On Thursday, December 20, 2012 5:46 PM Simon Riggs wrote: > On 13 October 2012 08:54, Amit kapila <amit.kap...@huawei.com> wrote: > > > As per the last discussion for this patch, performance data needs to > be > > provided before this patch's Review can proceed further. > > > > So as per your suggestion and from the discussions about this patch, > I have
> > > > ------------------------------------------------ > > > > 1. There is no performance change for cloumns that have all valid > > values(non- NULLs). > > > > 2. There is a visible performance increase when number of columns > containing > > NULLS are more than > 60~70% in table have large number of columns. > > > > 3. There are visible space savings when number of columns containing > NULLS > > are more than > 60~70% in table have large number of columns. > > > > > > Let me know if there is more performance data needs to be collected > for this > > patch? > > > I can't make sense of your performance report. Because of that I can't > derive the same conclusions from it you do. > > Can you explain the performance results in more detail, so we can see > what they mean? Like which are the patched, which are the unpatched > results? On the extreme let it is mentioned Original Code/ Trim Triling Nulls Patch. In any case I have framed the results again as below: 1. Table with 800 columns A. INSERT tuples with 600 trailing nulls B. UPDATE last column value to "non-null" C. UPDATE last column value to "null" ---------------------+---------------------+--------------------- Original Code | Trim Tailing NULLs | Improvement (%) TPS space used| TPS space used | Results (pages) | (pages) | ---------------------+---------------------+---------------------- 1A: 0.2068 250000 | 0.2302 222223 | 10.1% tps, 11.1% space 1B: 0.0448 500000 | 0.0481 472223 | 6.8% tps, 5.6% space 1C: 0.0433 750000 | 0.0493 694445 | 12.2% tps, 7.4% space 2. Table with 800 columns A. INSERT tuples with 300 trailing nulls B. UPDATE last column value to "non-null" C. UPDATE last column value to "null" ---------------------+---------------------+--------------------- Original Code | Trim Tailing NULLs | Improvement (%) TPS space used| TPS space used | Results (pages) | (pages) | ---------------------+---------------------+---------------------- 2A: 0.0280 666667 | 0.0287 666667 | 2.3% tps, 0% space 2B: 0.0143 1333334 | 0.0152 1333334 | 5.3% tps, 0% space 2C: 0.0145 2000000 | 0.0149 2000000 | 2.9% tps, 0% space 3. Table with 300 columns A. INSERT tuples with 150 trailing nulls B. UPDATE last column value to "non-null" C. UPDATE last column value to "null" ---------------------+---------------------+-------------------- Original Code | Trim Tailing NULLs | Improvement (%) TPS space used| TPS space used | Results (pages) | (pages) | ---------------------+---------------------+-------------------- 3A: 0.2815 166667 | 0.2899 166667 | 2.9% tps, 0% space 3B: 0.0851 333334 | 0.0870 333334 | 2.2% tps, 0% space 3C: 0.0846 500000 | 0.0852 500000 | 0.7% tps, 0% space 4. Table with 300 columns A. INSERT tuples with 250 trailing nulls B. UPDATE last column value to "non-null" C. UPDATE last column value to "null" ---------------------+---------------------+------------------------- Original Code | Trim Tailing NULLs | Improvement (%) TPS space used| TPS space used | Results (pages) | (pages) | ---------------------+---------------------+------------------------- 4A: 0.5447 66667 | 0.5996 58824 | 09.2% tps, 11.8% space 4B: 0.1251 135633 | 0.1232 127790 | -01.5% tps, 5.8% space 4C: 0.1223 202299 | 0.1361 186613 | 10.1% tps, 7.5% space Please let me know, if still it is not clear. With Regards, Amit Kapila. -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers