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Separate vacuum cost variables from GUCs

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Vacuum code run both by autovacuum workers and a backend doing
VACUUM/ANALYZE previously inspected VacuumCostLimit and VacuumCostDelay,
which are the global variables backing the GUCs vacuum_cost_limit and
vacuum_cost_delay.

Autovacuum workers needed to override these variables with their
own values, derived from autovacuum_vacuum_cost_limit and
autovacuum_vacuum_cost_delay and worker cost limit balancing logic.
This led to confusing code which, in some cases, both derived and
set a new value of VacuumCostLimit from VacuumCostLimit.

In preparation for refreshing these GUC values more often, introduce
new, independent global variables and add a function to update them
using the GUCs and existing logic.

Per suggestion by Kyotaro Horiguchi

Author: Melanie Plageman <melanieplageman@gmail.com>
Reviewed-by: Masahiko Sawada <sawada.mshk@gmail.com>
Reviewed-by: Daniel Gustafsson <daniel@yesql.se>
Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Reviewed-by: Robert Haas <robertmhaas@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/CAAKRu_ZngzqnEODc7LmS1NH04Kt6Y9huSjz5pp7%2BDXhrjDA0gw%40mail.gmail.com
This commit is contained in:
Daniel Gustafsson
2023-04-07 00:54:53 +02:00
parent 71a825194f
commit a85c60a945
5 changed files with 40 additions and 34 deletions
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34
src/backend/postmaster/autovacuum.c
View File

@@ -1773,16 +1773,24 @@ FreeWorkerInfo(int code, Datum arg)
}
/*
* Update the cost-based delay parameters, so that multiple workers consume
* each a fraction of the total available I/O.
* Update vacuum cost-based delay-related parameters for autovacuum workers and
* backends executing VACUUM or ANALYZE using the value of relevant GUCs and
* global state. This must be called during setup for vacuum and after every
* config reload to ensure up-to-date values.
*/
void
AutoVacuumUpdateDelay(void)
VacuumUpdateCosts(void)
{
if (MyWorkerInfo)
{
VacuumCostDelay = MyWorkerInfo->wi_cost_delay;
VacuumCostLimit = MyWorkerInfo->wi_cost_limit;
vacuum_cost_delay = MyWorkerInfo->wi_cost_delay;
vacuum_cost_limit = MyWorkerInfo->wi_cost_limit;
}
else
{
/* Must be explicit VACUUM or ANALYZE */
vacuum_cost_delay = VacuumCostDelay;
vacuum_cost_limit = VacuumCostLimit;
}
}
@@ -2311,8 +2319,6 @@ do_autovacuum(void)
autovac_table *tab;
bool isshared;
bool skipit;
double stdVacuumCostDelay;
int stdVacuumCostLimit;
dlist_iter iter;
CHECK_FOR_INTERRUPTS();
@@ -2415,14 +2421,6 @@ do_autovacuum(void)
continue;
}
/*
* Remember the prevailing values of the vacuum cost GUCs. We have to
* restore these at the bottom of the loop, else we'll compute wrong
* values in the next iteration of autovac_balance_cost().
*/
stdVacuumCostDelay = VacuumCostDelay;
stdVacuumCostLimit = VacuumCostLimit;
/* Must hold AutovacuumLock while mucking with cost balance info */
LWLockAcquire(AutovacuumLock, LW_EXCLUSIVE);
@@ -2436,7 +2434,7 @@ do_autovacuum(void)
autovac_balance_cost();
/* set the active cost parameters from the result of that */
AutoVacuumUpdateDelay();
VacuumUpdateCosts();
/* done */
LWLockRelease(AutovacuumLock);
@@ -2533,10 +2531,6 @@ deleted:
MyWorkerInfo->wi_tableoid = InvalidOid;
MyWorkerInfo->wi_sharedrel = false;
LWLockRelease(AutovacuumScheduleLock);
/* restore vacuum cost GUCs for the next iteration */
VacuumCostDelay = stdVacuumCostDelay;
VacuumCostLimit = stdVacuumCostLimit;
}
/*