Re: [PoC] Non-volatile WAL buffer - Mailing list pgsql-hackers

From Ashwin Agrawal
Subject Re: [PoC] Non-volatile WAL buffer
Date
Msg-id CAKSySwe2PGgR9R5g8EOxygqEEyaFc9CTALHRts27eVHccMvSsw@mail.gmail.com
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In response to Re: [PoC] Non-volatile WAL buffer  (Tomas Vondra <tomas.vondra@enterprisedb.com>)
Responses Re: [PoC] Non-volatile WAL buffer  (Tomas Vondra <tomas.vondra@enterprisedb.com>)
List pgsql-hackers
On Sun, Nov 22, 2020 at 5:23 PM Tomas Vondra <tomas.vondra@enterprisedb.com> wrote:
I'm not entirely sure whether the "pmemdax" (i.e. unpatched instance
with WAL on PMEM DAX device) is actually safe, but I included it anyway
to see what difference is.

I am curious to learn more on this aspect. Kernels have provided support for "pmemdax" mode so what part is unsafe in stack.

Reading the numbers it seems only at smaller scale modified PostgreSQL is giving enhanced benefit over unmodified PostgreSQL with "pmemdax". For most of other cases the numbers are pretty close between these two setups, so curious to learn, why even modify PostgreSQL if unmodified PostgreSQL can provide similar benefit with just DAX mode.

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