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When executing a MERGE UPDATE action, if there is more than one concurrent update of the target row, the lock-and-retry code would sometimes incorrectly identify the latest version of the target tuple, leading to incorrect results. This was caused by using the ctid field from the TM_FailureData returned by table_tuple_lock() in a case where the result was TM_Ok, which is unsafe because the TM_FailureData struct is not guaranteed to be fully populated in that case. Instead, it should use the tupleid passed to (and updated by) table_tuple_lock(). To reduce the chances of similar errors in the future, improve the commentary for table_tuple_lock() and TM_FailureData to make it clearer that table_tuple_lock() updates the tid passed to it, and most fields of TM_FailureData should not be relied on in non-failure cases. An exception to this is the "traversed" field, which is set in both success and failure cases. Reported-by: Dmitry <dsy.075@yandex.ru> Author: Yugo Nagata <nagata@sraoss.co.jp> Reviewed-by: Dean Rasheed <dean.a.rasheed@gmail.com> Reviewed-by: Chao Li <li.evan.chao@gmail.com> Discussion: https://postgr.es/m/1570d30e-2b95-4239-b9c3-f7bf2f2f8556@yandex.ru Backpatch-through: 15
PostgreSQL tests ================ This directory contains a variety of test infrastructure as well as some of the tests in PostgreSQL. Not all tests are here -- in particular, there are more in individual contrib/ modules and in src/bin. Not all these tests get run by "make check". Check src/test/Makefile to see which tests get run automatically. authentication/ Tests for authentication (but see also below) examples/ Demonstration programs for libpq that double as regression tests via "make check" isolation/ Tests for concurrent behavior at the SQL level kerberos/ Tests for Kerberos/GSSAPI authentication and encryption ldap/ Tests for LDAP-based authentication locale/ Sanity checks for locale data, encodings, etc mb/ Tests for multibyte encoding (UTF-8) support modules/ Extensions used only or mainly for test purposes, generally not suitable for installing in production databases perl/ Infrastructure for Perl-based TAP tests recovery/ Test suite for recovery and replication regress/ PostgreSQL's main regression test suite, pg_regress ssl/ Tests to exercise and verify SSL certificate handling subscription/ Tests for logical replication