I don't understand this explain output
От | Ron Arts |
---|---|
Тема | I don't understand this explain output |
Дата | |
Msg-id | 4A1BA903.8020300@neonova.nl обсуждение исходный текст |
Ответы |
Re: I don't understand this explain output
Re: I don't understand this explain output |
Список | pgsql-novice |
Hi, I am looking at a very simple query (select * from queue), which takes forever to finish. I don't understand the output that explain tells me: m=# explain select * from queue; QUERY PLAN ------------------------------------------------------------ Seq Scan on queue (cost=0.00..635477.00 rows=1 width=402) (1 row) The cost seems to be very high. It's a small table (only 23 rows) and has not seen many modifications since the table was initially filled. OTOH many individual records are updated every minute. If I look at anopther table in the same database: m=# explain select * from contact; QUERY PLAN ------------------------------------------------------------- Seq Scan on contact (cost=0.00..183.14 rows=614 width=411) (1 row) and this query finishes very quickly (614 rows). Why would a simple query be so very costly? Thanks, Ron Arts -- NeoNova BV innovatieve internetoplossingen http://www.neonova.nl Science Park 140 1098 XG Amsterdam info: 020-5611300 servicedesk: 020-5611302 fax: 020-5611301 KvK Amsterdam 34151241 Op dit bericht is de volgende disclaimer van toepassing: http://www.neonova.nl/maildisclaimer
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