What makes this especially dangerous is that in my experience (as a PostgreSQL contributor for 25 years) most users don't test their existing applications against new version in a way that would expose this.Īs for performance, server side prepared statements are said to have little performance impact on simple, single table statements. This is of course in conflict with server side prepared statements as not all clients may have the same statements prepared at the same time or under the same name. When pgbouncer (as one example) is configured in 'transaction' mode, it is allowed to serve many clients through fewer database connection and change the client/dbconnection association on transaction boundaries (i.e. Many users deploy external connection pools like pgbouncer, which allows to connect multiple applications through the same connection pool. That said, this change in behavior should be prominently highlighted in the release notes as it has the potential to break existing installations in a not so obvious way. The default None would enable the automatic choice.īeta Was this translation helpful? Give feedback.Ĭoming here because I am interested in installing 3.1dev0 inside a venv to specifically test this feature (prepared statements). For the control freak, cursor.execute(query, params, prepare=True) would prepare the query immediately, if it isn't already, prepare=False would avoid preparation.Parameters may be fudged on the connection: prepared_threshold=0 would prepare all queries, prepared_threshold=None would disable preparing.if more than connection.prepared_number queries are prepared, the one used least recently is deallocated and evicted from the cache (proposed default: 100).if a query is seen more than connection.prepare_threshold times (proposed default: 5) then it is prepared with the name f'pg3_' and the following executions are prepared.the number of times a query is seen is stored in a LRU cache on the connection.There is an object in psycopg3 that takes care of this transformation it is reduced to bytes, all the client-side manipulations have been done, placeholders have been transformed to $ format). decisions are made after the query is transformed to postgres format (i.e.What I'm thinking about is to prepare queries automatically with a schema such: A cursor.prepare(query) with no args doesn't have types information though: if any it should take an optional array of parameters to get types from. In the past I thought about exposing explicit prepare/deallocate on the cursor, and it was a single prepared query per cursor. Prepared statements in the server are per session, so any form of cache is better connected to the connection than the cursor, although the cursors are the obvious interface to give commands. ![]()
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