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Revert "Add eager and lazy freezing strategies to VACUUM."

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This reverts commit 4d41799261.  Broad
concerns about regressions caused by eager freezing strategy have been
raised.  Whether or not these concerns can be worked through in any time
frame is far from certain.

Discussion: https://postgr.es/m/20230126004347.gepcmyenk2csxrri@awork3.anarazel.de
This commit is contained in:
Peter Geoghegan
2023-01-25 22:22:27 -08:00
parent 8b5f36bb6c
commit 6c6b497266
12 changed files with 14 additions and 197 deletions
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43
src/backend/access/heap/vacuumlazy.c
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@ -153,8 +153,6 @@ typedef struct LVRelState
bool aggressive;
/* Use visibility map to skip? (disabled by DISABLE_PAGE_SKIPPING) */
bool skipwithvm;
/* Eagerly freeze pages that are eligible to become all-frozen? */
bool eager_freeze_strategy;
/* Wraparound failsafe has been triggered? */
bool failsafe_active;
/* Consider index vacuuming bypass optimization? */
@ -245,7 +243,6 @@ typedef struct LVSavedErrInfo
/* non-export function prototypes */
static void lazy_scan_heap(LVRelState *vacrel);
static void lazy_scan_strategy(LVRelState *vacrel);
static BlockNumber lazy_scan_skip(LVRelState *vacrel, Buffer *vmbuffer,
BlockNumber next_block,
bool *next_unskippable_allvis,
@ -475,10 +472,6 @@ heap_vacuum_rel(Relation rel, VacuumParams *params,
vacrel->skipwithvm = skipwithvm;
/*
* Now determine VACUUM's freezing strategy
*/
lazy_scan_strategy(vacrel);
if (verbose)
{
if (vacrel->aggressive)
@ -1274,38 +1267,6 @@ lazy_scan_heap(LVRelState *vacrel)
lazy_cleanup_all_indexes(vacrel);
}
/*
* lazy_scan_strategy() -- Determine freezing strategy.
*
* Our lazy freezing strategy is useful when putting off the work of freezing
* totally avoids freezing that turns out to have been wasted effort later on.
* Our eager freezing strategy is useful with larger tables that experience
* continual growth, where freezing pages proactively is needed just to avoid
* falling behind on freezing (eagerness is also likely to be cheaper in the
* short/medium term for such tables, but the long term picture matters most).
*/
static void
lazy_scan_strategy(LVRelState *vacrel)
{
BlockNumber rel_pages = vacrel->rel_pages;
/*
* Decide freezing strategy.
*
* The eager freezing strategy is used whenever rel_pages exceeds a
* threshold controlled by the freeze_strategy_threshold GUC/reloption.
*
* Also freeze eagerly with an unlogged or temp table, where the total
* cost of freezing pages is mostly just the cycles needed to prepare a
* set of freeze plans. Executing the freeze plans adds very little cost.
* Dirtying extra pages isn't a concern, either; VACUUM will definitely
* set PD_ALL_VISIBLE on affected pages, regardless of freezing strategy.
*/
vacrel->eager_freeze_strategy =
(rel_pages > vacrel->cutoffs.freeze_strategy_threshold_pages ||
!RelationIsPermanent(vacrel->rel));
}
/*
* lazy_scan_skip() -- set up range of skippable blocks using visibility map.
*
@ -1834,12 +1795,10 @@ retry:
* one XID/MXID from before FreezeLimit/MultiXactCutoff is present. Also
* freeze when pruning generated an FPI, if doing so means that we set the
* page all-frozen afterwards (might not happen until final heap pass).
* When ongoing VACUUM opted to use the eager freezing strategy we freeze
* any page that will thereby become all-frozen in the visibility map.
*/
if (pagefrz.freeze_required || tuples_frozen == 0 ||
(prunestate->all_visible && prunestate->all_frozen &&
(fpi_before != pgWalUsage.wal_fpi || vacrel->eager_freeze_strategy)))
fpi_before != pgWalUsage.wal_fpi))
{
/*
* We're freezing the page. Our final NewRelfrozenXid doesn't need to