Currently following query does not use an index:
t-ishii@localhost: psql -p 5433 test
Pager usage is off.
psql (9.6.3)
Type "help" for help.
test=# explain select * from pgbench_accounts where aid*100 < 10000;
QUERY PLAN
------------------------------------------------------------------------
Seq Scan on pgbench_accounts (cost=0.00..3319.00 rows=33333 width=97)
Filter: ((aid * 100) < 10000)
(2 rows)
While following one does use the index.
test=# explain select * from pgbench_accounts where aid < 10000/100;
QUERY PLAN
--------------------------------------------------------------------------------------------------
Index Scan using pgbench_accounts_pkey on pgbench_accounts (cost=0.29..11.08
rows=102 width=97)
Index Cond: (aid < 100)
(2 rows)
Is it worth to make our optimizer a little bit smarter to convert the
the first query into the second form?
Best regards,
--
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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