| From: | Peter Geoghegan <pg(at)bowt(dot)ie> |
|---|---|
| To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
| Cc: | Kevin Grittner <kgrittn(at)gmail(dot)com>, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, Alik Khilazhev <a(dot)khilazhev(at)postgrespro(dot)ru>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>, Sokolov Yura <y(dot)sokolov(at)postgrespro(dot)ru> |
| Subject: | Re: LP_DEAD hinting and not holding on to a buffer pin on leaf page (Was: [WIP] Zipfian distribution in pgbench) |
| Date: | 2017-08-05 19:20:41 |
| Message-ID: | CAH2-Wz=pfZ3OM8X2jLQf3mJOJYUN2x04jL5SLEHd0YKMuyAt5g@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Fri, Aug 4, 2017 at 3:30 PM, Peter Geoghegan <pg(at)bowt(dot)ie> wrote:
> Yura Sokolov of Postgres Pro performed this benchmark at my request.
> He took the 9.5 commit immediately proceeding 2ed5b87f9 as a baseline.
I attach a simple patch that comments out the release of the buffer
pin for logged tables where an MVCC snapshot is used for a scan that
is not an index-only scan. This is the simplest way of evaluating the
effects of disabling 2ed5b87f9. Yura or others may find this helpful.
To be clear, I am certainly not suggesting that we should revert
2ed5b87f9. I do think that we need to give serious thought to fixing
the regression that 2ed5b87f9 introduced for LP_DEAD setting by index
scans, though.
--
Peter Geoghegan
| Attachment | Content-Type | Size |
|---|---|---|
| disable-release-leaf-pin.patch | text/x-patch | 651 bytes |
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