On 9/15/15 11:04 PM, Fujii Masao wrote:
> If --slot option is specified, pg_receivexlog reports a flush position to
> the server even though --synchronous is not specified. So users might think
> that --synchrnous option is not necessary for synchronous pg_receivexlog
> setting. But that's not true. If --synchronous option is not specified, the
> received WAL data is flushed to the disk only when WAL segment is switched.
> So the transactions on the master need to wait for a long time, i.e.,
> we can think that synchronous pg_receivexlog doesn't work smoothly.
> To avoid such situation, --synchronous option also needs to be specified and
> which makes pg_receivexlog flush WAL data immediately after receiving it.
Thank you for this information. I hope to have clarified this in the
documentation now.
