And... it was a rookie mistake. In answering the last question I once again looked at the database and realized there was an index missing! Swear it has been there before (and I should have double-checked sooner). Added the index and now we're moving right along.
Thanks for all leads everyone sent me. Learned a lot about Postgresql today. --Ray ----- Original Message ----- > From: "Ray Cote" <rgac...@appropriatesolutions.com> > To: "Jeff Janes" <jeff.ja...@gmail.com> > Cc: pgsql-general@postgresql.org > Sent: Thursday, June 6, 2013 5:12:51 PM > Subject: Re: [GENERAL] Database performs massive reads when I'm doing > writes. > It is Postmaster itself: > 11068 - 315.9M 136K 0K 85% postmaster > 11000 - 56808K 8K 0K 15% postmaster > 11003 - 0K 80K 0K 0% postmaster > 11004 - 0K 24K 0K 0% postmaster > 11067 - 0K 0K 0K 0% load_rets.py > The above are the atop lines for just postmaster. This is a 10s > snapshot so you can see lots of read activity. > The load_rets.py task is the Python script loading the database. > --Ray > ----- Original Message ----- > > From: "Jeff Janes" <jeff.ja...@gmail.com> > > > To: "Ray Cote" <rgac...@appropriatesolutions.com> > > > Cc: pgsql-general@postgresql.org > > > Sent: Thursday, June 6, 2013 4:05:28 PM > > > Subject: Re: [GENERAL] Database performs massive reads when I'm > > doing > > writes. > > > On Thu, Jun 6, 2013 at 9:53 AM, Ray Cote < > > rgac...@appropriatesolutions.com > wrote: > > > > Hello: > > > > > > I have a PostgreSQL 9.0.3 database that has suddenly started > > > exhibiting odd read behavior. > > > > > > The version number is: > > > > > > "PostgreSQL 9.0.3 on x86_64-unknown-linux-gnu, compiled by GCC > > > gcc > > > (GCC) 4.1.2 20080704 (Red Hat 4.1.2-50), 64-bit" > > > > > > This was compiled from source about a year ago and has been > > > running > > > just fine. > > > > > > The database feeds a very low-volume web site (a few hits per > > > minute). > > > > > > Starting a few days ago we started to see a strange behavior > > > where > > > writing to the database causes massive read operations. > > > > > > For example, I have a table that needs to be updated every night > > > (about 20,000 rows). > > > > > > Using Django ORM, we update them one item at a time. > > > > > > Usually the overall process takes a few minutes; it is now taking > > > hours (like over 15 hours). > > > > > > Running atop, we're seeing Read Disk values in the range of > > > 147.2M/10s and Write Disk values in the range of 16K/10s. > > > > > > Together, the Disk throughput is in the high 90% and frequently > > > hits > > > 100%. > > > > > Which specific processes are using the disk? (on my atop, if I hit > > 'c' it will change mode to show me the entire so-called "command > > line", which will let you know if the culprit is a vacuum worker, > > the checkpointer, or someone else). > > > Cheers, > > > Jeff > > -- > Ray Cote, President Appropriate Solutions, Inc. > We Build Software > www.AppropriateSolutions.com 603.924.6079 -- Ray Cote, President Appropriate Solutions, Inc. We Build Software www.AppropriateSolutions.com 603.924.6079
