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Commit2617551

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Teach deparsing of CASE expressions to cope with the simplified forms
that simplify_boolean_equality() may leave behind. This is only relevantif the user writes something a bit silly, like CASE x=y WHEN TRUE THEN.Per example from Michael Fuhr; may or may not explain bug #2106.
1 parent69525fc commit2617551

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1 file changed

+32
-7
lines changed

1 file changed

+32
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lines changed

‎src/backend/utils/adt/ruleutils.c

Lines changed: 32 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -3,7 +3,7 @@
33
*back to source text
44
*
55
* IDENTIFICATION
6-
* $PostgreSQL: pgsql/src/backend/utils/adt/ruleutils.c,v 1.209 2005/11/22 18:17:23 momjian Exp $
6+
* $PostgreSQL: pgsql/src/backend/utils/adt/ruleutils.c,v 1.210 2005/12/10 19:21:03 tgl Exp $
77
*
88
* This software is copyrighted by Jan Wieck - Hamburg.
99
*
@@ -3389,22 +3389,47 @@ get_rule_expr(Node *node, deparse_context *context,
33893389
foreach(temp,caseexpr->args)
33903390
{
33913391
CaseWhen*when= (CaseWhen*)lfirst(temp);
3392+
Node*w= (Node*)when->expr;
33923393

33933394
if (!PRETTY_INDENT(context))
33943395
appendStringInfoChar(buf,' ');
33953396
appendContextKeyword(context,"WHEN ",
33963397
0,0,0);
33973398
if (caseexpr->arg)
33983399
{
3399-
/* Show only the RHS of "CaseTestExpr = RHS" */
3400-
Node*rhs;
3400+
/*
3401+
* The parser should have produced WHEN clauses of
3402+
* the form "CaseTestExpr = RHS"; we want to show
3403+
* just the RHS. If the user wrote something silly
3404+
* like "CASE boolexpr WHEN TRUE THEN ...", then
3405+
* the optimizer's simplify_boolean_equality() may
3406+
* have reduced this to just "CaseTestExpr" or
3407+
* "NOT CaseTestExpr", for which we have to show
3408+
* "TRUE" or "FALSE".
3409+
*/
3410+
if (IsA(w,OpExpr))
3411+
{
3412+
Node*rhs;
34013413

3402-
Assert(IsA(when->expr,OpExpr));
3403-
rhs= (Node*)lsecond(((OpExpr*)when->expr)->args);
3404-
get_rule_expr(rhs,context, false);
3414+
Assert(IsA(linitial(((OpExpr*)w)->args),
3415+
CaseTestExpr));
3416+
rhs= (Node*)lsecond(((OpExpr*)w)->args);
3417+
get_rule_expr(rhs,context, false);
3418+
}
3419+
elseif (IsA(w,CaseTestExpr))
3420+
appendStringInfo(buf,"TRUE");
3421+
elseif (not_clause(w))
3422+
{
3423+
Assert(IsA(get_notclausearg((Expr*)w),
3424+
CaseTestExpr));
3425+
appendStringInfo(buf,"FALSE");
3426+
}
3427+
else
3428+
elog(ERROR,"unexpected CASE WHEN clause: %d",
3429+
(int)nodeTag(w));
34053430
}
34063431
else
3407-
get_rule_expr((Node*)when->expr,context, false);
3432+
get_rule_expr(w,context, false);
34083433
appendStringInfo(buf," THEN ");
34093434
get_rule_expr((Node*)when->result,context, true);
34103435
}

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