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Date: Tue, 12 Nov 2024 19:01:47 +0900
From: Masahiro Ikeda <ikedamsh@oss.nttdata.com>
To: pgsql-hackers@postgresql.org
Subject: Fix to increment the index scan counter for the bloom filter index
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Hi,

I noticed that the bloom filter index forgets to increment the index 
scan counter
while reviewing the skip scan patch [1]. It seems this was simply 
overlooked in
the implementation. What do you think?


# A test case:
## HEAD: 3f323eba89fb

CREATE EXTENSION bloom ;
CREATE TABLE tbloom AS
    SELECT
      (random() * 1000000)::int as i1,
      (random() * 1000000)::int as i2,
      (random() * 1000000)::int as i3,
      (random() * 1000000)::int as i4,
      (random() * 1000000)::int as i5,
      (random() * 1000000)::int as i6
    FROM
   generate_series(1,10000000);
CREATE INDEX bloomidx ON tbloom USING bloom (i1, i2, i3, i4, i5, i6);
ANALYZE;

psql=# SELECT * FROM pg_stat_user_indexes ;
-[ RECORD 1 ]-+---------
relid         | 16384
indexrelid    | 16398
schemaname    | public
relname       | tbloom
indexrelname  | bloomidx
idx_scan      | 0
last_idx_scan |
idx_tup_read  | 0
idx_tup_fetch | 0

psql=# SET enable_seqscan = off;
psql=# EXPLAIN ANALYZE SELECT * FROM tbloom WHERE i2 = 898732 AND i5 = 
123451;

postgres=# SELECT * FROM pg_stat_user_indexes ;
-[ RECORD 1 ]-+---------
relid         | 16384
indexrelid    | 16398
schemaname    | public
relname       | tbloom
indexrelname  | bloomidx
idx_scan      | 0                       # was not incremented
last_idx_scan |                         #
idx_tup_read  | 2362                    # was incremented. It indicates 
that an index scan was executed
idx_tup_fetch | 0


## HEAD with the v1 patch

-- after EXPLAIN ANALYZE ...
postgres=# SELECT * FROM pg_stat_user_indexes ;
-[ RECORD 1 ]-+------------------------------
relid         | 16395
indexrelid    | 16398
schemaname    | public
relname       | tbloom
indexrelname  | bloomidx
idx_scan      | 1                                   # was incremented 
too
last_idx_scan | 2024-11-12 18:15:39.270747+09       #
idx_tup_read  | 2503                                #
idx_tup_fetch | 0


[1] 
https://www.postgresql.org/message-id/flat/CAH2-Wz%3DM_8UCPpD5GQuJXmQZ6xePwhVSss38TmkBAwic12VvCg%40mail.gmail.com#ffef7ecf393d0008c5ded2d2184a71f9

Regards,
-- 
Masahiro Ikeda
NTT DATA CORPORATION
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