIdx==pPk ? ONEPASS_SINGLE : ONEPASS_OFF), iThisCur);
        if( regTrigCnt ){
          int addrBypass;  /* Jump destination to bypass recheck logic */

          sqlite3VdbeAddOp2(v, OP_AddImm, regTrigCnt, 1); /* incr trigger cnt */
          addrBypass = sqlite3VdbeAddOp0(v, OP_Goto);  /* Bypass recheck */
          VdbeComment((v, "bypass recheck"));

          /* Here we insert code that will be invoked after all constraint
          ** checks have run, if and only if one or more replace triggers
          ** fired. */
          sqlite3VdbeResolveLabel(v, lblRecheckOk);
          lblRecheckOk = sqlite3VdbeMakeLabel(pParse);
          if( pIdx->pPartIdxWhere ){
            /* Bypass the recheck if this partial index is not defined
            ** for the current row */
            sqlite3VdbeAddOp2(v, OP_IsNull, regIdx-1, lblRecheckOk);
            VdbeCoverage(v);
          }
          /* Copy the constraint check code from above, except change
          ** the constraint-ok jump destination to be the address of
          ** the next retest block */
          while( nConflictCk>0 ){
            VdbeOp x;    /* Conflict check opcode to copy */
            /* The sqlite3VdbeAddOp4() call might reallocate the opcode array.
            ** Hence, make a complete copy of the opcode, rather than using
            ** a pointer to the opcode. */
            x = *sqlite3VdbeGetOp(v, addrConflictCk);
            if( x.opcode!=OP_IdxRowid ){
              int p2;      /* New P2 value for copied conflict check opcode */
              if( sqlite3OpcodeProperty[x.opcode]&OPFLG_JUMP ){
                p2 = lblRecheckOk;
              }else{
                p2 = x.p2;
              }
              sqlite3VdbeAddOp4(v, x.opcode, x.p1, p2, x.p3, x.p4.z, x.p4type);
              sqlite3VdbeChangeP5(v, x.p5);
              VdbeCoverageIf(v, p2!=x.p2);
            }
            nConflictCk--;
            addrConflictCk++;
          }
          /* If the retest fails, issue an abort */
          sqlite3UniqueConstraint(pParse, OE_Abort, pIdx);

          sqlite3VdbeJumpHere(v, addrBypass); /* Terminate the recheck bypass */
        }
        seenReplace = 1;
        break;
      }
    }
    if( pUpIdx==pIdx ){
      sqlite3VdbeGoto(v, upsertJump+1);
      sqlite3VdbeJumpHere(v, upsertBypass);
    }else{
      sqlite3VdbeResolveLabel(v, addrUniqueOk);
    }
    if( regR!=regIdx ) sqlite3ReleaseTempRange(pParse, regR, nPkField);
  }

  /* If the IPK constraint is a REPLACE, run it last */
  if( ipkTop ){
    sqlite3VdbeGoto(v, ipkTop);
    VdbeComment((v, "Do IPK REPLACE"));
    sqlite3VdbeJumpHere(v, ipkBottom);
  }

  /* Recheck all uniqueness constraints after replace triggers have run */
  testcase( regTrigCnt!=0 && nReplaceTrig==0 );
  assert( regTrigCnt!=0 || nReplaceTrig==0 );
  if( nReplaceTrig ){
    sqlite3VdbeAddOp2(v, OP_IfNot, regTrigCnt, lblRecheckOk);VdbeCoverage(v);
    if( !pPk ){
      if( isUpdate ){
        sqlite3VdbeAddOp3(v, OP_Eq, regNewData, addrRecheck, regOldData);
        sqlite3VdbeChangeP5(v, SQLITE_NOTNULL);
        VdbeCoverage(v);
      }
      sqlite3VdbeAddOp3(v, OP_NotExists, iDataCur, addrRecheck, regNewData);
      VdbeCoverage(v);
      sqlite3RowidConstraint(pParse, OE_Abort, pTab);
    }else{
      sqlite3VdbeGoto(v, addrRecheck);
    }
    sqlite3VdbeResolveLabel(v, lblRecheckOk);
  }

