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Don't let transform_null_equals=on affect CASE foo WHEN NULL ... constructs.

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transform_null_equals is only supposed to affect "foo = NULL" expressions
given directly by the user, not the internal "foo = NULL" expression
generated from CASE-WHEN.

This fixes bug #6242, reported by Sergey. Backpatch to all supported
branches.
This commit is contained in:
Heikki Linnakangas 2011-10-08 11:17:40 +03:00
parent 041dceb259
commit 1ef60dab70
1 changed files with 5 additions and 2 deletions
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7
src/backend/parser/parse_expr.c
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@ -836,12 +836,15 @@ transformAExprOp(ParseState *pstate, A_Expr *a)
/*
* Special-case "foo = NULL" and "NULL = foo" for compatibility with
* standards-broken products (like Microsoft's). Turn these into IS NULL
* exprs.
* exprs. (If either side is a CaseTestExpr, then the expression was
* generated internally from a CASE-WHEN expression, and
* transform_null_equals does not apply.)
*/
if (Transform_null_equals &&
list_length(a->name) == 1 &&
strcmp(strVal(linitial(a->name)), "=") == 0 &&
(exprIsNullConstant(lexpr) || exprIsNullConstant(rexpr)))
(exprIsNullConstant(lexpr) || exprIsNullConstant(rexpr)) &&
(!IsA(lexpr, CaseTestExpr) && !IsA(rexpr, CaseTestExpr)))
{
NullTest *n = makeNode(NullTest);