c431986de1
Despite the best efforts of commit 0e5c82380, we're still seeing occasional failures of postgres_fdw's query_cancel test in the buildfarm. Investigation suggests that its 100ms timeout is still not enough to reliably ensure that the remote side starts the query before receiving the cancel request --- and if it hasn't, it will just discard the request because it's idle. We discussed allowing a cancel request to kill the next-received query, but that would have wide and perhaps unpleasant side-effects. What seems safer is to make postgres_fdw do what a human user would likely do, which is issue another cancel request if the first one didn't seem to do anything. We'll keep the same overall 30 second grace period before concluding things are broken, but issue additional cancel requests after 1 second, then 2 more seconds, then 4, then 8. (The next one in series is 16 seconds, but we'll hit the 30 second timeout before that.) Having done that, revert the timeout in query_cancel.sql to 10 ms. That will still be enough on most machines, most of the time, for the remote query to start; but now we're intentionally risking the race condition occurring sometimes in the buildfarm, so that the repeat-cancel code path will get some testing. As before, back-patch to v17. We might eventually contemplate back-patching this further, and/or adding similar logic to dblink. But given the lack of field complaints to date, this feels like mostly an exercise in test case stabilization, so v17 is enough. Discussion: https://postgr.es/m/colnv3lzzmc53iu5qoawynr6qq7etn47lmggqr65ddtpjliq5d@glkveb4m6nop
PostgreSQL Database Management System
This directory contains the source code distribution of the PostgreSQL database management system.
PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings.
Copyright and license information can be found in the file COPYRIGHT.
General documentation about this version of PostgreSQL can be found at https://www.postgresql.org/docs/devel/. In particular, information about building PostgreSQL from the source code can be found at https://www.postgresql.org/docs/devel/installation.html.
The latest version of this software, and related software, may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.