Forgive me if this has been already discussed somewhere.
When a transaction aborts, it seems a BRIN index leaves summary data
which is not valid any more. Is this an expected behavior? I guess
the answer is yes, because it does not affect correctness of a query
result, but I would like to make sure.
Second question is when the wrong summary data is gone? It seems
vacuum does not help. Do I have to recreate the index (or reindex)?
test=# begin;
BEGIN
test=# insert into t1 values(1000001);
INSERT 0 1
test=# SELECT * FROM brin_page_items(get_raw_page('brinidx', 2),'brinidx');
itemoffset | blknum | attnum | allnulls | hasnulls | placeholder |
value
------------+--------+--------+----------+----------+-------------+---------------------
1 | 0 | 1 | f | f | f | {1 .. 28928}
2 | 128 | 1 | f | f | f | {28929 ..
57856}
3 | 256 | 1 | f | f | f | {57857 ..
86784}
[snip]
34 | 4224 | 1 | f | f | f | {954625 ..
983552}
35 | 4352 | 1 | f | f | f | {983553 ..
1000001}
(35 rows)
test=# abort;
ROLLBACK
test=# SELECT * FROM brin_page_items(get_raw_page('brinidx', 2),'brinidx');
itemoffset | blknum | attnum | allnulls | hasnulls | placeholder |
value
------------+--------+--------+----------+----------+-------------+---------------------
1 | 0 | 1 | f | f | f | {1 .. 28928}
2 | 128 | 1 | f | f | f | {28929 ..
57856}
3 | 256 | 1 | f | f | f | {57857 ..
86784}
[snip]
34 | 4224 | 1 | f | f | f | {954625 ..
983552}
35 | 4352 | 1 | f | f | f | {983553 ..
1000001}
(35 rows)
test=# vacuum t1;
VACUUM
test=# SELECT * FROM brin_page_items(get_raw_page('brinidx', 2),'brinidx');
itemoffset | blknum | attnum | allnulls | hasnulls | placeholder |
value
------------+--------+--------+----------+----------+-------------+---------------------
1 | 0 | 1 | f | f | f | {1 .. 28928}
2 | 128 | 1 | f | f | f | {28929 ..
57856}
3 | 256 | 1 | f | f | f | {57857 ..
86784}
[snip]
33 | 4096 | 1 | f | f | f | {925697 ..
954624}
34 | 4224 | 1 | f | f | f | {954625 ..
983552}
35 | 4352 | 1 | f | f | f | {983553 ..
1000001}
(35 rows)
test=# select max(i) from t1;
max
---------
1000000
(1 row)
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese:http://www.sraoss.co.jp
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