| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> |
| Cc: | Pavan Deolasee <pavan(dot)deolasee(at)gmail(dot)com>, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, Bruce Momjian <bruce(at)momjian(dot)us>, Jaime Casanova <jaime(dot)casanova(at)2ndquadrant(dot)com>, Haribabu Kommi <kommi(dot)haribabu(at)gmail(dot)com>, Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Patch: Write Amplification Reduction Method (WARM) |
| Date: | 2017-03-30 14:25:26 |
| Message-ID: | CA+TgmoYfQeBXzXZ6wzJxLb8f01im4YAG216Doav+fAJ130rPwA@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Thu, Mar 30, 2017 at 10:08 AM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> I think we should not consider doing compression and decompression as
> free at this point in code, because we hold a buffer lock during
> recheck. Buffer locks are meant for short-term locks (it is even
> mentioned in storage/buffer/README), doing all the
> compression/decompression/detoast stuff under these locks doesn't
> sound advisable to me. It can block many concurrent operations.
Compression and decompression might cause performance problems, but
try to access the TOAST table would be fatal; that probably would have
deadlock hazards among other problems.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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