Re: amcheck: support for GiST

On Sat, Jan 31, 2026 at 2:17 PM Roman Khapov <rkhapov(at)yandex-team(dot)ru> wrote:

> >
> > Yeah, verify_common.c does require the header, but what I meant was that
> > verify_nbtree.c no longer needs it.
>
> Oh, thanks, now I see..
>
> Updated the patches.
>

I additionally tested the latest version (v2026-01-12-v2) -- and all looked
good to me.

testing performed:

1. Applied cleanly; built with --enable-cassert, make -C contrib/amcheck
check — all tests pass

2. Tested for 9 core GiST opclasses, on larger indexes (10M records), with
both heapallindexed=false and heapallindexed=true
(10M records, old macbook m1):

Opclass heapallindexed=false heapallindexed=true
-------------- -------------------- -------------------
point_ops 3.9s 5.9s
box_ops 6.3s 9.3s
circle_ops 5.5s 10.6s
poly_ops 5.8s 13.7s
inet_ops 0.6s 5.6s
range_ops 3.2s 6.9s
multirange_ops 2.4s 10.8s
tsvector_ops 3.8s 13.7s
tsquery_ops 0.3s 4.9s

3. Similarly, just to double-check, for extensions that use GiST:
- contrib modules tested: btree_gist, cube, hstore, ltree, pg_trgm, seg
(tested a single opclass for each; so 8 out of 30+ opclasses)
- skipped: intarray because it was annoyingly slow to build (looks like
O(n²)?)

4. Verified corruption detection works. Reproduction steps:

Setup (with data checksums disabled)

create table t as select point(random()*1000, random()*1000) c from
generate_series(1,50000);
create index t_idx on t using gist(c);
select pg_relation_filepath('t_idx'); -- e.g., base/5/16398

Stop server, corrupt index, start:

pg_ctl stop -D $PGDATA
python3 -c "
f = open('$PGDATA/base/5/16398', 'r+b')
f.seek(8192 + 24) # page 1, line pointer area
f.write(b'\xDE\xAD\xBE\xEF' * 8)
f.close()
"
pg_ctl start -D $PGDATA

And then we see an error as expected:

select gist_index_check('t_idx', false);
-- ERROR: invalid line pointer storage in index "t_idx"
-- DETAIL: Index tid=(1,20) lp_off=0, lp_len=0 lp_flags=0.

*****

Side note (general amcheck observation, not specific to this patch): the
existing amcheck TAP tests for heapam include corruption injection tests
(see 001_verify_heapam.pl). Similar tests for index checkers would be
valuable for amcheck -- but I think it's a broader effort beyond this
particular patch's scope.

The patch looks solid.

Nik