Postgres-XC tutorial PDF - PGCon
Postgres-XC tutorial PDF - PGCon
Postgres-XC tutorial PDF - PGCon
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How single database view is provided<br />
●<br />
Pick up vanilla PostgreSQL MVCC mechanism<br />
●<br />
●<br />
●<br />
Transaction ID (Transaction timestamp)<br />
Snapshot (list if active transactions)<br />
CLOG (whether given transaction is committed)<br />
● Made the former two global → GTM<br />
●<br />
●<br />
●<br />
CLOG is still locally maintained by coordinators and datanodes<br />
Every coordinator/datanode shares the same snapshot at any given time<br />
2PC is used for transactions spanning over multiple coordinators and/or<br />
datanodes<br />
●<br />
Has some performance penalty and may be improved in the future<br />
May 16th, 2012 <strong>Postgres</strong><strong>XC</strong> 18
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