On Jan 28, 2008 3:56 PM, Vlad <marchenko@xxxxxxxxx> wrote:
> Hello,
>
> 1. Freshly imported DB size on disk was about 3% smaller for 8.3
> 2. We ran several tests and found 8.3 generally 10% slower than 8.2.6.
> We took special measures to make sure that no third factors involved
> (no other apps running, all data was cached from disks, etc). Below
> is one of the queries that we used for testing (I anonymized table
> names) along with query plan for both 8.3 and 8.2. The query execution
> plans are the same for both versions, but what we found quite
> interesting is that if we add all the times from each line of 8.2's
> query plan, it roughly adds-up to the total execution time. For 8.3's
> plan each line shows a shorter time, yet resulting in longer total
> runtime. Also, summing 8.3's plan lines doesn't come close to the
> total execution time:
This last bit often means there's some overhead in the systems
timeofday() function calls.
If you just use \timing from psql, and run the script without explain
analyze, what speeds do you get on each?
---------------------------(end of broadcast)---------------------------
TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match
