On 07/13/2010 06:48 AM, Elias Ghanem wrote:
Hi, I have table "ARTICLE" containing a String a field "STATUS" that represents a number in binary format (for ex: 10011101). My application issues queries with where conditions that uses BITAND operator on this field (for ex: select * from article where status & 4 = 4). Thus i'm facing performance problemes with these select queries: the queries are too slow. Since i'm using the BITAND operator in my conditions, creating an index on the status filed is useless and since the second operator variable (status & 4 = 4; status & 8 = 8; status & 16 = 16...) a functional index is also usless (because a functional index require the use of a function that accept only table column as input parameter: constants are not accepted). So is there a way to enhance the performance of these queries? Thanks, Elias
How many flags are there? If its not too many you could make a separate column for each... but then that would be lots of indexes too... One other thought I had was to make it a text column, turn the flags into words (space separated) and use full text indexes. I played around with int's and string's but I couldnt find a way using the & operator. -Andy -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
