Re: [GENERAL] Database replication... - Mission Critica - Mailing list pgsql-hackers

From Mikheev, Vadim
Subject Re: [GENERAL] Database replication... - Mission Critica
Date
Msg-id 3705826352029646A3E91C53F7189E325186B7@sectorbase2.sectorbase.com
Whole thread Raw
Responses Re: [GENERAL] Database replication... - Mission Critica  (Neil Conway <neilc@samurai.com>)
Re: [GENERAL] Database replication... - Mission Critica  ("Shridhar Daithankar" <shridhar_daithankar@persistent.co.in>)
List pgsql-hackers
> My presumption would be that if you initialize 2 databases to
> a known identical start, have all the same triggers and rules
> on both, then send all queries to both databases, you will
> have 2 identical databases at the end.

This is wrong assumption. If

1st client executes UPDATE t SET a = 1 WHERE b = 2;
2nd client executes UPDATE t SET a = 2 WHERE b = 2;

at "the same time" you don't know in what order these
queries will be executed on two different servers (because
you can't control what transaction will lock record(s)
for update first).

Vadim

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