From: | Heikki Linnakangas <hlinnakangas(at)vmware(dot)com> |
---|---|
To: | Simon Riggs <simon(at)2ndquadrant(dot)com> |
Cc: | Peter Geoghegan <pg(at)heroku(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>, Andres Freund <andres(at)2ndquadrant(dot)com> |
Subject: | Re: Promise index tuples for UPSERT |
Date: | 2014-10-06 12:25:21 |
Message-ID: | 54328A31.4000501@vmware.com |
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Lists: | pgsql-hackers |
On 10/06/2014 03:21 PM, Heikki Linnakangas wrote:
> On 10/06/2014 03:05 PM, Simon Riggs wrote:
>> My understanding of what you're saying is that if
>>
>> * we have a table with >1 unique index
>> * and we update the values of the uniquely index columns (e.g. PK update)
>> * on both of the uniquely indexed column sets
>> then we get occaisonal deadlocks, just as we would do using current
>> UPDATE/INSERT.
>
> Right. To be precise: you don't need to update both of the columns in
> the same transaction, it's enough that some of the concurrent
> transactions update one column, while other transactions update the
> other column.
Ok, that didn't make much sense. With UPSERT, you have to specify values
for both columns. But it's sufficient that you have a mix of
transactions where only some are UPSERTs, and others are regular UPDATEs
on one of the columns.
- Heikki
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