parul <i.parultyagi@xxxxxxxxx> wrote: > I have a index in a table. The value of the reltuples value in the > pg_class table for this index is less than the number of rows in > the table where the index is present. > For eg. if i have 800 rows in the table , the reltuples in the > pg_class for the index show the value as 769. > What are the scenarios under which this kind of behaviour occurs? The fine manual explains it here: http://www.postgresql.org/docs/9.0/interactive/catalog-pg-class.html To quote: | Number of rows in the table. This is only an estimate used by the | planner. It is updated by VACUUM, ANALYZE, and a few DDL commands | such as CREATE INDEX. Other operations which affect the number of rows in the table won't change this column, so it can be off by a bit until the next autovacuum or explicit operation which sets a new estimate. > Also iam not able to execute the queries involving the indexed > column in the where clause. Are you saying that you expect that a plan would have been chosen which would have used the index, but it is choosing some other plan? If so, your best bet is to present the actual query. http://wiki.postgresql.org/wiki/SlowQueryQuestions -Kevin -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
