Heikki Linnakangas <heikki.linnakan...@enterprisedb.com> wrote: > On 25.01.2011 05:30, Kevin Grittner wrote: > The readme says this: >> 4. PostgreSQL supports subtransactions -- an issue not mentioned >> in the papers. > > But I don't see any mention anywhere else on how subtransactions > are handled. If a subtransaction aborts, are its predicate locks > immediately released? No. Here's the reasoning. Within a top level transaction, you might start a subtransaction, read some data, and then decide based on what you read that the subtransaction should be rolled back. If the decision as to what is part of the top level transaction can depend on what is read in the subtransaction, predicate locks taken by the subtransaction must survive rollback of the subtransaction. Does that make sense to you? Is there somewhere you would like to see that argument documented? -Kevin
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