using sequential scan instead of index for join with a union

Hi, I am joining the union of three tables with another table. Postgresql uses the index when only two tables are in the union. If I add one more table to the union, it switches to seq scan. Apparently it also uses the index when only one table is joined. The SQL is: select * from ( SELECT 'NEWS'

Re: using sequential scan instead of index for join with a union

Hi Please check datatypes in union all part. Possible, notice.id or notice.mbct_id datatypes does not match with other tables. regards, Sergei

Analyze results in more expensive query plan

Hello, We have several select statements whose performance is greatly improved by deleting some stats from pg_statistic. With the stats present the database reaches 100% cpu at 13k queries per second. Without these stats, the same machine can handle over 29k queries per second. We were able rep

RE: Re: Re: Generic Plans for Prepared Statement are 158155 times slower than Custom Plans

Deepak, I changed the datatype from citext to text and now everything works fine. The data distribution is same, plan is same, yet there is a huge performance degradation when citext is used instead of text. However the business case requires case insensitive string handling. I am looking forward

Re: using sequential scan instead of index for join with a union

Hi, Sergei Thanks! I've just double checked and they are the same: \d notice id | bigint | | not null | nextval('notice_id_seq'::regclass) mbct_id| bigint | | | \d news id | bigint

Re: Analyze results in more expensive query plan

Jeremy Altavilla writes: > We have several select statements whose performance is greatly improved by > deleting some stats from pg_statistic. You might have better results by setting up some "extended stats" for the combination of bag_type columns that this query depends on. Per your descriptio