From d954439b175ebe346252b099047113c16734a26b Mon Sep 17 00:00:00 2001
From: Yugo Nagata <nagata@sraoss.co.jp>
Date: Mon, 21 Oct 2024 19:26:38 +0900
Subject: [PATCH] Prevent automatic index creation with set-returning function

Previously, a unique index is automatically created even when
a set-returning function is contained in FROM clause, but this
results in an error due to key duplication. Now, an index is
not created automatically when a relation other than table,
sub-query, or join is contained in FROM clause.

Issue (#99)
---
 createas.c          | 24 +++++++++++++++++-------
 expected/pg_ivm.out | 12 +++++++++++-
 sql/pg_ivm.sql      |  6 +++++-
 3 files changed, 33 insertions(+), 9 deletions(-)

diff --git a/createas.c b/createas.c
index 5b1b877..86b3bd2 100644
--- a/createas.c
+++ b/createas.c
@@ -1597,13 +1597,13 @@ get_primary_key_attnos_from_query(Query *query, List **constraintList)
 	{
 		RangeTblEntry *r = (RangeTblEntry*) lfirst(lc);
 		Bitmapset *key_attnos;
-		bool	has_pkey = true;
+		bool	has_no_pkey = false;
 
 		/* for subqueries, scan recursively */
 		if (r->rtekind == RTE_SUBQUERY)
 		{
 			key_attnos = get_primary_key_attnos_from_query(r->subquery, constraintList);
-			has_pkey = (key_attnos != NULL);
+			has_no_pkey = (key_attnos == NULL);
 		}
 		/* for tables, call get_primary_key_attnos */
 		else if (r->rtekind == RTE_RELATION)
@@ -1611,17 +1611,27 @@ get_primary_key_attnos_from_query(Query *query, List **constraintList)
 			Oid constraintOid;
 			key_attnos = get_primary_key_attnos(r->relid, false, &constraintOid);
 			*constraintList = lappend_oid(*constraintList, constraintOid);
-			has_pkey = (key_attnos != NULL);
+			has_no_pkey = (key_attnos == NULL);
 		}
-		/* for other RTEs, store NULL into key_attnos_list */
-		else
+		/*
+		 * Ignore join rels, because they are flatten later by
+		 * flatten_join_alias_vars(). Store NULL into key_attnos_list
+		 * as a dummy.
+		 */
+		else if (r->rtekind == RTE_JOIN)
+		{
 			key_attnos = NULL;
+		}
+		/* for other RTEs, we assume they have no candidate key */
+		else
+			has_no_pkey = true;
 
 		/*
-		 * If any table or subquery has no primary key or its pkey constraint is deferrable,
+		 * If any table or subquery has no primary key or its pkey constraint
+		 * is deferrable (i.e., get_primary_key_attnos returned NULL),
 		 * we cannot get key attributes for this query, so return NULL.
 		 */
-		if (!has_pkey)
+		if (has_no_pkey)
 			return NULL;
 
 		key_attnos_list = lappend(key_attnos_list, key_attnos);
diff --git a/expected/pg_ivm.out b/expected/pg_ivm.out
index e8798ee..363c927 100644
--- a/expected/pg_ivm.out
+++ b/expected/pg_ivm.out
@@ -1663,7 +1663,7 @@ HINT:  Create an index on the immv for efficient incremental maintenance.
            0
 (1 row)
 
---- subqueries
+--- subqueries: create an index
 SELECT create_immv('mv_idx6(i_a, i_b)', 'SELECT a.i, b.i FROM (SELECT * FROM base_a) a, (SELECT * FROM base_b) b');
 NOTICE:  created index "mv_idx6_index" on immv "mv_idx6"
  create_immv 
@@ -1671,6 +1671,16 @@ NOTICE:  created index "mv_idx6_index" on immv "mv_idx6"
            0
 (1 row)
 
+--- with set-returning function: no index
+SELECT create_immv('mv_idx7', 'SELECT i FROM base_a, generate_series(1,10)');
+NOTICE:  could not create an index on immv "mv_idx7" automatically
+DETAIL:  This target list does not have all the primary key columns, or this view does not contain GROUP BY or DISTINCT clause.
+HINT:  Create an index on the immv for efficient incremental maintenance.
+ create_immv 
+-------------
+           0
+(1 row)
+
 ROLLBACK;
 -- type that doesn't have default operator class for access method btree
 BEGIN;
diff --git a/sql/pg_ivm.sql b/sql/pg_ivm.sql
index d3c1a01..e2fbdea 100644
--- a/sql/pg_ivm.sql
+++ b/sql/pg_ivm.sql
@@ -662,8 +662,12 @@ SELECT create_immv('mv_idx3(i_a, i_b)', 'SELECT a.i, b.i FROM base_a a, base_b b
 SELECT create_immv('mv_idx4', 'SELECT j FROM base_a');
 SELECT create_immv('mv_idx5', 'SELECT a.i, b.j FROM base_a a, base_b b');
 
---- subqueries
+--- subqueries: create an index
 SELECT create_immv('mv_idx6(i_a, i_b)', 'SELECT a.i, b.i FROM (SELECT * FROM base_a) a, (SELECT * FROM base_b) b');
+
+--- with set-returning function: no index
+SELECT create_immv('mv_idx7', 'SELECT i FROM base_a, generate_series(1,10)');
+
 ROLLBACK;
 
 -- type that doesn't have default operator class for access method btree