  /* Generate the table record */
  if( HasRowid(pTab) ){
    int regRec = aRegIdx[ix];
    sqlite3VdbeAddOp3(v, OP_MakeRecord, regNewData+1, pTab->nCol, regRec);
    sqlite3SetMakeRecordP5(v, pTab);
    if( !bAffinityDone ){
      sqlite3TableAffinity(v, pTab, 0);
    }
  }

  *pbMayReplace = seenReplace;
  VdbeModuleComment((v, "END: GenCnstCks(%d)", seenReplace));
}

#ifdef SQLITE_ENABLE_NULL_TRIM
/*
** Change the P5 operand on the last opcode (which should be an OP_MakeRecord)
** to be the number of columns in table pTab that must not be NULL-trimmed.
**
** Or if no columns of pTab may be NULL-trimmed, leave P5 at zero.
*/
void sqlite3SetMakeRecordP5(Vdbe *v, Table *pTab){
  u16 i;

  /* Records with omitted columns are only allowed for schema format
  ** version 2 and later (SQLite version 3.1.4, 2005-02-20). */
  if( pTab->pSchema->file_format<2 ) return;

  for(i=pTab->nCol-1; i>0; i--){
    if( pTab->aCol[i].pDflt!=0 ) break;
    if( pTab->aCol[i].colFlags & COLFLAG_PRIMKEY ) break;
  }
  sqlite3VdbeChangeP5(v, i+1);
}
#endif

/*
** This routine generates code to finish the INSERT or UPDATE operation
** that was started by a prior call to sqlite3GenerateConstraintChecks.
** A consecutive range of registers starting at regNewData contains the
** rowid and the content to be inserted.
**
** The arguments to this routine should be the same as the first six
** arguments to sqlite3GenerateConstraintChecks.
*/
void sqlite3CompleteInsertion(
  Parse *pParse,      /* The parser context */
  Table *pTab,        /* the table into which we are inserting */
  int iDataCur,       /* Cursor of the canonical data source */
  int iIdxCur,        /* First index cursor */
  int regNewData,     /* Range of content */
  int *aRegIdx,       /* Register used by each index.  0 for unused indices */
  int update_flags,   /* True for UPDATE, False for INSERT */
  int appendBias,     /* True if this is likely to be an append */
  int useSeekResult   /* True to set the USESEEKRESULT flag on OP_[Idx]Insert */
){
  Vdbe *v;            /* Prepared statements under construction */
  Index *pIdx;        /* An index being inserted or updated */
  u8 pik_flags;       /* flag values passed to the btree insert */
  int i;              /* Loop counter */

  assert( update_flags==0
       || update_flags==OPFLAG_ISUPDATE
       || update_flags==(OPFLAG_ISUPDATE|OPFLAG_SAVEPOSITION)
  );

  v = sqlite3GetVdbe(pParse);
  assert( v!=0 );
  assert( pTab->pSelect==0 );  /* This table is not a VIEW */
  for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){
    if( aRegIdx[i]==0 ) continue;
    if( pIdx->pPartIdxWhere ){
      sqlite3VdbeAddOp2(v, OP_IsNull, aRegIdx[i], sqlite3VdbeCurrentAddr(v)+2);
      VdbeCoverage(v);
    }
    pik_flags = (useSeekResult ? OPFLAG_USESEEKRESULT : 0);
    if( IsPrimaryKeyIndex(pIdx) && !HasRowid(pTab) ){
      assert( pParse->nested==0 );
      pik_flags |= OPFLAG_NCHANGE;
      pik_flags |= (update_flags & OPFLAG_SAVEPOSITION);
#ifdef SQLITE_ENABLE_PREUPDATE_HOOK
      if( update_flags==0 ){
        int r = sqlite3GetTempReg(pParse);
        sqlite3VdbeAddOp2(v, OP_Integer, 0, r);
        sqlite3VdbeAddOp4(v, OP_Insert, 
            iIdxCur+i, aRegIdx[i], r, (char*)pTab, P4_TABLE
        );
        sqlite3VdbeChangeP5(v, OPFLAG_ISNOOP);
        sqlite3ReleaseTempReg(pParse, r);
      }
#endif
    }
    sqlite3VdbeAddOp4Int(v, OP_IdxInsert, iIdxCur+i, aRegIdx[i],
                         aRegIdx[i]+1,
                         pIdx->uniqNotNull ? pIdx->nKeyCol: pIdx->nColumn);
    sqlite3VdbeChangeP5(v, pik_flags);
  }
  if( !HasRowid(pTab) ) return;
  if( pParse->nested ){
    pik_flags = 0;
  }else{
    pik_flags = OPFLAG_NCHANGE;
    pik_flags |= (update_flags?update_flags:OPFLAG_LASTROWID);
  }
  if( appendBias ){
    pik_flags |= OPFLAG_APPEND;
  }
  if( useSeekResult ){
    pik_flags |= OPFLAG_USESEEKRESULT;
  }
  sqlite3VdbeAddOp3(v, OP_Insert, iDataCur, aRegIdx[i], regNewData);
  if( !pParse->nested ){
    sqlite3VdbeAppendP4(v, pTab, P4_TABLE);
  }
  sqlite3VdbeChangeP5(v, pik_flags);
}

