Re: refresh materialized view concurrently

Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Robert Haas <robertmhaas@gmail.com> writes:
>> Tom Lane <tgl@sss.pgh.pa.us> wrote:
>>> Are we somehow not going through ExecOpenIndices?
>
>> I dunno.  I just did a quick black-box test:
>>
>> [ begin; insert; without commit ]
>>
>> No foo_pkey anywhere.
>
> That proves nothing, as we don't keep such locks after the query
> (and there's no reason to AFAICS).  See ExecCloseIndices.

OK.  I had seen that no locks were held after the insert and wasn't
aware that we acquired and then released them for each insert
within a transaction.  On the other hand, we acquire locks on all
indexes even for a HOT UPDATE which uses a seqscan, and hold those
until end of transaction.  Is there a reason for that?

I suppose that since a concurrent refresh is very likely to lock
all these indexes with RowExclusiveLock anyway, as a result of the
DELETE, UPDATE and INSERT statements subsequently issued through
SPI, I might was well acquire that lock when I look at the
definition, and not release it -- so that the subsequent locks are
local to the backend, and therefore faster.

--
Kevin Grittner
EnterpriseDB: http://www.enterprisedb.com
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