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| author | Peter Geoghegan <pg@bowt.ie> | 2022-03-12 12:52:38 -0800 |
|---|---|---|
| committer | Peter Geoghegan <pg@bowt.ie> | 2022-03-12 12:52:38 -0800 |
| commit | 73f6ec3d3c8d5786c54373e71a096e5acf78e7ca (patch) | |
| tree | bdcfe804efd564ec64a8a14bb8421c4299a54da4 /src/backend/utils/adt/network_spgist.c | |
| parent | 5b68f75e12831cd5b7d8058320c0ca29bbe76067 (diff) | |
| download | postgresql-73f6ec3d3c8d5786c54373e71a096e5acf78e7ca.tar.gz postgresql-73f6ec3d3c8d5786c54373e71a096e5acf78e7ca.zip | |
vacuumlazy.c: document vistest and OldestXmin.
Explain the relationship between vacuumlazy.c's vistest and OldestXmin
cutoffs. These closely related cutoffs are different in subtle but
important ways. Also document a closely related rule: we must establish
rel_pages _after_ OldestXmin to ensure that no XID < OldestXmin can be
missed by lazy_scan_heap().
It's easier to explain these issues by initializing everything together,
so consolidate initialization of vacrel state. Now almost every vacrel
field is initialized by heap_vacuum_rel(). The only remaining exception
is the dead_items array, which is still managed by lazy_scan_heap() due
to interactions with how we initialize parallel VACUUM.
Also move the process that updates pg_class entries for each index into
heap_vacuum_rel(), and adjust related assertions. All pg_class updates
now take place after lazy_scan_heap() returns, which seems clearer.
Author: Peter Geoghegan <pg@bowt.ie>
Reviewed-By: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/20211211045710.ljtuu4gfloh754rs@alap3.anarazel.de
Discussion: https://postgr.es/m/CAH2-WznYsUxVT156rCQ+q=YD4S4=1M37hWvvHLz-H1pwSM8-Ew@mail.gmail.com
Diffstat (limited to 'src/backend/utils/adt/network_spgist.c')
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