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Teach deparsing of CASE expressions to cope with the simplified forms

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that simplify_boolean_equality() may leave behind.  This is only relevant
if 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.
This commit is contained in:
Tom Lane 2005-12-10 19:21:03 +00:00
parent 69525fc0ef
commit 2617551431
1 changed files with 32 additions and 7 deletions
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39
src/backend/utils/adt/ruleutils.c
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@ -3,7 +3,7 @@
* back to source text
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/adt/ruleutils.c,v 1.209 2005/11/22 18:17:23 momjian Exp $
* $PostgreSQL: pgsql/src/backend/utils/adt/ruleutils.c,v 1.210 2005/12/10 19:21:03 tgl Exp $
*
* This software is copyrighted by Jan Wieck - Hamburg.
*
@ -3389,6 +3389,7 @@ get_rule_expr(Node *node, deparse_context *context,
foreach(temp, caseexpr->args)
{
CaseWhen *when = (CaseWhen *) lfirst(temp);
Node *w = (Node *) when->expr;
if (!PRETTY_INDENT(context))
appendStringInfoChar(buf, ' ');
@ -3396,15 +3397,39 @@ get_rule_expr(Node *node, deparse_context *context,
0, 0, 0);
if (caseexpr->arg)
{
/* Show only the RHS of "CaseTestExpr = RHS" */
Node *rhs;
/*
* The parser should have produced WHEN clauses of
* the form "CaseTestExpr = RHS"; we want to show
* just the RHS. If the user wrote something silly
* like "CASE boolexpr WHEN TRUE THEN ...", then
* the optimizer's simplify_boolean_equality() may
* have reduced this to just "CaseTestExpr" or
* "NOT CaseTestExpr", for which we have to show
* "TRUE" or "FALSE".
*/
if (IsA(w, OpExpr))
{
Node *rhs;
Assert(IsA(when->expr, OpExpr));
rhs = (Node *) lsecond(((OpExpr *) when->expr)->args);
get_rule_expr(rhs, context, false);
Assert(IsA(linitial(((OpExpr *) w)->args),
CaseTestExpr));
rhs = (Node *) lsecond(((OpExpr *) w)->args);
get_rule_expr(rhs, context, false);
}
else if (IsA(w, CaseTestExpr))
appendStringInfo(buf, "TRUE");
else if (not_clause(w))
{
Assert(IsA(get_notclausearg((Expr *) w),
CaseTestExpr));
appendStringInfo(buf, "FALSE");
}
else
elog(ERROR, "unexpected CASE WHEN clause: %d",
(int) nodeTag(w));
}
else
get_rule_expr((Node *) when->expr, context, false);
get_rule_expr(w, context, false);
appendStringInfo(buf, " THEN ");
get_rule_expr((Node *) when->result, context, true);
}