/*
** Allocate cursors for the pTab table and all its indices and generate
** code to open and initialized those cursors.
**
** The cursor for the object that contains the complete data (normally
** the table itself, but the PRIMARY KEY index in the case of a WITHOUT
** ROWID table) is returned in *piDataCur.  The first index cursor is
** returned in *piIdxCur.  The number of indices is returned.
**
** Use iBase as the first cursor (either the *piDataCur for rowid tables
** or the first index for WITHOUT ROWID tables) if it is non-negative.
** If iBase is negative, then allocate the next available cursor.
**
** For a rowid table, *piDataCur will be exactly one less than *piIdxCur.
** For a WITHOUT ROWID table, *piDataCur will be somewhere in the range
** of *piIdxCurs, depending on where the PRIMARY KEY index appears on the
** pTab->pIndex list.
**
** If pTab is a virtual table, then this routine is a no-op and the
** *piDataCur and *piIdxCur values are left uninitialized.
*/
int sqlite3OpenTableAndIndices(
  Parse *pParse,   /* Parsing context */
  Table *pTab,     /* Table to be opened */
  int op,          /* OP_OpenRead or OP_OpenWrite */
  u8 p5,           /* P5 value for OP_Open* opcodes (except on WITHOUT ROWID) */
  int iBase,       /* Use this for the table cursor, if there is one */
  u8 *aToOpen,     /* If not NULL: boolean for each table and index */
  int *piDataCur,  /* Write the database source cursor number here */
  int *piIdxCur    /* Write the first index cursor number here */
){
  int i;
  int iDb;
  int iDataCur;
  Index *pIdx;
  Vdbe *v;

  assert( op==OP_OpenRead || op==OP_OpenWrite );
  assert( op==OP_OpenWrite || p5==0 );
  if( IsVirtual(pTab) ){
    /* This routine is a no-op for virtual tables. Leave the output
    ** variables *piDataCur and *piIdxCur uninitialized so that valgrind
    ** can detect if they are used by mistake in the caller. */
    return 0;
  }
  iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
  v = sqlite3GetVdbe(pParse);
  assert( v!=0 );
  if( iBase<0 ) iBase = pParse->nTab;
  iDataCur = iBase++;
  if( piDataCur ) *piDataCur = iDataCur;
  if( HasRowid(pTab) && (aToOpen==0 || aToOpen[0]) ){
    sqlite3OpenTable(pParse, iDataCur, iDb, pTab, op);
  }else{
    sqlite3TableLock(pParse, iDb, pTab->tnum, op==OP_OpenWrite, pTab->zName);
  }
  if( piIdxCur ) *piIdxCur = iBase;
  for(i=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){
    int iIdxCur = iBase++;
    assert( pIdx->pSchema==pTab->pSchema );
    if( IsPrimaryKeyIndex(pIdx) && !HasRowid(pTab) ){
      if( piDataCur ) *piDataCur = iIdxCur;
      p5 = 0;
    }
    if( aToOpen==0 || aToOpen[i+1] ){
      sqlite3VdbeAddOp3(v, op, iIdxCur, pIdx->tnum, iDb);
      sqlite3VdbeSetP4KeyInfo(pParse, pIdx);
      sqlite3VdbeChangeP5(v, p5);
      VdbeComment((v, "%s", pIdx->zName));
    }
  }
  if( iBase>pParse->nTab ) pParse->nTab = iBase;
  return i;
}


