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
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