PostgreSQL 是什麼，跟 MySQL 有什麼差別

What's new in this version:

- Fix failure to remove non-first segments of large tables
- PostgreSQL splits large tables into multiple files (normally with 1GB per file). The logic for dropping a table was broken and would miss removing all but the first such file, in two cases: drops of temporary tables and WAL replay of drops of regular tables. Applications that routinely create multi-gigabyte temporary tables could suffer significant disk space leakage.
- Orphaned temporary-table files are removed during postmaster start, so the mere act of updating to 15.1 is sufficient to clear any leaked temporary-table storage. However, if you suffered any database crashes while using 15.0, and there might have been large tables dropped just before such crashes, it's advisable to check the database directories for files named according to the pattern NNNN.NN. If there is no matching file named just NNNN (without the .NN suffix), these files should be removed manually.
- Fix handling of DEFAULT tokens that appear in a multi-row VALUES clause of an INSERT on an updatable view
- This oversight could lead to “cache lookup failed for type” errors, or in older branches even to crashes.
- Disallow rules named _RETURN that are not ON SELECT
- This avoids confusion between a view's ON SELECT rule and any other rules it may have.
- Avoid failure in EXPLAIN VERBOSE for a query using SEARCH BREADTH FIRST with constant initial values
- Prevent use of MERGE on a partitioned table with foreign-table partitions
- The case isn't supported, and previously threw an incomprehensible error.
- Fix construction of per-partition foreign key constraints while doing ALTER TABLE ATTACH PARTITION
- Previously, incorrect or duplicate constraints could be constructed for the newly-added partition.
- Fix planner failure with extended statistics on partitioned or inherited tables
- Some cases failed with “cache lookup failed for statistics object”
- Fix mis-ordering of WAL operations in fast insert path for GIN indexes
- This mistake is not known to have any negative consequences within core PostgreSQL, but it did cause issues for some extensions
- Fix bugs in logical decoding when replay starts from a point between the beginning of a transaction and the beginning of its subtransaction
- These errors could lead to assertion failures in debug builds, and otherwise to memory leaks
- Accept interrupts in more places during logical decoding
- This ameliorates problems with slow shutdown of replication workers
- Prevent attempts to replicate into a foreign-table partition in replication workers
- Although partitioned tables can have foreign tables as partitions, replicating into such a partition isn't currently supported. The logical replication worker process would crash if it was attempted. Now, an error is thrown.
- Avoid crash after function syntax error in replication workers
- If a syntax error occurred in a SQL-language or PL/pgSQL-language CREATE FUNCTION or DO command executed in a logical replication worker, the worker process would crash with a null pointer dereference or assertion failure
- Avoid double call of the shutdown callback of an archiver module
- Add plan-time check for attempted access to a table that has no table access method
- This prevents a crash in some catalog-corruption scenarios, for example use of a view whose ON SELECT rule is missing
- Prevent postmaster crash when shared-memory state is corrupted
- The postmaster process is supposed to survive and initiate a database restart if shared memory becomes corrupted, but one bit of code was being insufficiently cautious about that
- In libpq, handle single-row mode correctly when pipelining
- The single-row flag was not reset at the correct time if pipeline mode was also active
- Fix psql's exit status when a command-line query is canceled
- psql -c query would exit successfully if the query was canceled. Fix it to exit with nonzero status, as in other error cases
- Allow cross-platform tablespace relocation in pg_basebackup
- Allow the remote path in --tablespace-mapping to be either a Unix-style or Windows-style absolute path, since the source server could be on a different OS than the local system.
- Fix pg_dump's failure to dump comments attached to some CHECK constraints
- Fix CREATE DATABASE to allow its oid parameter to exceed 231
- This oversight prevented pg_upgrade from succeeding when the source installation contained databases with OIDs larger than that
- In pg_stat_statements, fix access to already-freed memory
- This occurred if pg_stat_statements tracked a ROLLBACK command issued via extended query protocol. In debug builds it consistently led to an assertion failure. In production builds there would often be no visible ill effect; but if the freed memory had already been reused, the likely result would be to store garbage for the query string.
- Fix incompatibilities with LLVM 15
- Allow use of __sync_lock_test_and_set() for spinlocks on any machine
- This eases porting to new machine architectures, at least if you're using a compiler that supports this GCC builtin function
- Rename symbol REF to REF_P to avoid compile failure on recent macOS
- Avoid using sprintf, to avoid compile-time deprecation warnings
- Update time zone data files to tzdata release 2022f for DST law changes in Chile, Fiji, Iran, Jordan, Mexico, Palestine, and Syria, plus historical corrections for Chile, Crimea, Iran, and Mexico.
- Also, the Europe/Kiev zone has been renamed to Europe/Kyiv. Also, the following zones have been merged into nearby, more-populous zones whose clocks have agreed with them since 1970: Antarctica/Vostok, Asia/Brunei, Asia/Kuala_Lumpur, Atlantic/Reykjavik, Europe/Amsterdam, Europe/Copenhagen, Europe/Luxembourg, Europe/Monaco, Europe/Oslo, Europe/Stockholm, Indian/Christmas, Indian/Cocos, Indian/Kerguelen, Indian/Mahe, Indian/Reunion, Pacific/Chuuk, Pacific/Funafuti, Pacific/Majuro, Pacific/Pohnpei, Pacific/Wake and Pacific/Wallis. (This indirectly affects zones that were already links to one of these: Arctic/Longyearbyen, Atlantic/Jan_Mayen, Iceland, Pacific/Ponape, Pacific/Truk, and Pacific/Yap.) America/Nipigon, America/Rainy_River, America/Thunder_Bay, Europe/Uzhgorod, and Europe/Zaporozhye were also merged into nearby zones after discovering that their claimed post-1970 differences from those zones seem to have been errors. In all these cases, the previous zone name remains as an alias; but the actual data is that of the zone that was merged into.
- These zone mergers result in loss of pre-1970 timezone history for the merged zones, which may be troublesome for applications expecting consistency of timestamptz display. As an example, the stored value 1944-06-01 12:00 UTC would previously display as 1944-06-01 13:00:00+01 if the Europe/Stockholm zone is selected, but now it will read out as 1944-06-01 14:00:00+02.
- It is possible to build the time zone data files with options that will restore the older zone data, but that choice also inserts a lot of other old (and typically poorly-attested) zone data, resulting in more total changes from the previous release than accepting these upstream changes does. PostgreSQL has chosen to ship the tzdb data as-recommended, and so far as we are aware most major operating system distributions are doing likewise. However, if these changes cause significant problems for your application, a possible solution is to install a local build of the time zone data files using tzdb's backwards-compatibility options (see their PACKRATDATA and PACKRATLIST options).