Changes to reduce the heap space consumed by triggers, views and tables in the in-memory representation of the schema. Also to reduce the space used by prepared statements slightly. (CVS 6305)
FossilOrigin-Name: d9f6ffbc5ea090ba0daac571fc9a6c68b9c864e4
diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index 9d400fe..440771f 100644
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -11,7 +11,7 @@
*************************************************************************
** Internal interface definitions for SQLite.
**
-** @(#) $Id: sqliteInt.h,v 1.833 2009/02/05 16:53:43 drh Exp $
+** @(#) $Id: sqliteInt.h,v 1.834 2009/02/19 14:39:25 danielk1977 Exp $
*/
#ifndef _SQLITEINT_H_
#define _SQLITEINT_H_
@@ -1363,19 +1363,27 @@
** Each node of an expression in the parse tree is an instance
** of this structure.
**
-** Expr.op is the opcode. The integer parser token codes are reused
-** as opcodes here. For example, the parser defines TK_GE to be an integer
-** code representing the ">=" operator. This same integer code is reused
+** Expr.op is the opcode. The integer parser token codes are reused
+** as opcodes here. For example, the parser defines TK_GE to be an integer
+** code representing the ">=" operator. This same integer code is reused
** to represent the greater-than-or-equal-to operator in the expression
** tree.
**
-** Expr.pRight and Expr.pLeft are subexpressions. Expr.pList is a list
-** of argument if the expression is a function.
+** If the expression is an SQL literal (TK_INTEGER, TK_FLOAT, TK_BLOB,
+** or TK_STRING), then Expr.token contains the text of the SQL literal. If
+** the expression is a variable (TK_VARIABLE), then Expr.token contains the
+** variable name. Finally, if the expression is an SQL function (TK_FUNCTION),
+** then Expr.token contains the name of the function.
**
-** Expr.token is the operator token for this node. For some expressions
-** that have subexpressions, Expr.token can be the complete text that gave
-** rise to the Expr. In the latter case, the token is marked as being
-** a compound token.
+** Expr.pRight and Expr.pLeft are the left and right subexpressions of a
+** binary operator. Either or both may be NULL.
+**
+** Expr.x.pList is a list of arguments if the expression is an SQL function,
+** a CASE expression or an IN expression of the form "<lhs> IN (<y>, <z>...)".
+** Expr.x.pSelect is used if the expression is a sub-select or an expression of
+** the form "<lhs> IN (SELECT ...)". If the EP_xIsSelect bit is set in the
+** Expr.flags mask, then Expr.x.pSelect is valid. Otherwise, Expr.x.pList is
+** valid.
**
** An expression of the form ID or ID.ID refers to a column in a table.
** For such expressions, Expr.op is set to TK_COLUMN and Expr.iTable is
@@ -1385,10 +1393,9 @@
** value is also stored in the Expr.iAgg column in the aggregate so that
** it can be accessed after all aggregates are computed.
**
-** If the expression is a function, the Expr.iTable is an integer code
-** representing which function. If the expression is an unbound variable
-** marker (a question mark character '?' in the original SQL) then the
-** Expr.iTable holds the index number for that variable.
+** If the expression is an unbound variable marker (a question mark
+** character '?' in the original SQL) then the Expr.iTable holds the index
+** number for that variable.
**
** If the expression is a subquery then Expr.iColumn holds an integer
** register number containing the result of the subquery. If the
@@ -1396,32 +1403,62 @@
** gives a different answer at different times during statement processing
** then iTable is the address of a subroutine that computes the subquery.
**
-** The Expr.pSelect field points to a SELECT statement. The SELECT might
-** be the right operand of an IN operator. Or, if a scalar SELECT appears
-** in an expression the opcode is TK_SELECT and Expr.pSelect is the only
-** operand.
-**
** If the Expr is of type OP_Column, and the table it is selecting from
** is a disk table or the "old.*" pseudo-table, then pTab points to the
** corresponding table definition.
+**
+** ALLOCATION NOTES:
+**
+** Expr structures may be stored as part of the in-memory database schema,
+** for example as part of trigger, view or table definitions. In this case,
+** the amount of memory consumed by complex expressions may be significant.
+** For this reason, less than sizeof(Expr) bytes may be allocated for some
+** Expr structs stored as part of the in-memory database schema.
+**
+** If the EP_Reduced flag is set in Expr.flags, then only EXPR_REDUCEDSIZE
+** bytes of space are allocated for the expression structure. This is enough
+** space to store all fields up to and including the "Token span;" field.
+**
+** If the EP_TokenOnly flag is set in Expr.flags, then only EXPR_TOKENONLYSIZE
+** bytes of space are allocated for the expression structure. This is enough
+** space to store all fields up to and including the "Token token;" field.
*/
struct Expr {
u8 op; /* Operation performed by this node */
char affinity; /* The affinity of the column or 0 if not a column */
u16 flags; /* Various flags. See below */
- CollSeq *pColl; /* The collation type of the column or 0 */
- Expr *pLeft, *pRight; /* Left and right subnodes */
- ExprList *pList; /* A list of expressions used as function arguments
- ** or in "<expr> IN (<expr-list)" */
Token token; /* An operand token */
+
+ /* If the EP_TokenOnly flag is set in the Expr.flags mask, then no
+ ** space is allocated for the fields below this point. An attempt to
+ ** access them will result in a segfault or malfunction.
