Re: [JDBC] Prepared Statements and large where-id-in constant blocks?
От | Oliver Jowett |
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Тема | Re: [JDBC] Prepared Statements and large where-id-in constant blocks? |
Дата | |
Msg-id | 408491B1.20800@opencloud.com обсуждение исходный текст |
Ответ на | Re: [JDBC] Prepared Statements and large where-id-in constant blocks? (Oliver Jowett <oliver@opencloud.com>) |
Ответы |
Re: [JDBC] Prepared Statements and large where-id-in constant blocks?
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Список | pgsql-sql |
Oliver Jowett wrote: > The CMP layer could perhaps use the = ANY array syntax and setArray() > (note that setArray() in the current driver needs fixing, I have an old > patch to do this): > > SELECT t1.attr1 FROM t1 where t1.id = ANY (?) Unfortunately a bit of experimentation indicates that the planner doesn't do anything clever with ANY + constant array values (at least in 7.4.1 which is what I have to hand): > test=> explain select * from test_array where i in (1,2,3,4,5); > QUERY PLAN > ------------------------------------------------------------------------------------------------------------------------------------------------------- > Index Scan using test_array_pkey, test_array_pkey, test_array_pkey, test_array_pkey, test_array_pkey on test_array (cost=0.00..15.12rows=5 width=4) > Index Cond: ((i = 1) OR (i = 2) OR (i = 3) OR (i = 4) OR (i = 5)) > (2 rows) > > test=> explain select * from test_array where i = any ('{1,2,3,4,5}'::integer[]); > QUERY PLAN > ---------------------------------------------------------------- > Seq Scan on test_array (cost=0.00..807.80 rows=10240 width=4) > Filter: (i = ANY ('{1,2,3,4,5}'::integer[])) > (2 rows) > > test=> select version(); > version > ------------------------------------------------------------------------------------------------------------------ > PostgreSQL 7.4.1 on i386-pc-linux-gnu, compiled by GCC i386-linux-gcc (GCC) 3.3.3 20040110 (prerelease) (Debian) > (1 row) -O
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