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Thread: CLUSTER locking

CLUSTER locking

From
Christopher Kings-Lynne
Date:
Hi,

Is there a way the CLUSTER command can be changed to not take an 
exclusive lock on the table, and instead allow reads on the old table 
and index, just preventing writes?

Chris

Re: CLUSTER locking

From
Tom Lane
Date:
Christopher Kings-Lynne <chriskl@familyhealth.com.au> writes:
> Is there a way the CLUSTER command can be changed to not take an 
> exclusive lock on the table,

No.  Committing the relfilenode swap would cut the knees off of any
active scan on the old file.
        regards, tom lane

Re: CLUSTER locking

From
Christopher Kings-Lynne
Date:
> No.  Committing the relfilenode swap would cut the knees off of any
> active scan on the old file.

Could it upgrade its lock to exclusive just before doing the swap?

Chris

Re: CLUSTER locking

From
Tom Lane
Date:
Christopher Kings-Lynne <chriskl@familyhealth.com.au> writes:
>> No.  Committing the relfilenode swap would cut the knees off of any
>> active scan on the old file.

> Could it upgrade its lock to exclusive just before doing the swap?

That is a recipe for deadlock failures.
        regards, tom lane