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As mentioned in the comments in TransactionIdDidAbort() and in heapam_visibility.c, the usual procedure for checking whether a transaction aborted is to first call TransactionIdIsInProgress(), and then !TransactionIdDidCommit(). A couple places didn't get the memo, and used TransactionIdDidAbort() incorrectly. In DoesMultiXactIdConflict(), the consequence was that if a conflicting transaction was just aborting, and had already marked the transaction as aborted in pg_xact, but had not yet removed itself from ProcArray, the function would return false meaning that it does not conflict, even though it was still considered as running by TransactionIdIsInProgress(). That could cause trouble later. One known consequence is that if you then went ahead with updating the row again and called MultiXactIdExpand(), MultiXactIdExpand() would see both the old aborting transaction and the new updater as still running, and throw an ERROR: new multixact has more than one updating member. The multixact-aborted-updater.spec included in this commit exercises that scenario. Another place that got this wrong was in heap_update(), where we check if the updating transaction that was part of a multixid committed or aborted. Because it used TransactionIdDidAbort(), if the updating transaction crashed, it was considered as committed and heap_update() incorrectly returned TM_Updated indicating a conflict, even though the row could be updated. This would only happen if the multixid as whole was still considered running, i.e. if the tuple was still locked by other transactions while the updating transaction crashed. That can happen if the locker is a prepared transaction. The included 060_multixact_crashed_updater.pl test tests that scenario. Author: Chee Wooson <wuqi@vastdata.com.cn> Tested-by: Lionel Hamayon <lionel.hamayon@evolution-digitale.fr> Discussion: https://www.postgresql.org/message-id/5778D6297D3CCF21+202609151836512678486@vastdata.com.cn Backpatch-through: 14
Test extensions and libraries ============================= src/test/modules contains PostgreSQL extensions that are primarily or entirely intended for testing PostgreSQL and/or to serve as example code. The extensions here aren't intended to be installed in a production server and aren't suitable for "real work". Furthermore, while you can do "make install" and "make installcheck" in this directory or its children, it is NOT ADVISABLE to do so with a server containing valuable data. Some of these tests may have undesirable side-effects on roles or other global objects within the tested server. "make installcheck-world" at the top level does not recurse into this directory. Most extensions have their own pg_regress tests or isolationtester specs. Some are also used by tests elsewhere in the tree. If you're adding new hooks or other functionality exposed as C-level API this is where to add the tests for it.