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Fixing PostgreSQL corruption with Rails?

Posted by Sun, 06 Aug 2006 00:16:00 GMT

3 comments Latest by Robert Treat Tue, 08 Aug 2006 17:26:04 GMT

People have been emailing me to let me know that the search on my blog was broken. Today I finally set out to fix the problem, which looked like a complex issue with my PostgreSQL database. I’m not sure how long ago it started so I am not sure what was the cause at the moment. If you did a search on my blog you’d get an application error and behind the scenes, you would see the following error.

PGError: ERROR:  missing chunk number 0 for toast value 58441

Eek!

So, I tried to REINDEX the table and it didn’t solve the problem… so I started poking around with different types of queries to see what I could do to generate the error again. Didn’t take me long to figure out that it had something to do with the body column in the contents table.


db_name=# SELECT count(id) FROM contents WHERE body ~* 'postgresql' LIMIT 20;
ERROR:  missing chunk number 0 for toast value 58441

db_name_=# SELECT count(id) FROM contents WHERE excerpt ~* 'postgresql' LIMIT 20;
 count 
-------
     0
(1 row)

What am I to do? I did some googling (and go figure… the error being returned was caught on my blog by google)... which was amusing.

In the #postgresql channel on freenode they recommended that I try and find the specific row in the table that was causing this error. I decided to just run a for loop in script/console on the Content object in Typo and print out the name of each record until it gave me an error.


for i in 1..30000
  puts Content.find( i ).title
  i =+ 1
end

This began to print out titles of older blog entries and sure enough… the loop died when it hit the following error. :-)


  PostgreSQL sequences in Rails
  When TSearch2 Met AJAX
  ActiveRecord::StatementInvalid: PGError: ERROR:  missing chunk number 0 for toast value 58441
  : SELECT * FROM contents WHERE (contents.id = 1678)  LIMIT 1
          from /usr/local/lib/ruby/gems/1.8/gems/activerecord-1.13.1/lib/active_record/connection_adapters/abstract_adapter.rb:88:in `log'
          from /usr/local/lib/ruby/gems/1.8/gems/activerecord-1.13.1/lib/active_record/connection_adapters/postgresql_adapter.rb:137:in `execute'
          from /usr/local/lib/ruby/gems/1.8/gems/activerecord-1.13.1/lib/active_record/connection_adapters/postgresql_adapter.rb:351:in `select'
          from /usr/local/lib/ruby/gems/1.8/gems/activerecord-1.13.1/lib/active_record/connection_adapters/postgresql_adapter.rb:118:in `select_all'
          from /usr/local/lib/ruby/gems/1.8/gems/activerecord-1.13.1/lib/active_record/base.rb:431:in `find_by_sql'
          from /usr/local/lib/ruby/gems/1.8/gems/activerecord-1.13.1/lib/active_record/base.rb:395:in `find'
          from /usr/local/lib/ruby/gems/1.8/gems/activerecord-1.13.1/lib/active_record/base.rb:393:in `find'
          from /usr/local/lib/ruby/gems/1.8/gems/activerecord-1.13.1/lib/active_record/base.rb:409:in `find'
          from (irb):23
          from (irb):22
  >> exit

15.seconds.later I logged into psql and ran DELETE FROM contents WHERE id = 1678... and all is well!