On Thu, Jan 7, 2010 at 3:14 PM, Alvaro Herrera <alvherre@xxxxxxxxxxxxxxxxx> wrote: > Lefteris escribió: >> Yes, I am reading the plan wrong! I thought that each row from the >> plan reported the total time for the operation but it actually reports >> the starting and ending point. >> >> So we all agree that the problem is on the scans:) >> >> So the next question is why changing shared memory buffers will fix >> that? i only have one session with one connection, do I have like many >> reader workers or something? > > No amount of tinkering is going to change the fact that a seqscan is the > fastest way to execute these queries. Even if you got it to be all in > memory, it would still be much slower than the other systems which, I > gather, are using columnar storage and thus are perfectly suited to this > problem (unlike Postgres). The talk about "compression ratios" caught > me by surprise until I realized it was columnar stuff. There's no way > you can get such high ratios on a regular, row-oriented storage. > > -- > Alvaro Herrera http://www.CommandPrompt.com/ > PostgreSQL Replication, Consulting, Custom Development, 24x7 support > I am aware of that and I totally agree. I would not expect from a row store to have the same performance with a column. I was just trying to double check that all settings are correct because usually you have difference of seconds and minutes between column-rows, not seconds and almost an hour (for queries Q2-Q8). I think what you all said was very helpful and clear! The only part that I still disagree/don't understand is the shared_buffer option:)) Lefteris -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
