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Intel Mac OS X 10.13; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20180926155443.u4zh7jactzflys3z@alvherre.pgsql> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit List-Id: List-Help: List-Subscribe: List-Post: List-Owner: List-Archive: Precedence: bulk On 26/09/2018 17:54, Alvaro Herrera wrote: > What could be the use for the transaction timestamp? I think one of the > most important uses (at least in pg_stat_activity) is to verify that > transactions are not taking excessively long time to complete; that's > known to cause all sorts of trouble in Postgres, and probably other > DBMSs too. If we don't accurately measure what it really is, and > instead keep the compatibility behavior, we risk panicking people > because they think some transaction has been running for a long time > when in reality it's just a very long procedure which commits frequently > enough not to be a problem. That's certainly a good argument. Note that if we implemented that the transaction timestamp is advanced inside procedures, that would also mean that the transaction timestamp as observed in pg_stat_activity would move during VACUUM, for example. That might or might not be desirable. -- Peter Eisentraut http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services