mirror of https://github.com/postgres/postgres
Don't let transform_null_equals=on affect CASE foo WHEN NULL ... constructs.
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.
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@ -587,12 +587,15 @@ transformAExprOp(ParseState *pstate, A_Expr *a)
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/*
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* Special-case "foo = NULL" and "NULL = foo" for compatibility with
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* standards-broken products (like Microsoft's). Turn these into IS NULL
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* exprs.
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* exprs. (If either side is a CaseTestExpr, then the expression was
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* generated internally from a CASE-WHEN expression, and
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* transform_null_equals does not apply.)
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*/
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if (Transform_null_equals &&
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list_length(a->name) == 1 &&
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strcmp(strVal(linitial(a->name)), "=") == 0 &&
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(exprIsNullConstant(lexpr) || exprIsNullConstant(rexpr)))
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(exprIsNullConstant(lexpr) || exprIsNullConstant(rexpr)) &&
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(!IsA(lexpr, CaseTestExpr) && !IsA(rexpr, CaseTestExpr)))
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{
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NullTest *n = makeNode(NullTest);
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