#ifdef SQLITE_TEST
/*
** The following global variable is incremented whenever the
** transfer optimization is used.  This is used for testing
** purposes only - to make sure the transfer optimization really
** is happening when it is supposed to.
*/
int sqlite3_xferopt_count;
#endif /* SQLITE_TEST */


#ifndef SQLITE_OMIT_XFER_OPT
/*
** Check to see if index pSrc is compatible as a source of data
** for index pDest in an insert transfer optimization.  The rules
** for a compatible index:
**
**    *   The index is over the same set of columns
**    *   The same DESC and ASC markings occurs on all columns
**    *   The same onError processing (OE_Abort, OE_Ignore, etc)
**    *   The same collating sequence on each column
**    *   The index has the exact same WHERE clause
*/
static int xferCompatibleIndex(Index *pDest, Index *pSrc){
  int i;
  assert( pDest && pSrc );
  assert( pDest->pTable!=pSrc->pTable );
  if( pDest->nKeyCol!=pSrc->nKeyCol ){
    return 0;   /* Different number of columns */
  }
  if( pDest->onError!=pSrc->onError ){
    return 0;   /* Different conflict resolution strategies */
  }
  for(i=0; i<pSrc->nKeyCol; i++){
    if( pSrc->aiColumn[i]!=pDest->aiColumn[i] ){
      return 0;   /* Different columns indexed */
    }
    if( pSrc->aiColumn[i]==XN_EXPR ){
      assert( pSrc->aColExpr!=0 && pDest->aColExpr!=0 );
      if( sqlite3ExprCompare(0, pSrc->aColExpr->a[i].pExpr,
                             pDest->aColExpr->a[i].pExpr, -1)!=0 ){
        return 0;   /* Different expressions in the index */
      }
    }
    if( pSrc->aSortOrder[i]!=pDest->aSortOrder[i] ){
      return 0;   /* Different sort orders */
    }
    if( sqlite3_stricmp(pSrc->azColl[i],pDest->azColl[i])!=0 ){
      return 0;   /* Different collating sequences */
    }
  }
  if( sqlite3ExprCompare(0, pSrc->pPartIdxWhere, pDest->pPartIdxWhere, -1) ){
    return 0;     /* Different WHERE clauses */
  }

  /* If no test above fails then the indices must be compatible */
  return 1;
}

/*
** Attempt the transfer optimization on INSERTs of the form
**
**     INSERT INTO tab1 SELECT * FROM tab2;
**
** The xfer optimization transfers raw records from tab2 over to tab1.  
** Columns are not decoded and reassembled, which greatly improves
** performance.  Raw index records are transferred in the same way.
**
** The xfer optimization is only attempted if tab1 and tab2 are compatible.
** There are lots of rules for determining compatibility - see comments
** embedded in the code for details.
**
** This routine returns TRUE if the optimization is guaranteed to be used.
** Sometimes the xfer optimization will only work if the destination table
** is empty - a factor that can only be determined at run-time.  In that
** case, this routine generates code for the xfer optimization but also
** does a test to see if the destination table is empty and jumps over the
** xfer optimization code if the test fails.  In that case, this routine
** returns FALSE so that the caller will know to go ahead and generate
** an unoptimized transfer.  This routine also returns FALSE if there
** is no chance that the xfer optimization can be applied.
**
** This optimization is particularly useful at making VACUUM run faster.
*/
static int xferOptimization(
  Parse *pParse,        /* Parser context */
  Table *pDest,         /* The table we are inserting into */
  Select *pSelect,      /* A SELECT statement to use as the data source */
  int onError,          /* How to handle constraint errors */
  int iDbDest           /* The database of pDest */
){
  sqlite3 *db = pParse->db;
  ExprList *pEList;                /* The result set of the SELECT */
  Table *pSrc;                     /* The table in the FROM clause of SELECT */
  Index *pSrcIdx, *pDestIdx;       /* Source and destination indices */
  struct SrcList_item *pItem;      /* An element of pSelect->pSrc */
  int i;                           /* Loop counter */
  int iDbSrc;                      /* The database of pSrc */
  int iSrc, iDest;                 /* Cursors from source and destination */
  int addr1, addr2;                /* Loop addresses */
  int emptyDestTest = 0;           /* Address of test for empty pDest */
  int emptySrcTest = 0;            /* Address of test for empty pSrc */
  Vdbe *v;                         /* The VDBE we are building */
  int regAutoinc;                  /* Memory register used by AUTOINC */
  int destHasUniqueIdx = 0;        /* True if pDest has a UNIQUE index */
  int regData, regRowid;           /* Registers holding data and rowid */

