Add missing assign hook for GUC checkpoint_completion_target

michaelpq · michaelpq · commit 162a48287f1d · 2023-01-19T13:13:32.000+09:00
This is wrong since 88e9823, that has switched the WAL sizing configuration from checkpoint_segments to min_wal_size and max_wal_size. This missed the recalculation of the internal value of the internal "CheckPointSegments", that works as a mapping of the old GUC checkpoint_segments, on reload, for example, and it controls the timing of checkpoints depending on the volume of WAL generated. Most users tend to leave checkpoint_completion_target at 0.9 to smooth the I/O workload, which is why I guess this has gone unnoticed for so long, still it can be useful to tweak and reload the value dynamically in some cases to control the timing of checkpoints. Author: Bharath Rupireddy Discussion: https://postgr.es/m/CALj2ACXgPPAm28mruojSBno+F_=9cTOOxHAywu_dfZPeBdybQw@mail.gmail.com Backpatch-through: 11
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
@@ -3429,7 +3429,7 @@ static struct config_real ConfigureNamesReal[] =
 		},
 		&CheckPointCompletionTarget,
 		0.5, 0.0, 1.0,
-		NULL, NULL, NULL
+		NULL, assign_checkpoint_completion_target, NULL
 	},
 
 	{

Original file line number	Diff line number	Diff line change
`@@ -3429,7 +3429,7 @@ static struct config_real ConfigureNamesReal[] =`
`3429`	`3429`	`},`
`3430`	`3430`	`&CheckPointCompletionTarget,`
`3431`	`3431`	`0.5, 0.0, 1.0,`
`3432`		`- NULL, NULL, NULL`
	`3432`	`+ NULL, assign_checkpoint_completion_target, NULL`
`3433`	`3433`	`},`
`3434`	`3434`
`3435`	`3435`	`{`