Re: [HACKERS] make async slave to wait for lsn to be replayed

From: Anna Akenteva <a(dot)akenteva(at)postgrespro(dot)ru>
To: Kartyshov Ivan <i(dot)kartyshov(at)postgrespro(dot)ru>
Cc: pgsql-hackers(at)lists(dot)postgresql(dot)org
Subject: Re: [HACKERS] make async slave to wait for lsn to be replayed
Date: 2020-04-07 02:25:53
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On 2020-04-07 00:58, Kartyshov Ivan wrote:
> Ok, here is a new version of patch with single LSN and TIMEOUT.

I had a look at the code and did some more code cleanup, with Ivan's
This is what I did:
- Removed "WAIT FOR" command tag from cmdtaglist.h and renamed WaitStmt
to WaitClause (since there's no standalone WAIT FOR command anymore)
- Added _copyWaitClause() and _equalWaitClause()
- Removed unused #include-s from utility.c
- Adjusted tests and documentation
- Fixed/added some code comments

I have a couple of questions about WaitUtility() though:
- When waiting forever (due to not specifying a timeout), isn't 60
seconds too long of an interval to check for interrupts?
- If we did specify a timeout, it might be a very long one. In this
case, shouldn't we also make sure to wake up sometimes to check for
- Is it OK that specifying timeout = 0 (BEGIN WAIT FOR LSN ... TIMEOUT
0) is the same as not specifying timeout at all?

Anna Akenteva
Postgres Professional:
The Russian Postgres Company

Attachment Content-Type Size
begin_waitfor_v7.patch text/x-diff 26.0 KB

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