  if( pSelect==0 ){
    return 0;   /* Must be of the form  INSERT INTO ... SELECT ... */
  }
  if( pParse->pWith || pSelect->pWith ){
    /* Do not attempt to process this query if there are an WITH clauses
    ** attached to it. Proceeding may generate a false "no such table: xxx"
    ** error if pSelect reads from a CTE named "xxx".  */
    return 0;
  }
  if( sqlite3TriggerList(pParse, pDest) ){
    return 0;   /* tab1 must not have triggers */
  }
#ifndef SQLITE_OMIT_VIRTUALTABLE
  if( IsVirtual(pDest) ){
    return 0;   /* tab1 must not be a virtual table */
  }
#endif
  if( onError==OE_Default ){
    if( pDest->iPKey>=0 ) onError = pDest->keyConf;
    if( onError==OE_Default ) onError = OE_Abort;
  }
  assert(pSelect->pSrc);   /* allocated even if there is no FROM clause */
  if( pSelect->pSrc->nSrc!=1 ){
    return 0;   /* FROM clause must have exactly one term */
  }
  if( pSelect->pSrc->a[0].pSelect ){
    return 0;   /* FROM clause cannot contain a subquery */
  }
  if( pSelect->pWhere ){
    return 0;   /* SELECT may not have a WHERE clause */
  }
  if( pSelect->pOrderBy ){
    return 0;   /* SELECT may not have an ORDER BY clause */
  }
  /* Do not need to test for a HAVING clause.  If HAVING is present but
  ** there is no ORDER BY, we will get an error. */
  if( pSelect->pGroupBy ){
    return 0;   /* SELECT may not have a GROUP BY clause */
  }
  if( pSelect->pLimit ){
    return 0;   /* SELECT may not have a LIMIT clause */
  }
  if( pSelect->pPrior ){
    return 0;   /* SELECT may not be a compound query */
  }
  if( pSelect->selFlags & SF_Distinct ){
    return 0;   /* SELECT may not be DISTINCT */
  }
  pEList = pSelect->pEList;
  assert( pEList!=0 );
  if( pEList->nExpr!=1 ){
    return 0;   /* The result set must have exactly one column */
  }
  assert( pEList->a[0].pExpr );
  if( pEList->a[0].pExpr->op!=TK_ASTERISK ){
    return 0;   /* The result set must be the special operator "*" */
  }

