From c293ba9effba68f17fec74d3ca0e8f900f3c8a53 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Thu, 8 Nov 2007 23:22:54 +0000
Subject: [PATCH] If an index depends on no columns of its table, give it a
dependency on the whole table instead, to ensure that it goes away when the
table is dropped. Per bug #3723 from Sam Mason.
Backpatch as far as 7.4; AFAICT 7.3 does not have the issue, because it doesn't
have general-purpose expression indexes and so there must be at least one
column referenced by an index.
---
src/backend/catalog/index.c | 26 +++++++++++++++++++++++++-
1 file changed, 25 insertions(+), 1 deletion(-)
diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c
index 0e76bc9800d..7f2bad8c0f6 100644
--- a/src/backend/catalog/index.c
+++ b/src/backend/catalog/index.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/catalog/index.c,v 1.286 2007/10/12 18:55:12 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/catalog/index.c,v 1.287 2007/11/08 23:22:54 tgl Exp $
*
*
* INTERFACE ROUTINES
@@ -41,6 +41,7 @@
#include "executor/executor.h"
#include "miscadmin.h"
#include "optimizer/clauses.h"
+#include "optimizer/var.h"
#include "parser/parse_expr.h"
#include "storage/procarray.h"
#include "storage/smgr.h"
@@ -723,6 +724,8 @@ index_create(Oid heapRelationId,
}
else
{
+ bool have_simple_col = false;
+
/* Create auto dependencies on simply-referenced columns */
for (i = 0; i < indexInfo->ii_NumIndexAttrs; i++)
{
@@ -733,8 +736,29 @@ index_create(Oid heapRelationId,
referenced.objectSubId = indexInfo->ii_KeyAttrNumbers[i];
recordDependencyOn(&myself, &referenced, DEPENDENCY_AUTO);
+
+ have_simple_col = true;
}
}
+
+ /*
+ * It's possible for an index to not depend on any columns of
+ * the table at all, in which case we need to give it a dependency
+ * on the table as a whole; else it won't get dropped when the
+ * table is dropped. This edge case is not totally useless;
+ * for example, a unique index on a constant expression can serve
+ * to prevent a table from containing more than one row.
+ */
+ if (!have_simple_col &&
+ !contain_vars_of_level((Node *) indexInfo->ii_Expressions, 0) &&
+ !contain_vars_of_level((Node *) indexInfo->ii_Predicate, 0))
+ {
+ referenced.classId = RelationRelationId;
+ referenced.objectId = heapRelationId;
+ referenced.objectSubId = 0;
+
+ recordDependencyOn(&myself, &referenced, DEPENDENCY_AUTO);
+ }
}
/* Store dependency on operator classes */
--
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