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Change the LEFT JOIN strength reduction optimization so that assumes that

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virtual table constraints can be true even if terms within the constraint
are NULL.  This works around dodgy virtual table implementations.

FossilOrigin-Name: cbb977fe1908431f3aad8e67668588b119e7d491724f2042af436f509a4f6623
This commit is contained in:
drh
2018-04-03 14:04:48 +00:00
parent 18e2b8af1c
commit 9881155d54
3 changed files with 28 additions and 10 deletions
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21
src/expr.c
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@@ -5037,6 +5037,27 @@ static int impliesNotNullRow(Walker *pWalker, Expr *pExpr){
return WRC_Abort;
}
return WRC_Prune;
/* Virtual tables are allowed to use constraints like x=NULL. So
** a term of the form x=y does not prove that y is not null if x
** is the column of a virtual table */
case TK_EQ:
case TK_NE:
case TK_LT:
case TK_LE:
case TK_GT:
case TK_GE:
testcase( pExpr->op==TK_EQ );
testcase( pExpr->op==TK_NE );
testcase( pExpr->op==TK_LT );
testcase( pExpr->op==TK_LE );
testcase( pExpr->op==TK_GT );
testcase( pExpr->op==TK_GE );
if( (pExpr->pLeft->op==TK_COLUMN && IsVirtual(pExpr->pLeft->pTab))
|| (pExpr->pRight->op==TK_COLUMN && IsVirtual(pExpr->pRight->pTab))
){
return WRC_Prune;
}
default:
return WRC_Continue;
}