On 19 September 2014 13:51, Björn Wittich <Bjoern_Wittich@xxxxxx> wrote:
Hi mailing list,
I am relatively new to postgres. I have a table with 500 coulmns and about 40 mio rows. I call this cache table where one column is a unique key (indexed) and the 499 columns (type integer) are some values belonging to this key.
Now I have a second (temporary) table (only 2 columns one is the key of my cache table) and I want do an inner join between my temporary table and the large cache table and export all matching rows. I found out, that the performance increases when I limit the join to lots of small parts.
But it seems that the databases needs a lot of disk io to gather all 499 data columns.
Is there a possibilty to tell the databases that all these colums are always treated as tuples and I always want to get the whole row? Perhaps the disk oraganization could then be optimized?
Hi,
do you have indexes on the columns you use for joins?
do you have indexes on the columns you use for joins?
Szymon
