On Tue, Aug 2, 2022 at 11:38 AM Tom Lane <tgl@sss.pgh.pa.us> wrote: > I've complained before that the snapshot_too_old TAP tests seem > ridiculously slow --- close to a minute of runtime even on very fast > machines. Today I happened to look closer and realized that there's > an absolutely trivial way to cut that. The core of the slow runtime > is that there's a "pg_sleep(6)" in the test case; which perhaps could > be trimmed, but I'm not on about that right now. What I'm on about > is that two of the three isolation tests allow the isolationtester to > default to running every possible permutation of steps, one of which > doesn't even generate the "snapshot too old" failure. IMV it's > sufficient to run just one permutation. That opinion was shared by > whoever wrote sto_using_hash_index.spec, but they didn't propagate > the idea into the other two tests. > > The attached cuts the test runtime (exclusive of setup) from > approximately 30+24+6 seconds to 6+6+6 seconds, and I don't see > that it loses us one iota of coverage. > > I cleaned up some unused tables and bad comment grammar, too. Yeah, I feel like it was a mistake to allow the list of permutations to be unspecified. It encourages people to just run them all, which is almost never a thoughtful decision. Maybe there's something to be said for running these tests in one successful permutation and one failing permutation -- or maybe even that is overkill -- but running them all seems like a poor idea. -- Robert Haas EDB: http://www.enterprisedb.com