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Re: Future In-Core Replication

From: Jim Nasby <jim(at)nasby(dot)net>
To: Simon Riggs <simon(at)2ndQuadrant(dot)com>
Cc: Hannu Krosing <hannu(at)krosing(dot)net>, Christopher Browne <cbbrowne(at)gmail(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Future In-Core Replication
Date: 2012-05-03 05:58:15
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Lists: pgsql-hackers
On 4/29/12 6:03 AM, Simon Riggs wrote:
>> The DML-WITH-LIMIT-1 is required to do single logical updates on tables
>> >  with non-unique rows.
>> >  And as for any logical updates we will have huge performance problem
>> >  when doing UPDATE or DELETE on large table with no indexes, but
>> >  fortunately this problem is on slave, not master;)
> While that is possible, I would favour the do-nothing approach. By
> making the default replication mode = none, we then require a PK to be
> assigned before allowing replication mode = on for a table. Trying to
> replicate tables without PKs is a problem that can wait basically.

Something that a in-core method might be able to do that an external one can't would be to support a method of uniquely identifying rows in tables with no PK's. A gross example (that undoubtedly wouldn't work in the real world) would be using TID's. A real-world implementation might be based on a hidden serial column.
Jim C. Nasby, Database Architect                   jim(at)nasby(dot)net
512.569.9461 (cell)               

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