> -----Original Message----- > From: SPMLINGAM > Subject: postgresql performance > > Dear Friends, > I have a table with 50 lakhs records, the table has more > then 10 fields, i have primary key, i have select query with > count(*) without any condition, it takes 17 seconds. 17 seconds to scan 5 million records doesn't sound that bad to me. Postgresql does not store a count of records, and so it has to actually scan the table to count all the records. This was a design choice because select count(*) isn't usually used in a production system. > I have another one query which will do joins with other > small tables, it takes 47 seconds to give output, the result > has 2 lakhs records. the indexing is not used. I have > created one index with one field ( which i used in this > query, the field value has duplicates also ). You should post which version of Postgresql you are using, your table definition, and the output of EXPLAIN ANALYSE run on your query. If you have a lot of IO wait, you are most likely IO bound. When Postgresql is using a lot of CPU it is likely performing a sort or hashing. Pulling a large number of rows out of an even larger table can be difficult to do extremely quickly, but if you post the EXPLAIN ANALYZE output we would know if things could be improved or not. Dave -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://mail.postgresql.org/mj/mj_wwwusr?domain=postgresql.org&extra=pgsql-performance
