From: | Fujii Masao <masao(dot)fujii(at)gmail(dot)com> |
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To: | Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp> |
Cc: | Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com>, Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com>, Michael Paquier <michael(dot)paquier(at)gmail(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Thom Brown <thom(at)linux(dot)com>, Beena Emerson <memissemerson(at)gmail(dot)com>, Josh Berkus <josh(at)agliodbs(dot)com>, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Support for N synchronous standby servers - take 2 |
Date: | 2016-03-22 14:08:36 |
Message-ID: | CAHGQGwFYG829=2r4mxV0ULeBNaUuG0ek_10yymx8Cu-gLYcLng@mail.gmail.com |
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On Tue, Mar 22, 2016 at 9:58 PM, Kyotaro HORIGUCHI
<horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp> wrote:
> Thank you for the revised patch.
Thanks for reviewing the patch!
> This version looks to focus on n-priority method. Stuffs for the
> other methods like n-quorum has been removed. It is okay for me.
I don't think it's so difficult to extend this version so that
it supports also quorum commit.
> StringInfo for double-quoted names seems to me to be overkill,
> since it allocates 1024 byte block for every such name. A static
> buffer seems enough for the usage as I said.
So, what about changing the scanner code as follows?
<xd>{xdstop} {
yylval.str = pstrdup(xdbuf.data);
pfree(xdbuf.data);
BEGIN(INITIAL);
return NAME;
> The parser is called for not only for SIGHUP, but also for
> starting of every walsender. The latter is not necessary but it
> is the matter of trade-off between simplisity and
> effectiveness.
Could you elaborate why you think that's not necessary?
BTW, in previous patch, s_s_names is parsed by postmaster during the server
startup. A child process takes over the internal data struct for the parsed
s_s_names when it's forked by the postmaster. This is what the previous
patch was expecting. However, this doesn't work in EXEC_BACKEND environment.
In that environment, the data struct should be passed to a child process via
the special file (like write_nondefault_variables() does), or it should
be constructed during walsender startup (like latest version of the patch
does). IMO the latter is simpler.
Regards,
--
Fujii Masao
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