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Peter Geoghegan e5d8a99903 Use full 64-bit XIDs in deleted nbtree pages. ... Otherwise we risk "leaking" deleted pages by making them non-recyclable indefinitely. Commit 6655a729 did the same thing for deleted pages in GiST indexes. That work was used as a starting point here. Stop storing an XID indicating the oldest bpto.xact across all deleted though unrecycled pages in nbtree metapages. There is no longer any reason to care about that condition/the oldest XID. It only ever made sense when wraparound was something _bt_vacuum_needs_cleanup() had to consider. The btm_oldest_btpo_xact metapage field has been repurposed and renamed. It is now btm_last_cleanup_num_delpages, which is used to remember how many non-recycled deleted pages remain from the last VACUUM (in practice its value is usually the precise number of pages that were _newly deleted_ during the specific VACUUM operation that last set the field). The general idea behind storing btm_last_cleanup_num_delpages is to use it to give _some_ consideration to non-recycled deleted pages inside _bt_vacuum_needs_cleanup() -- though never too much. We only really need to avoid leaving a truly excessive number of deleted pages in an unrecycled state forever. We only do this to cover certain narrow cases where no other factor makes VACUUM do a full scan, and yet the index continues to grow (and so actually misses out on recycling existing deleted pages). These metapage changes result in a clear user-visible benefit: We no longer trigger full index scans during VACUUM operations solely due to the presence of only 1 or 2 known deleted (though unrecycled) blocks from a very large index. All that matters now is keeping the costs and benefits in balance over time. Fix an issue that has been around since commit 857f9c36, which added the "skip full scan of index" mechanism (i.e. the _bt_vacuum_needs_cleanup() logic). The accuracy of btm_last_cleanup_num_heap_tuples accidentally hinged upon _when_ the source value gets stored. We now always store btm_last_cleanup_num_heap_tuples in btvacuumcleanup(). This fixes the issue because IndexVacuumInfo.num_heap_tuples (the source field) is expected to accurately indicate the state of the table _after_ the VACUUM completes inside btvacuumcleanup(). A backpatchable fix cannot easily be extracted from this commit. A targeted fix for the issue will follow in a later commit, though that won't happen today. I (pgeoghegan) have chosen to remove any mention of deleted pages in the documentation of the vacuum_cleanup_index_scale_factor GUC/param, since the presence of deleted (though unrecycled) pages is no longer of much concern to users. The vacuum_cleanup_index_scale_factor description in the docs now seems rather unclear in any case, and it should probably be rewritten in the near future. Perhaps some passing mention of page deletion will be added back at the same time. Bump XLOG_PAGE_MAGIC due to nbtree WAL records using full XIDs now. Author: Peter Geoghegan <pg@bowt.ie> Reviewed-By: Masahiko Sawada <sawada.mshk@gmail.com> Discussion: https://postgr.es/m/CAH2-WznpdHvujGUwYZ8sihX=d5u-tRYhi-F4wnV2uN2zHpMUXw@mail.gmail.com		4 years ago
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expected	Use full 64-bit XIDs in deleted nbtree pages.	4 years ago
sql	Disable vacuum page skipping in selected test cases.	5 years ago
.gitignore	pageinspect: Add tests	9 years ago
Makefile	pageinspect: Change block number arguments to bigint	5 years ago
brinfuncs.c	pageinspect: Change block number arguments to bigint	5 years ago
btreefuncs.c	Use full 64-bit XIDs in deleted nbtree pages.	4 years ago
fsmfuncs.c	Update copyright for 2021	5 years ago
ginfuncs.c	Update copyright for 2021	5 years ago
gistfuncs.c	Add "LP_DEAD item?" column to GiST pageinspect functions	4 years ago
hashfuncs.c	pageinspect: Change block number arguments to bigint	5 years ago
heapfuncs.c	Fix some typos, grammar and style in docs and comments	4 years ago
pageinspect--1.0--1.1.sql	Fix typos in some error messages thrown by extension scripts when fed to psql.	11 years ago
pageinspect--1.1--1.2.sql	Fix typos in some error messages thrown by extension scripts when fed to psql.	11 years ago
pageinspect--1.2--1.3.sql	pageinspect/BRIN: minor tweaks	11 years ago
pageinspect--1.3--1.4.sql	Add forgotten file in commit d6061f83a1	10 years ago
pageinspect--1.4--1.5.sql	Update pageinspect extension for parallel query.	9 years ago
pageinspect--1.5--1.6.sql	pageinspect: Add bt_page_items function with bytea argument	8 years ago
pageinspect--1.5.sql	Update pageinspect extension for parallel query.	9 years ago
pageinspect--1.6--1.7.sql	Skip full index scan during cleanup of B-tree indexes when possible	7 years ago
pageinspect--1.7--1.8.sql	pageinspect: Fix types used for bt_metap() columns.	5 years ago
pageinspect--1.8--1.9.sql	Use full 64-bit XIDs in deleted nbtree pages.	4 years ago
pageinspect.control	Add functions to 'pageinspect' to inspect GiST indexes.	5 years ago
pageinspect.h	pageinspect: Change block number arguments to bigint	5 years ago
rawpage.c	Simplify printing of LSNs	4 years ago