+ *********************************************************************/
+
Token span; /* Complete text of the expression */
+
+ /* If the EP_SpanOnly flag is set in the Expr.flags mask, then no
+ ** space is allocated for the fields below this point. An attempt to
+ ** access them will result in a segfault or malfunction.
+ *********************************************************************/
+
+ Expr *pLeft; /* Left subnode */
+ Expr *pRight; /* Right subnode */
+ union {
+ ExprList *pList; /* Function arguments or in "<expr> IN (<expr-list)" */
+ Select *pSelect; /* Used for sub-selects and "<expr> IN (<select>)" */
+ } x;
+ CollSeq *pColl; /* The collation type of the column or 0 */
+
+ /* If the EP_Reduced flag is set in the Expr.flags mask, then no
+ ** space is allocated for the fields below this point. An attempt to
+ ** access them will result in a segfault or malfunction.
+ *********************************************************************/
+
int iTable, iColumn; /* When op==TK_COLUMN, then this expr node means the
** iColumn-th field of the iTable-th table. */
AggInfo *pAggInfo; /* Used by TK_AGG_COLUMN and TK_AGG_FUNCTION */
int iAgg; /* Which entry in pAggInfo->aCol[] or ->aFunc[] */
int iRightJoinTable; /* If EP_FromJoin, the right table of the join */
- Select *pSelect; /* When the expression is a sub-select. Also the
- ** right side of "<expr> IN (<select>)" */
Table *pTab; /* Table for TK_COLUMN expressions. */
#if SQLITE_MAX_EXPR_DEPTH>0
int nHeight; /* Height of the tree headed by this node */
@@ -1443,6 +1480,12 @@
#define EP_AnyAff 0x0200 /* Can take a cached column of any affinity */
#define EP_FixedDest 0x0400 /* Result needed in a specific register */
#define EP_IntValue 0x0800 /* Integer value contained in iTable */
+#define EP_xIsSelect 0x1000 /* x.pSelect is valid (otherwise x.pList is) */
+
+#define EP_Reduced 0x2000 /* Expr struct is EXPR_REDUCEDSIZE bytes only */
+#define EP_TokenOnly 0x4000 /* Expr struct is EXPR_TOKENONLYSIZE bytes only */
+#define EP_SpanOnly 0x8000 /* Expr struct is EXPR_SPANONLYSIZE bytes only */
+
/*
** These macros can be used to test, set, or clear bits in the
** Expr.flags field.
@@ -1453,6 +1496,23 @@
#define ExprClearProperty(E,P) (E)->flags&=~(P)
/*
+** Macros to determine the number of bytes required by a normal Expr
+** struct, an Expr struct with the EP_Reduced flag set in Expr.flags
+** and an Expr struct with the EP_TokenOnly flag set.
+*/
+#define EXPR_FULLSIZE sizeof(Expr)
+#define EXPR_REDUCEDSIZE ((int)(&((Expr*)(0))->iTable))
+#define EXPR_TOKENONLYSIZE ((int)(&((Expr*)(0))->span))
+#define EXPR_SPANONLYSIZE ((int)(&((Expr*)(0))->pLeft))
+
+/*
+** Flags passed to the sqlite3ExprDup() function. See the header comment
+** above sqlite3ExprDup() for details.
+*/
+#define EXPRDUP_REDUCE 0x0001
+#define EXPRDUP_SPAN 0x0002
+
+/*
** A list of expressions. Each expression may optionally have a
** name. An expr/name combination can be used in several ways, such
** as the list of "expr AS ID" fields following a "SELECT" or in the
@@ -2379,12 +2439,12 @@
void sqlite3CompleteInsertion(Parse*, Table*, int, int, int*, int, int, int);
int sqlite3OpenTableAndIndices(Parse*, Table*, int, int);
void sqlite3BeginWriteOperation(Parse*, int, int);
-Expr *sqlite3ExprDup(sqlite3*,Expr*);
+Expr *sqlite3ExprDup(sqlite3*,Expr*,int);
void sqlite3TokenCopy(sqlite3*,Token*, Token*);
-ExprList *sqlite3ExprListDup(sqlite3*,ExprList*);
-SrcList *sqlite3SrcListDup(sqlite3*,SrcList*);
+ExprList *sqlite3ExprListDup(sqlite3*,ExprList*,int);
+SrcList *sqlite3SrcListDup(sqlite3*,SrcList*,int);
IdList *sqlite3IdListDup(sqlite3*,IdList*);
-Select *sqlite3SelectDup(sqlite3*,Select*);
+Select *sqlite3SelectDup(sqlite3*,Select*,int);
void sqlite3FuncDefInsert(FuncDefHash*, FuncDef*);
FuncDef *sqlite3FindFunction(sqlite3*,const char*,int,int,u8,int);
void sqlite3RegisterBuiltinFunctions(sqlite3*);