Stats on new tables
От | Michael Richards |
---|---|
Тема | Stats on new tables |
Дата | |
Msg-id | Pine.BSF.4.10.9910241553001.46045-100000@scifair.acadiau.ca обсуждение исходный текст |
Ответы |
Re: [SQL] Stats on new tables
Re: [SQL] Stats on new tables |
Список | pgsql-sql |
I think I've found something of interest. When I create a new table, the plan for it believes that the table contains 2 rows, not 0. Also, since the engine knows when we run an insert, and also knows how many rows a delete nukes, wouldn't it be better to update the stats after every select and delete? -Michael equipment=> CREATE TABLE xuserid( equipment-> oldid varchar(12), equipment-> newid int4, equipment-> PRIMARY KEY (oldid,newid) equipment-> ); NOTICE: CREATE TABLE/PRIMARY KEY will create implicit index 'xuserid_pkey' for table 'xuserid' CREATE equipment=> \d xuserid_pkey Table = xuserid_pkey +----------------------------------+----------------------------------+-------+ | Field | Type | Length| +----------------------------------+----------------------------------+-------+ | oldid | varchar() | 12 | | newid | int4 | 4 | +----------------------------------+----------------------------------+-------+ equipment=> explain select * from xuserid where newid=859; NOTICE: QUERY PLAN: Seq Scan on xuserid (cost=43.00 rows=2 width=16) EXPLAIN equipment=> vacuum analyze; VACUUM equipment=> explain select * from xuserid where newid=859; NOTICE: QUERY PLAN: Seq Scan on xuserid (cost=0.00 rows=0 width=16) EXPLAIN
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