  /* At this point we have established that the statement is of the
  ** correct syntactic form to participate in this optimization.  Now
  ** we have to check the semantics.
  */
  pItem = pSelect->pSrc->a;
  pSrc = sqlite3LocateTableItem(pParse, 0, pItem);
  if( pSrc==0 ){
    return 0;   /* FROM clause does not contain a real table */
  }
  if( pSrc->tnum==pDest->tnum && pSrc->pSchema==pDest->pSchema ){
    testcase( pSrc!=pDest ); /* Possible due to bad sqlite_master.rootpage */
    return 0;   /* tab1 and tab2 may not be the same table */
  }
  if( HasRowid(pDest)!=HasRowid(pSrc) ){
    return 0;   /* source and destination must both be WITHOUT ROWID or not */
  }
#ifndef SQLITE_OMIT_VIRTUALTABLE
  if( IsVirtual(pSrc) ){
    return 0;   /* tab2 must not be a virtual table */
  }
#endif
  if( pSrc->pSelect ){
    return 0;   /* tab2 may not be a view */
  }
  if( pDest->nCol!=pSrc->nCol ){
    return 0;   /* Number of columns must be the same in tab1 and tab2 */
  }
  if( pDest->iPKey!=pSrc->iPKey ){
    return 0;   /* Both tables must have the same INTEGER PRIMARY KEY */
  }
  for(i=0; i<pDest->nCol; i++){
    Column *pDestCol = &pDest->aCol[i];
    Column *pSrcCol = &pSrc->aCol[i];
#ifdef SQLITE_ENABLE_HIDDEN_COLUMNS
    if( (db->mDbFlags & DBFLAG_Vacuum)==0 
     && (pDestCol->colFlags | pSrcCol->colFlags) & COLFLAG_HIDDEN 
    ){
      return 0;    /* Neither table may have __hidden__ columns */
    }
#endif
    if( pDestCol->affinity!=pSrcCol->affinity ){
      return 0;    /* Affinity must be the same on all columns */
    }
    if( sqlite3_stricmp(pDestCol->zColl, pSrcCol->zColl)!=0 ){
      return 0;    /* Collating sequence must be the same on all columns */
    }
    if( pDestCol->notNull && !pSrcCol->notNull ){
      return 0;    /* tab2 must be NOT NULL if tab1 is */
    }
    /* Default values for second and subsequent columns need to match. */
    if( i>0 ){
      assert( pDestCol->pDflt==0 || pDestCol->pDflt->op==TK_SPAN );
      assert( pSrcCol->pDflt==0 || pSrcCol->pDflt->op==TK_SPAN );
      if( (pDestCol->pDflt==0)!=(pSrcCol->pDflt==0) 
       || (pDestCol->pDflt && strcmp(pDestCol->pDflt->u.zToken,
                                       pSrcCol->pDflt->u.zToken)!=0)
      ){
        return 0;    /* Default values must be the same for all columns */
      }
    }
  }
  for(pDestIdx=pDest->pIndex; pDestIdx; pDestIdx=pDestIdx->pNext){
    if( IsUniqueIndex(pDestIdx) ){
      destHasUniqueIdx = 1;
    }
    for(pSrcIdx=pSrc->pIndex; pSrcIdx; pSrcIdx=pSrcIdx->pNext){
      if( xferCompatibleIndex(pDestIdx, pSrcIdx) ) break;
    }
    if( pSrcIdx==0 ){
      return 0;    /* pDestIdx has no corresponding index in pSrc */
    }
    if( pSrcIdx->tnum==pDestIdx->tnum && pSrc->pSchema==pDest->pSchema
         && sqlite3FaultSim(411)==SQLITE_OK ){
      /* The sqlite3FaultSim() call allows this corruption test to be
      ** bypassed during testing, in order to exercise other corruption tests
      ** further downstream. */
      return 0;   /* Corrupt schema - two indexes on the same btree */
    }
  }
#ifndef SQLITE_OMIT_CHECK
  if( pDest->pCheck && sqlite3ExprListCompare(pSrc->pCheck,pDest->pCheck,-1) ){
    return 0;   /* Tables have different CHECK constraints.  Ticket #2252 */
  }
#endif
#ifndef SQLITE_OMIT_FOREIGN_KEY
  /* Disallow the transfer optimization if the destination table constains
  ** any foreign key constraints.  This is more restrictive than necessary.
  ** But the main beneficiary of the transfer optimization is the VACUUM 
  ** command, and the VACUUM command disables foreign key constraints.  So
  ** the extra complication to make this rule less restrictive is probably
  ** not worth the effort.  Ticket [6284df89debdfa61db8073e062908af0c9b6118e]
  */
  if( (db->flags & SQLITE_ForeignKeys)!=0 && pDest->pFKey!=0 ){
    return 0;
  }
#endif
  if( (db->flags & SQLITE_CountRows)!=0 ){
    return 0;  /* xfer opt does not play well with PRAGMA count_changes */
  }

