Re: Re: [WIP] Performance Improvement by reducing WAL for Update Operation

On Thursday, October 04, 2012 8:03 PM Heikki Linnakangas wrote:
On Wednesday, October 03, 2012 9:33 PM Amit Kapila wrote:
On Friday, September 28, 2012 7:03 PM Amit Kapila wrote:
> > On Thursday, September 27, 2012 6:39 PM Amit Kapila wrote:
> > > On Thursday, September 27, 2012 4:12 PM Heikki Linnakangas wrote:
> > > On 25.09.2012 18:27, Amit Kapila wrote:
> > > > If you feel it is must to do the comparison, we can do it in same
> > way
> > > > as we identify for HOT?
> > >
>
>
> > Now I shall do the various tests for following and post it here:
> > a. Attached Patch in the mode where it takes advantage of history
> > tuple b. By changing the logic for modified column calculation to use
> > calculation for memcmp()
>
>

> 1. Please find the results (pgbench_test.htm) for point -2 where there is
> one fixed column updation (last few bytes are random) and second column
> updation is 32 byte random string. The results for 50, 100 are still going
> on others are attached with this mail.

Please find the readings of LZ patch along with Xlog-Scale patch.
The comparison is between for Update operations
base code + Xlog Scale Patch
base code + Xlog Scale Patch + Update WAL Optimization (LZ compression)

The readings have been taken based on below data.
pgbench_xlog_scale_50 -
a. Updated Record size 50, Total Record size 1800
b. Threads 8, 1 ,2
c. Synchronous_commit - off, on

pgbench_xlog_scale_250 -
a. Updated Record size 250, Total Record size 1800
b. Threads 8, 1 ,2
c. Synchronous_commit - off, on

pgbench_xlog_scale_500-
a. Updated Record size 500, Total Record size 1800
b. Threads 8, 1 ,2
c. Synchronous_commit - off, on

Observations
--------------
a. There is still a good performance improvement even if we do Update WAL optimization on top of Xlog Sclaing Patch.
b. There is a slight performance dip for 1 thread (only in Sync mode = off) with Update WAL optimization (LZ compression)
but for 2 threads there is a performance increase.

With Regards,
Amit Kapila.