| From: | Peter Eisentraut <peter_e(at)gmx(dot)net> |
|---|---|
| To: | Simon Riggs <simon(at)2ndQuadrant(dot)com> |
| Cc: | Michael Paquier <michael(dot)paquier(at)gmail(dot)com>, Jeff Janes <jeff(dot)janes(at)gmail(dot)com>, Petr Jelinek <petr(at)2ndquadrant(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>, Jaime Casanova <jaime(at)2ndquadrant(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>, Tomas Vondra <tv(at)fuzzy(dot)cz> |
| Subject: | Re: TABLESAMPLE patch |
| Date: | 2015-04-10 19:19:15 |
| Message-ID: | 55282233.9040903@gmx.net |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
On 4/9/15 7:47 PM, Simon Riggs wrote:
> Having a function-base implementation allows stratified sampling or
> other approaches suited directly to user's data.
How would you implement stratified sampling with this function
interface? You'd need to pass the stratification criteria into the
function somehow. But those would be column names or expressions.
> I don't think its reasonable to force all methods to offer both limits
> on numbers of rows or percentages. They may not be applicable.
Examples?
In a stratified sample I would still ask for X percent from each stratum
or Y rows from each stratum.
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Peter Eisentraut | 2015-04-10 19:26:35 | Re: TABLESAMPLE patch |
| Previous Message | Andres Freund | 2015-04-10 16:03:05 | Re: Replication identifiers, take 4 |