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

1 files changed, 28 insertions, 0 deletions

diff --git a/src/test/modules/injection_points/sql/reindex_conc.sql b/src/test/modules/injection_points/sql/reindex_conc.sql
new file mode 100644
index 00000000000..6cf211e6d5d
--- /dev/null
+++ b/src/test/modules/injection_points/sql/reindex_conc.sql
@@ -0,0 +1,28 @@
+-- Tests for REINDEX CONCURRENTLY
+CREATE EXTENSION injection_points;
+
+-- Check safety of indexes with predicates and expressions.
+SELECT injection_points_set_local();
+SELECT injection_points_attach('reindex-conc-index-safe', 'notice');
+SELECT injection_points_attach('reindex-conc-index-not-safe', 'notice');
+
+CREATE SCHEMA reindex_inj;
+CREATE TABLE reindex_inj.tbl(i int primary key, updated_at timestamp);
+
+CREATE UNIQUE INDEX ind_simple ON reindex_inj.tbl(i);
+CREATE UNIQUE INDEX ind_expr ON reindex_inj.tbl(ABS(i));
+CREATE UNIQUE INDEX ind_pred ON reindex_inj.tbl(i) WHERE mod(i, 2) = 0;
+CREATE UNIQUE INDEX ind_expr_pred ON reindex_inj.tbl(abs(i)) WHERE mod(i, 2) = 0;
+
+REINDEX INDEX CONCURRENTLY reindex_inj.ind_simple;
+REINDEX INDEX CONCURRENTLY reindex_inj.ind_expr;
+REINDEX INDEX CONCURRENTLY reindex_inj.ind_pred;
+REINDEX INDEX CONCURRENTLY reindex_inj.ind_expr_pred;
+
+-- Cleanup
+SELECT injection_points_detach('reindex-conc-index-safe');
+SELECT injection_points_detach('reindex-conc-index-not-safe');
+DROP TABLE reindex_inj.tbl;
+DROP SCHEMA reindex_inj;
+
+DROP EXTENSION injection_points;