Rails core - Apr 2009 - expanding the range of fast_string_to_time

Recently, in looking at profiling data from two different  
applications, I found that something like 5% of the application''s time
was being spent in converting strings to times on database fetches.   
Digging in, I found that the "fast" routine for doing this only worked
if there was no timezone in the string.  I ended up monkeypatching  
this in:

  # Rails has a "fast" time parsing shortcut when the database returns
  # a timestamp string without timezone.  Unfortunately, ours does  
return a
  # timezone, but it''s always UTC ("+00").  Hack so we can
use the
  # fast routine still
  module ConnectionAdapters
    class Column
      module Format
        ISO_DATETIME_TZ = /\A(\d{4})-(\d\d)-(\d\d) (\d\d):(\d\d):(\d\d) 
(\.\d+)?(\+\d\d)?\z/
      end

      class << self
        protected
        def fast_string_to_time(string)
          if string =~ Format::ISO_DATETIME_TZ
            tz = $8
            if tz && !(tz == "+00" &&
Base.default_timezone == :utc)
              return nil
            end

            microsec = ($7.to_f * 1_000_000).to_i
            new_time $1.to_i, $2.to_i, $3.to_i, $4.to_i, $5.to_i,  
$6.to_i, microsec
          end
        end
      end
    end
  end


I don''t know how generally applicable this patch would be.  Clearly,  
it only helps if both your DB and your Rails app are configured to run  
in UTC.  We use PostgreSQL, and I don''t know if the same formating is  
used by other databases.  But, I thought I would throw it out for  
comments.


-kevin

> I don''t know how generally applicable this patch would be.
 Clearly,
> it only helps if both your DB and your Rails app are configured to run
> in UTC.  We use PostgreSQL, and I don''t know if the same formating
is
> used by other databases.  But, I thought I would throw it out for
> comments.
This looks like a nice enhancement to the postgresql adapter.  If this
is the only format that postgresql will send back for time with
timezone, then this seems like a great addition. If you create a
lighthouse ticket and attach a patch, people using other versions of
postgresql can verify it makes sense.


-- 
Cheers

Koz