| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> | 
|---|---|
| To: | Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com> | 
| Cc: | Fujii Masao <masao(dot)fujii(at)gmail(dot)com>, pgsql-hackers(at)postgreSQL(dot)org | 
| Subject: | Re: "caught_up" status in walsender | 
| Date: | 2010-06-02 19:21:36 | 
| Message-ID: | 10535.1275506496@sss.pgh.pa.us | 
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Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com> writes:
> On 02/06/10 21:44, Tom Lane wrote:
>> In the current coding, the effect of not setting *caughtup here is just
>> that we uselessly call XLogSend an extra time for each transmission
>> (because the main loop won't ever delay immediately after a
>> transmission).  But without this, we'd never send caughtup = true
>> to the slave.
> That's intentional. It could take some time for the WAL to be sent, if 
> the network is busy, so by the time XLogSend returns you might well not 
> be caught up anymore.
It may have been intentional, but it's still wrong.  If you were able to
pull all of WAL into the record-to-be-sent, you should sleep afterwards,
not send an extra record containing a few more bytes.
regards, tom lane
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