Simon Riggs <si...@2ndquadrant.com> wrote: > Joachim Wieland <j...@mcknight.de> wrote: >> BEGIN TRANSACTION ISOLATION LEVEL REPEATABLE READ (SNAPSHOT = >> '000003A1-1'); > > I don't see the need to change the BEGIN command, which is SQL > Standard. No, it's not standard. To quote from our docs at: http://www.postgresql.org/docs/9.0/interactive/sql-begin.html#AEN58214 | BEGIN is a PostgreSQL language extension. It is equivalent to the | SQL-standard command START TRANSACTION, whose reference page | contains additional compatibility information. | | Incidentally, the BEGIN key word is used for a different purpose | in embedded SQL. You are advised to be careful about the | transaction semantics when porting database applications. In checking the most recent standards draft I have available, it appears that besides embedded SQL, this keyword is also used in the standard trigger declaration syntax. Using BEGIN to start a transaction is a PostgreSQL extension to the standard. That said, if we support a feature on the nonstandard BEGIN statement, we typically add it as an extension to the standard START TRANSACTION and SET TRANSACTION statements. Through 9.0 that consisted of having a non-standard default for isolation level and the ability to omit commas required by the standard. In 9.1 we added another optional transaction property which defaults to standard behavior: DEFERRABLE. If we're talking about a property of a transaction, like the transaction snapshot, it seems to me to be best to support it using the same statements we use for other transaction properties. -Kevin
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