Re: Hash Indexes

On Thu, Sep 29, 2016 at 8:27 PM, Amit Kapila <amit.kapila16@gmail.com> wrote:
> On Thu, Sep 29, 2016 at 6:04 AM, Robert Haas <robertmhaas@gmail.com> wrote:
>
>> Another thing I don't quite understand about this algorithm is that in
>> order to conditionally lock the target primary bucket page, we'd first
>> need to read and pin it.  And that doesn't seem like a good thing to
>> do while we're holding a shared content lock on the metapage, because
>> of the principle that we don't want to hold content locks across I/O.
>>
>

Aren't we already doing this during BufferAlloc() when the buffer
selected by StrategyGetBuffer() is dirty?

> I think we can release metapage content lock before reading the buffer.
>

On thinking about this again, if we release the metapage content lock
before reading and pinning the primary bucket page, then we need to
take it again to verify if the split has happened during the time we
don't have a lock on a metapage.  Releasing and again taking content
lock on metapage is not
good from the performance aspect.  Do you have some other idea for this?

-- 
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com