Fix assertion if index is dropped during REFRESH CONCURRENTLY

When assertions are disabled, the built SQL statement is invalid and
you get a "syntax error". So this isn't a serious problem, but let's
avoid the assertion failure.

Backpatch to all supported versions.

Reviewed-by: Noah Misch

2 files changed, 33 insertions, 0 deletions

diff --git a/src/test/regress/expected/matview.out b/src/test/regress/expected/matview.out
index 93d6e23b4a0..18c5b866a5a 100644
--- a/src/test/regress/expected/matview.out
+++ b/src/test/regress/expected/matview.out
@@ -572,6 +572,22 @@ REFRESH MATERIALIZED VIEW mvtest_mv_foo;
 REFRESH MATERIALIZED VIEW CONCURRENTLY mvtest_mv_foo;
 DROP OWNED BY regress_user_mvtest CASCADE;
 DROP ROLE regress_user_mvtest;
+-- Concurrent refresh requires a unique index on the materialized
+-- view. Test what happens if it's dropped during the refresh.
+CREATE OR REPLACE FUNCTION mvtest_drop_the_index()
+  RETURNS bool AS $$
+BEGIN
+  EXECUTE 'DROP INDEX IF EXISTS mvtest_drop_idx';
+  RETURN true;
+END;
+$$ LANGUAGE plpgsql;
+CREATE MATERIALIZED VIEW drop_idx_matview AS
+  SELECT 1 as i WHERE mvtest_drop_the_index();
+NOTICE:  index "mvtest_drop_idx" does not exist, skipping
+CREATE UNIQUE INDEX mvtest_drop_idx ON drop_idx_matview (i);
+REFRESH MATERIALIZED VIEW CONCURRENTLY drop_idx_matview;
+ERROR:  could not find suitable unique index on materialized view
+DROP MATERIALIZED VIEW drop_idx_matview; -- clean up
 -- make sure that create WITH NO DATA works via SPI
 BEGIN;
 CREATE FUNCTION mvtest_func()
diff --git a/src/test/regress/sql/matview.sql b/src/test/regress/sql/matview.sql
index 1d690254641..385e48e9e78 100644
--- a/src/test/regress/sql/matview.sql
+++ b/src/test/regress/sql/matview.sql
@@ -231,6 +231,23 @@ REFRESH MATERIALIZED VIEW CONCURRENTLY mvtest_mv_foo;
 DROP OWNED BY regress_user_mvtest CASCADE;
 DROP ROLE regress_user_mvtest;
 
+-- Concurrent refresh requires a unique index on the materialized
+-- view. Test what happens if it's dropped during the refresh.
+CREATE OR REPLACE FUNCTION mvtest_drop_the_index()
+  RETURNS bool AS $$
+BEGIN
+  EXECUTE 'DROP INDEX IF EXISTS mvtest_drop_idx';
+  RETURN true;
+END;
+$$ LANGUAGE plpgsql;
+
+CREATE MATERIALIZED VIEW drop_idx_matview AS
+  SELECT 1 as i WHERE mvtest_drop_the_index();
+
+CREATE UNIQUE INDEX mvtest_drop_idx ON drop_idx_matview (i);
+REFRESH MATERIALIZED VIEW CONCURRENTLY drop_idx_matview;
+DROP MATERIALIZED VIEW drop_idx_matview; -- clean up
+
 -- make sure that create WITH NO DATA works via SPI
 BEGIN;
 CREATE FUNCTION mvtest_func()