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When displaying a Var that is a reference to a column of an unnamed join,

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try to display it as a reference to the underlying column instead.  This
is a legitimate substitution (it wouldn't be for a named join) and it
fixes some cases where the display would otherwise be ambiguous.  Per
example from Sim Zacks.
This commit is contained in:
Tom Lane
2004-10-27 18:09:41 +00:00
parent 3fe704209a
commit b2b0673e4b
2 changed files with 27 additions and 4 deletions
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25
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 1.183 2004/10/17 21:17:27 tgl Exp $
* $PostgreSQL: pgsql/src/backend/utils/adt/ruleutils.c,v 1.184 2004/10/27 18:09:38 tgl Exp $
*
* This software is copyrighted by Jan Wieck - Hamburg.
*
@ -2558,6 +2558,29 @@ get_names_for_var(Var *var, deparse_context *context,
}
else if (rte->rtekind == RTE_JOIN)
{
/*
* If it's an unnamed join, look at the expansion of the alias
* variable. If it's a simple reference to one of the input
* vars then recursively find the name of that var, instead.
* (This allows correct decompiling of cases where there are
* identically named columns on both sides of the join.)
* When it's not a simple reference, we have to just return
* the unqualified variable name (this can only happen with
* columns that were merged by USING or NATURAL clauses).
*/
if (var->varattno > 0)
{
Var *aliasvar;
aliasvar = (Var *) list_nth(rte->joinaliasvars,
var->varattno-1);
if (IsA(aliasvar, Var))
{
get_names_for_var(aliasvar, context,
schemaname, refname, attname);
return;
}
}
/* Unnamed join has neither schemaname nor refname */
*refname = NULL;
}