  /* If we get this far, it means that the xfer optimization is at
  ** least a possibility, though it might only work if the destination
  ** table (tab1) is initially empty.
  */
#ifdef SQLITE_TEST
  sqlite3_xferopt_count++;
#endif
  iDbSrc = sqlite3SchemaToIndex(db, pSrc->pSchema);
  v = sqlite3GetVdbe(pParse);
  sqlite3CodeVerifySchema(pParse, iDbSrc);
  iSrc = pParse->nTab++;
  iDest = pParse->nTab++;
  regAutoinc = autoIncBegin(pParse, iDbDest, pDest);
  regData = sqlite3GetTempReg(pParse);
  regRowid = sqlite3GetTempReg(pParse);
  sqlite3OpenTable(pParse, iDest, iDbDest, pDest, OP_OpenWrite);
  assert( HasRowid(pDest) || destHasUniqueIdx );
  if( (db->mDbFlags & DBFLAG_Vacuum)==0 && (
      (pDest->iPKey<0 && pDest->pIndex!=0)          /* (1) */
   || destHasUniqueIdx                              /* (2) */
   || (onError!=OE_Abort && onError!=OE_Rollback)   /* (3) */
  )){
    /* In some circumstances, we are able to run the xfer optimization
    ** only if the destination table is initially empty. Unless the
    ** DBFLAG_Vacuum flag is set, this block generates code to make
    ** that determination. If DBFLAG_Vacuum is set, then the destination
    ** table is always empty.
    **
    ** Conditions under which the destination must be empty:
    **
    ** (1) There is no INTEGER PRIMARY KEY but there are indices.
    **     (If the destination is not initially empty, the rowid fields
    **     of index entries might need to change.)
    **
    ** (2) The destination has a unique index.  (The xfer optimization 
    **     is unable to test uniqueness.)
    **
    ** (3) onError is something other than OE_Abort and OE_Rollback.
    */
    addr1 = sqlite3VdbeAddOp2(v, OP_Rewind, iDest, 0); VdbeCoverage(v);
    emptyDestTest = sqlite3VdbeAddOp0(v, OP_Goto);
    sqlite3VdbeJumpHere(v, addr1);
  }
  if( HasRowid(pSrc) ){
    u8 insFlags;
    sqlite3OpenTable(pParse, iSrc, iDbSrc, pSrc, OP_OpenRead);
    emptySrcTest = sqlite3VdbeAddOp2(v, OP_Rewind, iSrc, 0); VdbeCoverage(v);
    if( pDest->iPKey>=0 ){
      addr1 = sqlite3VdbeAddOp2(v, OP_Rowid, iSrc, regRowid);
      sqlite3VdbeVerifyAbortable(v, onError);
      addr2 = sqlite3VdbeAddOp3(v, OP_NotExists, iDest, 0, regRowid);
      VdbeCoverage(v);
      sqlite3RowidConstraint(pParse, onError, pDest);
      sqlite3VdbeJumpHere(v, addr2);
      autoIncStep(pParse, regAutoinc, regRowid);
    }else if( pDest->pIndex==0 && !(db->mDbFlags & DBFLAG_VacuumInto) ){
      addr1 = sqlite3VdbeAddOp2(v, OP_NewRowid, iDest, regRowid);
    }else{
      addr1 = sqlite3VdbeAddOp2(v, OP_Rowid, iSrc, regRowid);
      assert( (pDest->tabFlags & TF_Autoincrement)==0 );
    }
    sqlite3VdbeAddOp3(v, OP_RowData, iSrc, regData, 1);
    if( db->mDbFlags & DBFLAG_Vacuum ){
      sqlite3VdbeAddOp1(v, OP_SeekEnd, iDest);
      insFlags = OPFLAG_NCHANGE|OPFLAG_LASTROWID|
                           OPFLAG_APPEND|OPFLAG_USESEEKRESULT;
    }else{
      insFlags = OPFLAG_NCHANGE|OPFLAG_LASTROWID|OPFLAG_APPEND;
    }
    sqlite3VdbeAddOp4(v, OP_Insert, iDest, regData, regRowid,
                      (char*)pDest, P4_TABLE);
    sqlite3VdbeChangeP5(v, insFlags);
