try this query : SELECT rid.dokumnr as d1 ,dok.dokumnr as d2 FROM rid left join dok on rid.dokumnr = dok.dokumnr where dok.dokumnr is null;
> Tables: > > CREATE TABLE dok ( dokumnr NUMERIC(12), > CONSTRAINT dok_pkey PRIMARY KEY (dokumnr) ); > CREATE TABLE rid ( dokumnr NUMERIC(12) ); > CREATE INDEX rid_dokumnr_idx ON rid (dokumnr); > > Query: > > SELECT dokumnr FROM rid WHERE dokumnr NOT IN > (select dokumnr FROM dok); > > runs VERY slowly in Postgres. It uses the following query plan: > > Seq Scan on rid (cost=0.00..28698461.07 rows=32201 width=14) > Filter: (NOT (subplan)) > SubPlan > -> Seq Scan on dok (cost=0.00..864.29 rows=10729 width=14) > > In Microsoft Visual FoxPro this query runs fast. FoxPro uses indexes speed > up the query by comparing bitmaps. > > Is it possible to speed up this query is Postgres ? How to force Postgres > to use indexes for this query ? > > Andrus > > > > ---------------------------(end of broadcast)--------------------------- > TIP 2: you can get off all lists at once with the unregister command > (send "unregister YourEmailAddressHere" to [EMAIL PROTECTED]) -- ________________________________________________________ Krasimir Dimitrov IT Department AII Data Processing Ltd., 16 Ivan Vazov Str, Sofia 1000, Bulgaria Phone: +359 2 9376 352 E-mail: [EMAIL PROTECTED] http://www.see-news.com ---------------------------(end of broadcast)--------------------------- TIP 9: the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match
