Thread: INSERT extremely slow with large data sets (fwd)
Hi Everyone, I am using PostgreSQL 7.3.2 and have used earlier versions (7.1.x onwards) and with all of them I noticed same problem with INSERTs when there is a large data set. Just to so you guys can compare time it takes to insert one row into a table when there are only few rows present and when there are thousands: Rows Present Start Time Finish Time ------------------------------------------------------------ 100 1068790804.12 1068790804.12 1000 1068790807.87 1068790807.87 5000 1068790839.26 1068790839.27 10000 1068790909.24 1068790909.26 20000 1068791172.82 1068791172.85 30000 1068791664.06 1068791664.09 40000 1068792369.94 1068792370.0 50000 1068793317.53 1068793317.6 60000 1068794369.38 1068794369.47 As you can see if takes awfully lots of time for me just to have those values inserted. Now to make a picture a bit clearer for you this table has lots of information in there, about 25 columns. Also there are few indexes that I created so that the process of selecting values from there is faster which by the way works fine. Selecting anything takes under 5 seconds. Any help would be greatly appreciated even pointing me in the right direction where to ask this question. By the way I designed the database this way as my application that uses PGSQL a lot during the execution so there was a huge need for fast SELECTs. Our experiments are getting larger and larger every day so fast inserts would be good as well. Just to note those times above are of INSERTs only. Nothing else done that would be included in those times. Machine was also free and that was the only process running all the time and the machine was Intel(R) Pentium(R) 4 CPU 2.40GHz. Regards, Slavisa
On Fri, 14 Nov 2003 20:38:33 +1100 (EST) Slavisa Garic <Slavisa.Garic@infotech.monash.edu.au> wrote: > Any help would be greatly appreciated even pointing me in the right > direction where to ask this question. By the way I designed the > database this way as my application that uses PGSQL a lot during the > execution so there was a huge need for fast SELECTs. Our experiments > are getting larger and larger every day so fast inserts would be good > as well. > First, you need to upgrade to 7.3.4, 7.4 is prefable if a dump/reload is not too bad. Standard set of questions: 1. Any foreign keys 2. are these inserts batched into transactions 3. CPU usage? 4. OS? 5. PG config? [shared_buffers, effective_cache_size, etc] 6. IO saturation? Also, try searching the archives. lots of juicy info there too. -- Jeff Trout <jeff@jefftrout.com> http://www.jefftrout.com/ http://www.stuarthamm.net/
Slavisa Garic wrote: > Hi Everyone, > I am using PostgreSQL 7.3.2 and have used earlier versions (7.1.x > onwards) > and with all of them I noticed same problem with INSERTs when there is > a > large data set. Just to so you guys can compare time it takes to insert > one row into a table when there are only few rows present and when > there > are thousands: Try running VACUUM ANALYZE periodically during inserts. I found this to help. George Essig
Does VACUUM ANALYZE help with the analysis or it also speeds up the process. I know i could try that before I ask but experiment is running now and I am too curious to wait :), Anyway thanks for the hint, Slavisa On Fri, 14 Nov 2003, George Essig wrote: > Slavisa Garic wrote: > > > Hi Everyone, > > > I am using PostgreSQL 7.3.2 and have used earlier versions (7.1.x > > onwards) > > and with all of them I noticed same problem with INSERTs when there is > > a > > large data set. Just to so you guys can compare time it takes to insert > > one row into a table when there are only few rows present and when > > there > > are thousands: > > Try running VACUUM ANALYZE periodically during inserts. I found this to help. > > George Essig > >
--- Slavisa Garic <Slavisa.Garic@infotech.monash.edu.au> wrote: > Does VACUUM ANALYZE help with the analysis or it also speeds up the > process. I know i could try that before I ask but experiment is running > now and I am too curious to wait :), > > Anyway thanks for the hint, > Slavisa > VACUUM ANALYZE will reclaim disk space and update statistics used by the optimizer to help execute queries faster. This could speed up your inserts. See http://www.postgresql.org/docs/7.3/static/sql-vacuum.html. George Essig
On Sat, Nov 15, 2003 at 05:13:38AM -0800, George Essig wrote:
>
> VACUUM ANALYZE will reclaim disk space and update statistics used
Strictly speaking, it does not reclaim disk space. It merely marks
it as available, assuming you have enough room in your free space
map. VACUUM FULL reclaims disk space, i.e. it compacts the data
files and returns that space to the operating system.
A
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