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Re: Re: new patch of MERGE (merge_204) & a question about duplicated ctid

From: Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>
To: Stephen Frost <sfrost(at)snowman(dot)net>
Cc: Robert Haas <robertmhaas(at)gmail(dot)com>, Simon Riggs <simon(at)2ndquadrant(dot)com>, Greg Smith <greg(at)2ndquadrant(dot)com>, Marko Tiikkaja <marko(dot)tiikkaja(at)cs(dot)helsinki(dot)fi>, Boxuan Zhai <bxzhai2010(at)gmail(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Re: new patch of MERGE (merge_204) & a question about duplicated ctid
Date: 2011-01-03 15:58:44
Message-ID: 4D21F234.9030707@enterprisedb.com (view raw or flat)
Thread:
Lists: pgsql-hackers
On 03.01.2011 17:56, Stephen Frost wrote:
> * Robert Haas (robertmhaas(at)gmail(dot)com) wrote:
>> Like Heikki, I'd rather have the feature without a workaround for the
>> concurrency issues than no feature.
>
> I'm still trying to figure out the problem with having the table-level
> lock, unless we really think people will be doing concurrent MERGE's
> where they won't overlap..?  I'm also a bit nervous about if the result
> of concurrent MERGE's would actually be correct if we're not taking a
> bigger lock than row-level (I assume we're taking row-level locks as it
> goes through..).
>
> In general, I also thought/expected to have some kind of UPSERT type
> capability with our initial MERGE support, even if it requires a big
> lock and won't operate concurrently, etc.

You can of course LOCK TABLE as a work-around, if that's what you want.

-- 
   Heikki Linnakangas
   EnterpriseDB   http://www.enterprisedb.com

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Subject: Re: Streaming replication as a separate permissions
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