Re: Speed up Clog Access by increasing CLOG buffers

On Thu, Mar 17, 2016 at 11:39 AM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
wrote:

I have reviewed the patch.. here are some review comments, I will continue
to review..

1.

+
+ /*
+ * Add the proc to list, if the clog page where we need to update the

+ */
+ if (nextidx != INVALID_PGPROCNO &&
+ ProcGlobal->allProcs[nextidx].clogGroupMemberPage !=
proc->clogGroupMemberPage)
+ return false;

Should we clear all these structure variable what we set above in case we
are not adding our self to group, I can see it will not have any problem
even if we don't clear them,
I think if we don't want to clear we can add some comment mentioning the
same.

+ proc->clogGroupMember = true;
+ proc->clogGroupMemberXid = xid;
+ proc->clogGroupMemberXidStatus = status;
+ proc->clogGroupMemberPage = pageno;
+ proc->clogGroupMemberLsn = lsn;

2.

Here we are updating in our own proc, I think we don't need atomic
operation here, we are not yet added to the list.

+ if (nextidx != INVALID_PGPROCNO &&
+ ProcGlobal->allProcs[nextidx].clogGroupMemberPage !=
proc->clogGroupMemberPage)
+ return false;
+
+ pg_atomic_write_u32(&proc->clogGroupNext, nextidx);

--
Regards,
Dilip Kumar
EnterpriseDB: http://www.enterprisedb.com