Re: [HACKERS] Add min and max execute statement time in pg_stat_statement

Interesting patch. I did a quick review looking only into the patch file. The "sum of variances" variable contains the "sum of squared differences" instead, I think. And a very minor aspect: The term "standard deviation" in your code stands for (corrected) sample standard deviation, I think, beca

Re: [HACKERS] Add min and max execute statement time in pg_stat_statement

Andrew Dunstan schrieb am 2015-01-20: > On 01/20/2015 01:26 PM, Arne Scheffer wrote: > >Interesting patch. > >I did a quick review looking only into the patch file. > >The "sum of variances" variable contains > >the "sum of squared differences" in

Re: [HACKERS] Add min and max execute statement time in pg_stat_statement

> >>I don't understand. I'm following pretty exactly the calculations > >>stated > >>at ; > >>I'm not a statistician. Perhaps others who are more literate in Maybe I'm mistaken here, but I think, the algorithm is not that complicated. I try to ex

Re: [HACKERS] Add min and max execute statement time in pg_stat_statement

David G Johnston schrieb am 2015-01-21: > Andrew Dunstan wrote > > On 01/20/2015 01:26 PM, Arne Scheffer wrote: > >> And a very minor aspect: > >> The term "standard deviation" in your code stands for > >> (corrected) sample standard deviation, I th

Re: [HACKERS] Add min and max execute statement time in pg_stat_statement

Sorry, corrected second try because of copy&paste mistakes: VlG-Arne > Comments appreciated. > Definition var_samp = Sum of squared differences /n-1 > Definition stddev_samp = sqrt(var_samp) > Example N=4 > 1.) Sum of squared differences > 1_4Sum(Xi-XM4)² > = > 2.) adding nothing > 1_4Sum(X

Re: [HACKERS] Add min and max execute statement time in pg_stat_statement

On Wed, 21 Jan 2015, Andrew Dunstan wrote: On 01/21/2015 09:27 AM, Arne Scheffer wrote: Sorry, corrected second try because of copy&paste mistakes: VlG-Arne Comments appreciated. Definition var_samp = Sum of squared differences /n-1 Definition stddev_samp = sqrt(var_samp) Example N

Re: [HACKERS] Add min and max execute statement time in pg_stat_statement

Andrew Dunstan schrieb am 2015-01-21: > On 01/21/2015 11:21 AM, Arne Scheffer wrote: > >Why is it a bad thing to call the column "stddev_samp" analog to the > >aggregate function or make a note in the documentation, that the > >sample stddev is used to comput

Re: [HACKERS] [PATCH] explain sortorder

without looking that that was what it did already, >else I'd have complained too. > regards, tom lane We will change the patch according to Heikkis suggestions. A nice Christmas & all the best in the New Year Arne Scheffer http://www.uni-muenster.de/ZIV/M

Re: [HACKERS] [PATCH] explain sortorder

Hi, we will also remove the following is lc_collate hint in the next version, showing only mandatory info as suggested. /* for those who use COLLATE although their default is already the wanted */ if (strcmp(collname, localeptr) == 0) {