    sqlite3VdbeAddOp2(v, OP_Next, iSrc, addr1); VdbeCoverage(v);
    sqlite3VdbeAddOp2(v, OP_Close, iSrc, 0);
    sqlite3VdbeAddOp2(v, OP_Close, iDest, 0);
  }else{
    sqlite3TableLock(pParse, iDbDest, pDest->tnum, 1, pDest->zName);
    sqlite3TableLock(pParse, iDbSrc, pSrc->tnum, 0, pSrc->zName);
  }
  for(pDestIdx=pDest->pIndex; pDestIdx; pDestIdx=pDestIdx->pNext){
    u8 idxInsFlags = 0;
    for(pSrcIdx=pSrc->pIndex; ALWAYS(pSrcIdx); pSrcIdx=pSrcIdx->pNext){
      if( xferCompatibleIndex(pDestIdx, pSrcIdx) ) break;
    }
    assert( pSrcIdx );
    sqlite3VdbeAddOp3(v, OP_OpenRead, iSrc, pSrcIdx->tnum, iDbSrc);
    sqlite3VdbeSetP4KeyInfo(pParse, pSrcIdx);
    VdbeComment((v, "%s", pSrcIdx->zName));
    sqlite3VdbeAddOp3(v, OP_OpenWrite, iDest, pDestIdx->tnum, iDbDest);
    sqlite3VdbeSetP4KeyInfo(pParse, pDestIdx);
    sqlite3VdbeChangeP5(v, OPFLAG_BULKCSR);
    VdbeComment((v, "%s", pDestIdx->zName));
    addr1 = sqlite3VdbeAddOp2(v, OP_Rewind, iSrc, 0); VdbeCoverage(v);
    sqlite3VdbeAddOp3(v, OP_RowData, iSrc, regData, 1);
    if( db->mDbFlags & DBFLAG_Vacuum ){
      /* This INSERT command is part of a VACUUM operation, which guarantees
      ** that the destination table is empty. If all indexed columns use
      ** collation sequence BINARY, then it can also be assumed that the
      ** index will be populated by inserting keys in strictly sorted 
      ** order. In this case, instead of seeking within the b-tree as part
      ** of every OP_IdxInsert opcode, an OP_SeekEnd is added before the
      ** OP_IdxInsert to seek to the point within the b-tree where each key 
      ** should be inserted. This is faster.
      **
      ** If any of the indexed columns use a collation sequence other than
      ** BINARY, this optimization is disabled. This is because the user 
      ** might change the definition of a collation sequence and then run
      ** a VACUUM command. In that case keys may not be written in strictly
      ** sorted order.  */
      for(i=0; i<pSrcIdx->nColumn; i++){
        const char *zColl = pSrcIdx->azColl[i];
        if( sqlite3_stricmp(sqlite3StrBINARY, zColl) ) break;
      }
      if( i==pSrcIdx->nColumn ){
        idxInsFlags = OPFLAG_USESEEKRESULT;
        sqlite3VdbeAddOp1(v, OP_SeekEnd, iDest);
      }
    }
    if( !HasRowid(pSrc) && pDestIdx->idxType==SQLITE_IDXTYPE_PRIMARYKEY ){
      idxInsFlags |= OPFLAG_NCHANGE;
    }
    sqlite3VdbeAddOp2(v, OP_IdxInsert, iDest, regData);
    sqlite3VdbeChangeP5(v, idxInsFlags|OPFLAG_APPEND);
    sqlite3VdbeAddOp2(v, OP_Next, iSrc, addr1+1); VdbeCoverage(v);
    sqlite3VdbeJumpHere(v, addr1);
    sqlite3VdbeAddOp2(v, OP_Close, iSrc, 0);
    sqlite3VdbeAddOp2(v, OP_Close, iDest, 0);
  }
  if( emptySrcTest ) sqlite3VdbeJumpHere(v, emptySrcTest);
  sqlite3ReleaseTempReg(pParse, regRowid);
  sqlite3ReleaseTempReg(pParse, regData);
  if( emptyDestTest ){
    sqlite3AutoincrementEnd(pParse);
    sqlite3VdbeAddOp2(v, OP_Halt, SQLITE_OK, 0);
    sqlite3VdbeJumpHere(v, emptyDestTest);
    sqlite3VdbeAddOp2(v, OP_Close, iDest, 0);
    return 0;
  }else{
    return 1;
  }
}
#endif /* SQLITE_OMIT_XFER_OPT */