Re: Constraint Exclusion and Partition Locking

Ühel kenal päeval, L, 2006-03-04 kell 13:16, kirjutas Rod Taylor:
> Adding a new partition is fairly simple, particularly if you don't care
> about writing RULEs to direct data into it and can rely on a bulk loader
> to figure that part out.
> 
> Removing a partition, on the other hand, is currently impossible to do
> without blocking selects against the table as a whole.
> 
> The reason for this is that when planning to see if a partition needs to
> be read an AccessShareLock is taken and held for the entire transaction.
> 
> If that lock was not there a partition (inherited table) could be
> dropped without any interruptions to normal query processing.
> 
> Is it possible to release the AccessShareLock lock on
> "measurement_yy04mm03" after planning has determined that the structure
> will not be used for this query in a "READ COMMITTED" transaction?
> Serializable obviously would have problems with the partitions
> constraint definition changing.

Ar you sure ? I suspect that the change will not be visible to a
serialisable trx.

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Hannu