Re: Proposal for 9.1: WAL streaming from WAL buffers

On 15/06/10 07:47, Fujii Masao wrote:
> On Tue, Jun 15, 2010 at 12:02 AM, Tom Lane<tgl@sss.pgh.pa.us>  wrote:
>> Fujii Masao<masao.fujii@gmail.com>  writes:
>>> Walsender tries to send WAL up to xlogctl->LogwrtResult.Write. OTOH,
>>> xlogctl->LogwrtResult.Write is updated after XLogWrite() performs fsync.
>>
>> Wrong.  LogwrtResult.Write tracks how far we've written out data,
>> but it is only (known to be) fsync'd as far as LogwrtResult.Flush.
>
> Hmm.. I agree that xlogctl->LogwrtResult.Write indicates the byte position
> we've written. But in the current XLogWrite() code, it's updated after
> XLogWrite() calls issue_xlog_fsync(). No?

issue_xlog_fsync() is only called if the caller requested a flush by 
advancing WriteRqst.Flush.

-- 
   Heikki Linnakangas
   EnterpriseDB   http://www.enterprisedb.com