On 17/08/2018 06:47, Andrey Lepikhov wrote:
I propose the patch for fix one small code defect.
The XLogReadRecord() function reads the pages of a WAL segment that
contain a WAL-record. Then it creates a readRecordBuf buffer in private
memory of a backend and copy record from the pages to the readRecordBuf
buffer. Pointer 'record' is set to the beginning of the readRecordBuf
buffer.
But if the WAL-record is fully placed on one page, the XLogReadRecord()
function forgets to bind the "record" pointer with the beginning of the
readRecordBuf buffer. In this case, XLogReadRecord() returns a pointer
to an internal xlog page. This patch fixes the defect.
Hmm. I agree it looks weird the way it is. But I wonder, why do we even
copy the record to readRecordBuf, if it fits on the WAL page? Returning
a pointer to the xlog page buffer seems OK in that case. What if we
remove the memcpy(), instead?
- Heikki
