On 3/27/2011 6:21 PM, Robert Haas wrote:
On Sun, Mar 27, 2011 at 3:25 PM, Jan Wieck<janwi...@yahoo.com>  wrote:
 Since we are talking about stable releases, I think just releasing and
 reacquiring the exclusive lock is enough. We can then try to further improve
 things for future releases.

That seems unsafe - things can change under you while you don't hold the lock...

The only change relevant in this case would be some concurrent client extending the relation while we don't hold the lock. A call to RelationGetNumberOfBlocks() after reacquiring the lock will tell. Safety reestablished.

I kind of like the idea of committing the transaction and then
beginning a new one just to do the truncation.  Given the way the
deadlock detector treats autovacuum, the current coding seems quite
risky.

I don't like a 1,000 ms hiccup in my system, regardless of how many transaction hoops you make it go through.


Jan

--
Anyone who trades liberty for security deserves neither
liberty nor security. -- Benjamin Franklin

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