On Sat, 2009-05-16 at 23:36 -0400, Jignesh K. Shah wrote:
> Simon Riggs wrote:
> >
> >>> So we can optimize away the scan through the procarray by doing two "if"
> >>> tests, one outside of the lock, one inside. In normal running, both will
> >>> be optimized away, though in read-only periods w
Simon Riggs wrote:
On Thu, 2009-05-14 at 16:21 -0700, Josh Berkus wrote:
So we can optimize away the scan through the procarray by doing two "if"
tests, one outside of the lock, one inside. In normal running, both will
be optimized away, though in read-only periods we would avoid much work
On Thu, 2009-05-14 at 16:21 -0700, Josh Berkus wrote:
> > So we can optimize away the scan through the procarray by doing two "if"
> > tests, one outside of the lock, one inside. In normal running, both will
> > be optimized away, though in read-only periods we would avoid much work.
>
> How muc
Simon,
So we can optimize away the scan through the procarray by doing two "if"
tests, one outside of the lock, one inside. In normal running, both will
be optimized away, though in read-only periods we would avoid much work.
How much work would it be to work up a test patch?
--
Josh Berkus
P
On Thu, 2009-05-14 at 14:06 -0400, Robert Haas wrote:
> Supposing that the patch can be shown to improve performance for
> all-read-only workloads, and supposing further that the patch can be
> shown to have no material negative impact on write-heavy workloads, it
> would also be interesting to t
On Thu, May 14, 2009 at 1:55 PM, Tom Lane wrote:
> Robert Haas writes:
>> On Thu, May 14, 2009 at 1:28 PM, Tom Lane wrote:
>>> GetSnapshotData doesn't take an exclusive lock. Neither does start or
>>> end of a read-only transaction. AFAIK there is no reason, and certainly
>>> no shred of exper
On Thu, 2009-05-14 at 13:28 -0400, Tom Lane wrote:
> Simon Riggs writes:
> > In a thread on -perform it has been observed that our Read-Only
> > scalability is not as good as it could be. One problem being that we
> > need to scan the whole of the ProcArray to derive a snapshot, which
> > becomes
Robert Haas writes:
> On Thu, May 14, 2009 at 1:28 PM, Tom Lane wrote:
>> GetSnapshotData doesn't take an exclusive lock. Neither does start or
>> end of a read-only transaction. AFAIK there is no reason, and certainly
>> no shred of experimental evidence, to think that ProcArrayLock
>> content
On Thu, May 14, 2009 at 1:28 PM, Tom Lane wrote:
> Simon Riggs writes:
>> In a thread on -perform it has been observed that our Read-Only
>> scalability is not as good as it could be. One problem being that we
>> need to scan the whole of the ProcArray to derive a snapshot, which
>> becomes the d
Simon Riggs writes:
> In a thread on -perform it has been observed that our Read-Only
> scalability is not as good as it could be. One problem being that we
> need to scan the whole of the ProcArray to derive a snapshot, which
> becomes the dominant task with many users.
GetSnapshotData doesn't t
In a thread on -perform it has been observed that our Read-Only
scalability is not as good as it could be. One problem being that we
need to scan the whole of the ProcArray to derive a snapshot, which
becomes the dominant task with many users.
If we think about a situation where write transaction
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