Feat: Introduce support for 'pre ping' to detect stale or lost connections #2632
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izeigerman
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| try: | ||
| self._execute(exp.select(exp.Literal.number(1)).sql(dialect=self.dialect)) | ||
| finally: | ||
| self._connection_pool.close_cursor() |
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Why close in all cases? If we just verified the connection is good, why not keep it?
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Is it because we are just validating the connection?
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This is closing a cursor (not connection) to discard the result of the SELECT 1 query which can technically be fetched.
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tobymao
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Really glad to see this PR :) |
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For long running plans, a state connection established at the beginning of a plan application might go stale by the end of it.
This update introduces a "pre-ping" mechanism, ensuring that the connection is not stale before initiating a new transaction. The ping implementation itself is dialect-specific but essentially comes down to executing a
SELECT 1query in all cases except MySQL, which has a first-class API for this purpose.The new behavior is configurable and is turned off by default for all engines except for those likely to be used to store the SQLMesh state: MySQL, MSSQL, and Postgres. This is also only supported for engines with transaction support.