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ecpglib has been calling it once per SQL query and once per EXEC SQL GET DESCRIPTOR. Instead, if newlocale() has not succeeded before, call it while establishing a connection. This mitigates three problems: - If newlocale() failed in EXEC SQL GET DESCRIPTOR, the command silently proceeded without the intended locale change. - On AIX, each newlocale()+freelocale() cycle leaked memory. - newlocale() CPU usage may have been nontrivial. Fail the connection attempt if newlocale() fails. Rearrange ecpg_do_prologue() to validate the connection before its uselocale(). The sort of program that may regress is one running in an environment where newlocale() fails. If that program establishes connections without running SQL statements, it will stop working in response to this change. I'm betting against the importance of such an ECPG use case. Most SQL execution (any using ECPGdo()) has long required newlocale() success, so there's little a connection could do without newlocale(). Back-patch to v10 (all supported versions). Reviewed by Tom Lane. Reported by Guillaume Lelarge. Discussion: https://postgr.es/m/20220101074055.GA54621@rfd.leadboat.com
src/interfaces/ecpg/README.dynSQL descriptor statements have the following shortcomings - input descriptors (USING DESCRIPTOR <name>) are not supported Reason: to fully support dynamic SQL the frontend/backend communication should change to recognize input parameters. Since this is not likely to happen in the near future and you can cover the same functionality with the existing infrastructure (using s[n]printf), I'll leave the work to someone else.