From 5bbdfa8a18dc56d3e64aa723a68e02e897cb5ec3 Mon Sep 17 00:00:00 2001
From: Michael Paquier
Date: Mon, 9 Sep 2024 13:49:36 +0900
Subject: Fix waits of REINDEX CONCURRENTLY for indexes with predicates or
 expressions

As introduced by f9900df5f94, a REINDEX CONCURRENTLY job done for an
index with predicates or expressions would set PROC_IN_SAFE_IC in its
MyProc->statusFlags, causing it to be ignored by other concurrent
operations.

Such concurrent index rebuilds should never be ignored, as a predicate
or an expression could call a user-defined function that accesses a
different table than the table where the index is rebuilt.

A test that uses injection points is added, backpatched down to 17.
Michail has proposed a different test, but I have added something
simpler with more coverage.

Oversight in f9900df5f949.

Author: Michail Nikolaev
Discussion: https://postgr.es/m/CANtu0oj9A3kZVduFTG0vrmGnKB+DCHgEpzOp0qAyOgmks84j0w@mail.gmail.com
Backpatch-through: 14
---
 src/backend/commands/indexcmds.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

(limited to 'src/backend')

diff --git a/src/backend/commands/indexcmds.c b/src/backend/commands/indexcmds.c
index c5a56c75f69..b987e023849 100644
--- a/src/backend/commands/indexcmds.c
+++ b/src/backend/commands/indexcmds.c
@@ -61,6 +61,7 @@
 #include "utils/builtins.h"
 #include "utils/fmgroids.h"
 #include "utils/guc.h"
+#include "utils/injection_point.h"
 #include "utils/inval.h"
 #include "utils/lsyscache.h"
 #include "utils/memutils.h"
@@ -3782,8 +3783,16 @@ ReindexRelationConcurrently(const ReindexStmt *stmt, Oid relationOid, const Rein
 		RestrictSearchPath();
 
 		/* determine safety of this index for set_indexsafe_procflags */
-		idx->safe = (indexRel->rd_indexprs == NIL &&
-					 indexRel->rd_indpred == NIL);
+		idx->safe = (RelationGetIndexExpressions(indexRel) == NIL &&
+					 RelationGetIndexPredicate(indexRel) == NIL);
+
+#ifdef USE_INJECTION_POINTS
+		if (idx->safe)
+			INJECTION_POINT("reindex-conc-index-safe");
+		else
+			INJECTION_POINT("reindex-conc-index-not-safe");
+#endif
+
 		idx->tableId = RelationGetRelid(heapRel);
 		idx->amId = indexRel->rd_rel->relam;
 
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