On Jan 28, 2008, at 6:14 PM, Simon Riggs wrote:

On Sun, 2008-01-27 at 21:04 -0500, Tom Lane wrote:
[ redirecting thread to -hackers ]

Neil Conway <[EMAIL PROTECTED]> writes:
On Sun, 2008-01-27 at 21:54 +0000, Gregory Stark wrote:
I liked the "synchronized_sequential_scans" idea myself.

I think that's a bit too long. How about "synchronized_scans", or
"synchronized_seqscans"?

We have enable_seqscan already, so that last choice seems to fit in.

If we're going to have a GUC, we may as well make it as useful as
possible.

Currently we set synch scan on when the table is larger than 25% of
shared_buffers. So increasing shared_buffers can actually turn this
feature off.

Rather than having a boolean GUC, we should have a number and make the
parameter "synchronised_scan_threshold". This would then be the size of a table above which we would perform synch scans. If its set to -1, then this would be the same as "off" in all cases. The default value would be
25% of shared_buffers. (Think we can only do that at initdb time
currently).

If we do that, its clearly different from the enable_* parameters, so
the name is easier to decide ;-)


+1
This is in fact a lot more flexible and transparent.
It gives us a lot more control over the process and it is easy to explain / understand.

        best regards,

                hans

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