Three interesting patches:

• On 27th of March, Robert Haas committed patch:

  New GUC, track_iotiming, to track I/O timings.
   
  Currently, the only way to see the numbers this gathers is via
  EXPLAIN (ANALYZE, BUFFERS), but the plan is to add visibility through
  the stats collector and pg_stat_statements in subsequent patches.
   
  Ants Aasma, reviewed by Greg Smith, with some further changes by me.

• On 27th of March, Robert Haas committed patch:

  Expose track_iotiming information via pg_stat_statements.
   
  Ants Aasma, reviewed by Greg Smith, with very minor tweaks by me.

• On 29th of March, Tom Lane committed patch:

  Improve contrib/pg_stat_statements to lump "similar" queries together.
   
  pg_stat_statements now hashes selected fields of the analyzed parse tree
  to assign a "fingerprint" to each query, and groups all queries with the
  same fingerprint into a single entry in the pg_stat_statements view.
  In practice it is expected that queries with the same fingerprint will be
  equivalent except for values of literal constants.  To make the display
  more useful, such constants are replaced by "?" in the displayed query
  strings.
   
  This mechanism currently supports only optimizable queries (SELECT,
  INSERT, UPDATE, DELETE).  Utility commands are still matched on the
  basis of their literal query strings.
   
  There remain some open questions about how to deal with utility statements
  that contain optimizable queries (such as EXPLAIN and SELECT INTO) and how
  to deal with expiring speculative hashtable entries that are made to save
  the normalized form of a query string.  However, fixing these issues should
  require only localized changes, and since there are other open patches
  involving contrib/pg_stat_statements, it seems best to go ahead and commit
  what we've got.
   
  Peter Geoghegan, reviewed by Daniel Farina

Continue reading Waiting for 9.2 – pg_stat_statements improvements