Add missing assign hook for GUC checkpoint_completion_target

michaelpq · michaelpq · commit 7e8a80d1fefd · 2023-01-19T13:13:05.000+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_tables.c b/src/backend/utils/misc/guc_tables.c
@@ -3713,7 +3713,7 @@ struct config_real ConfigureNamesReal[] =
 		},
 		&CheckPointCompletionTarget,
 		0.9, 0.0, 1.0,
-		NULL, NULL, NULL
+		NULL, assign_checkpoint_completion_target, NULL
 	},
 
 	{

Original file line number	Diff line number	Diff line change
`@@ -3713,7 +3713,7 @@ struct config_real ConfigureNamesReal[] =`
`3713`	`3713`	`},`
`3714`	`3714`	`&CheckPointCompletionTarget,`
`3715`	`3715`	`0.9, 0.0, 1.0,`
`3716`		`- NULL, NULL, NULL`
	`3716`	`+ NULL, assign_checkpoint_completion_target, NULL`
`3717`	`3717`	`},`
`3718`	`3718`
`3719`	`3719`	`{`