| From: | Jim Nasby <Jim(dot)Nasby(at)BlueTreble(dot)com> |
|---|---|
| To: | Andres Freund <andres(at)anarazel(dot)de>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Andreas Karlsson <andreas(at)proxel(dot)se>, Julien Tachoires <julmon(at)gmail(dot)com>, Alex Shulgin <ash(at)commandprompt(dot)com>, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, Jaime Casanova <jaime(at)2ndquadrant(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: patch : Allow toast tables to be moved to a different tablespace |
| Date: | 2015-07-14 21:57:34 |
| Message-ID: | 55A585CE.306@BlueTreble.com |
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| Lists: | pgsql-hackers |
On 7/7/15 7:07 AM, Andres Freund wrote:
> On 2015-07-03 18:03:58 -0400, Tom Lane wrote:
>> I have just looked through this thread, and TBH I think we should reject
>> this patch altogether --- not RWF, but "no we don't want this". The
>> use-case remains hypothetical: no performance numbers showing a real-world
>> benefit have been exhibited AFAICS.
>
> It's not that hard to imagine a performance benefit though? If the
> toasted column is accessed infrequently/just after filtering on other
> columns (not uncommon) it could very well be beneficial to put the main
> table on fast storage (SSD) and the toast table on slow storage
> (spinning rust).
>
> I've seen humoungous toast tables that are barely ever read for tables
> that are constantly a couple times in the field.
+1. I know of one case where the heap was ~8GB and TOAST was over 400GB.
--
Jim Nasby, Data Architect, Blue Treble Consulting, Austin TX
Data in Trouble? Get it in Treble! http://BlueTreble.com
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