Re: Using read_stream in index vacuum

On Tue, Mar 18, 2025 at 11:12 AM Melanie Plageman
<melanieplageman(at)gmail(dot)com> wrote:
>
> I'm looking at 0001 with the intent of committing it soon. Today I've
> just been studying the test with the injection points.
>
> My main thought is that you should rename the injection points to
> something more descriptive. We want to make it clear why there are
> two. Also nbtree-vacuum-2 is actually where we wait the first
> iteration of the loop, so that is confusing.

I actually think you could do the test with one injection point and
just wait on it twice

diff --git a/src/backend/access/nbtree/nbtree.c
b/src/backend/access/nbtree/nbtree.c
index fe7084edacd..79f4323f887 100644
--- a/src/backend/access/nbtree/nbtree.c
+++ b/src/backend/access/nbtree/nbtree.c
@@ -1091,7 +1091,6 @@ btvacuumscan(IndexVacuumInfo *info,
IndexBulkDeleteResult *stats,

/* In 007_vacuum_btree test we need to coordinate two
distinguishable points here */
INJECTION_POINT("nbtree-vacuum-1");
- INJECTION_POINT("nbtree-vacuum-2");

p.last_exclusive = num_pages;

diff --git a/src/test/modules/test_misc/t/007_vacuum_btree.pl
b/src/test/modules/test_misc/t/007_vacuum_btree.pl
index 2c69d2b477d..6d5f474b99a 100644
--- a/src/test/modules/test_misc/t/007_vacuum_btree.pl
+++ b/src/test/modules/test_misc/t/007_vacuum_btree.pl
@@ -37,7 +37,7 @@ $node->safe_psql('postgres', 'CREATE EXTENSION
injection_points;');

# From this point, vacuum worker will wait at startup.
$node->safe_psql('postgres',
- "SELECT injection_points_attach('nbtree-vacuum-2', 'wait');");
+ "SELECT injection_points_attach('nbtree-vacuum-1', 'wait');");

my $psql_session = $node->background_psql('postgres');

@@ -51,10 +51,7 @@ $psql_session->query_until(
));

# Wait until an vacuum worker starts.
-$node->wait_for_event('client backend', 'nbtree-vacuum-2');
-
-$node->safe_psql('postgres',
- "SELECT injection_points_attach('nbtree-vacuum-1', 'wait');");
+$node->wait_for_event('client backend', 'nbtree-vacuum-1');

# Here's the key point of a test: during vacuum we add some page splits.
# This will force vacuum into doing another scan thus reseting read stream.
@@ -62,18 +59,16 @@ $node->safe_psql('postgres',
"insert into a select x from generate_series(1,3000) x;");

$node->safe_psql('postgres',
- "SELECT injection_points_detach('nbtree-vacuum-2');");
-$node->safe_psql('postgres',
- "SELECT injection_points_wakeup('nbtree-vacuum-2');");
+ "SELECT injection_points_wakeup('nbtree-vacuum-1');");

-# Observe that second scan is reached.
$node->wait_for_event('client backend', 'nbtree-vacuum-1');

-$node->safe_psql('postgres',
- "SELECT injection_points_detach('nbtree-vacuum-1');");
$node->safe_psql('postgres',
"SELECT injection_points_wakeup('nbtree-vacuum-1');");

+$node->safe_psql('postgres',
+ "SELECT injection_points_detach('nbtree-vacuum-1');");
+
ok($psql_session->quit);

done_testing();