Initial implementation of the unlikely() SQL function used as a hint to
the query planner.
FossilOrigin-Name: 036fc37a034093a4c6fc190633bd41c2b7230d77
diff --git a/src/expr.c b/src/expr.c
index 6587ee1..ece0293 100644
--- a/src/expr.c
+++ b/src/expr.c
@@ -89,8 +89,16 @@
** an expression.
*/
Expr *sqlite3ExprSkipCollate(Expr *pExpr){
- while( pExpr && (pExpr->op==TK_COLLATE || pExpr->op==TK_AS) ){
- pExpr = pExpr->pLeft;
+ while( pExpr ){
+ if( pExpr->op==TK_COLLATE || pExpr->op==TK_AS ){
+ pExpr = pExpr->pLeft;
+ }else if( ExprHasAnyProperty(pExpr, EP_Hint) ){
+ assert( !ExprHasProperty(pExpr, EP_xIsSelect) );
+ assert( pExpr->x.pList->nExpr>0 );
+ pExpr = pExpr->x.pList->a[0].pExpr;
+ }else{
+ break;
+ }
}
return pExpr;
}
@@ -2649,6 +2657,14 @@
break;
}
+ /* The UNLIKELY() function is a no-op. The result is the value
+ ** of the first argument.
+ */
+ if( pDef->funcFlags & SQLITE_FUNC_UNLIKELY ){
+ assert( nFarg>=1 );
+ sqlite3ExprCode(pParse, pFarg->a[0].pExpr, target);
+ break;
+ }
if( pFarg ){
r1 = sqlite3GetTempRange(pParse, nFarg);