On 21.03.2018 10:08, Konstantin Knizhnik wrote:
On 21.03.2018 04:50, Peter Eisentraut wrote:
On 3/16/18 12:08, Konstantin Knizhnik wrote:
pq_putmessage_noblock copies data from ctx->out buffer to libpq
buffers.
After it we write timestamp to ctx->out buffer.
And comments says that we should do it "as late as possible".
But this timestamp is not included in the copy data packet which is
already copied to libpq connection buffer.
There is a pq_flush_if_writable() right after this that will write out
the rest of ctx->out.
Sorry, But PQ_flush_if_writable calls socket_flush_if_writable (or
mq_flush_if_writable).
This function flushes pqlib connection buffer, i.e. PqSendBuffer.
This buffer has no relation to ctx->out_buffer, where timestamp is
written.
The obvious fix is to move assignment of timestamp prior to
pq_putmessage_noblock:
WalSndWriteData(LogicalDecodingContext *ctx, XLogRecPtr lsn,
TransactionId xid,
bool last_write)
{
TimestampTz now;
/*
* Fill the send timestamp last, so that it is taken as late as
possible.
* This is somewhat ugly, but the protocol is set as it's already
used for
* several releases by streaming physical replication.
*/
resetStringInfo(&tmpbuf);
now = GetCurrentTimestamp();
pq_sendint64(&tmpbuf, now);
memcpy(&ctx->out->data[1 + sizeof(int64) + sizeof(int64)],
tmpbuf.data, sizeof(int64));
/* output previously gathered data in a CopyData packet */
pq_putmessage_noblock('d', ctx->out->data, ctx->out->len);
Sorry, I have not received confirmation whether it is a bug or not and
is it going to be fixed.
--
Konstantin Knizhnik
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company
