| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> |
| Cc: | Bruce Momjian <bruce(at)momjian(dot)us>, Marco Nenciarini <marco(dot)nenciarini(at)2ndquadrant(dot)it>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: [RFC] LSN Map |
| Date: | 2015-01-07 15:41:43 |
| Message-ID: | 22402.1420645303@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> writes:
> Bruce Momjian wrote:
>> Have you done any measurements to determine how much backup can be
>> skipped using this method for a typical workload, i.e. how many 16MB
>> page ranges are not modified in a typical span between incremental
>> backups?
> That seems entirely dependent on the specific workload.
Maybe, but it's a reasonable question. The benefit obtained from the
added complexity/overhead clearly goes to zero if you summarize too much,
and it's not at all clear that there's a sweet spot where you win. So
I'd want to see some measurements demonstrating that this is worthwhile.
regards, tom lane
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