Hi Szymon,
yes I have indexes on both columns (one in each table) which I am using
for join operation.
Am 19.09.2014 14:04, schrieb Szymon Guz:
On 19 September 2014 13:51, Björn Wittich <bjoern_witt...@gmx.de
<mailto:bjoern_witt...@gmx.de>> 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?
Szymon
