Support disabling index bypassing by VACUUM.

Generalize the INDEX_CLEANUP VACUUM parameter (and the corresponding
reloption): make it into a ternary style boolean parameter.  It now
exposes a third option, "auto".  The "auto" option (which is now the
default) enables the "bypass index vacuuming" optimization added by
commit 1e55e7d1.

"VACUUM (INDEX_CLEANUP TRUE)" is redefined to once again make VACUUM
simply do any required index vacuuming, regardless of how few dead
tuples are encountered during the first scan of the target heap relation
(unless there are exactly zero).  This gives users a way of opting out
of the "bypass index vacuuming" optimization, if for whatever reason
that proves necessary.  It is also expected to be used by PostgreSQL
developers as a testing option from time to time.

"VACUUM (INDEX_CLEANUP FALSE)" does the same thing as it always has: it
forcibly disables both index vacuuming and index cleanup.  It's not
expected to be used much in PostgreSQL 14.  The failsafe mechanism added
by commit 1e55e7d1 addresses the same problem in a simpler way.
INDEX_CLEANUP can now be thought of as a testing and compatibility
option.

Author: Peter Geoghegan <[email protected]>
Reviewed-By: Masahiko Sawada <[email protected]>
Reviewed-By: Justin Pryzby <[email protected]>
Discussion: https://postgr.es/m/CAH2-WznrBoCST4_Gxh_G9hA8NzGUbeBGnOUC8FcXcrhqsv6OHQ@mail.gmail.com

1 files changed, 54 insertions, 21 deletions

diff --git a/src/backend/commands/vacuum.c b/src/backend/commands/vacuum.c
index 7421d7cfbd3..5c4bc15b441 100644
--- a/src/backend/commands/vacuum.c
+++ b/src/backend/commands/vacuum.c
@@ -88,7 +88,7 @@ static void vac_truncate_clog(TransactionId frozenXID,
 							  MultiXactId lastSaneMinMulti);
 static bool vacuum_rel(Oid relid, RangeVar *relation, VacuumParams *params);
 static double compute_parallel_delay(void);
-static VacOptTernaryValue get_vacopt_ternary_value(DefElem *def);
+static VacOptValue get_vacoptval_from_boolean(DefElem *def);
 
 /*
  * Primary entry point for manual VACUUM and ANALYZE commands
@@ -109,9 +109,9 @@ ExecVacuum(ParseState *pstate, VacuumStmt *vacstmt, bool isTopLevel)
 	bool		process_toast = true;
 	ListCell   *lc;
 
-	/* Set default value */
-	params.index_cleanup = VACOPT_TERNARY_DEFAULT;
-	params.truncate = VACOPT_TERNARY_DEFAULT;
+	/* index_cleanup and truncate values unspecified for now */
+	params.index_cleanup = VACOPTVALUE_UNSPECIFIED;
+	params.truncate = VACOPTVALUE_UNSPECIFIED;
 
 	/* By default parallel vacuum is enabled */
 	params.nworkers = 0;
@@ -142,11 +142,25 @@ ExecVacuum(ParseState *pstate, VacuumStmt *vacstmt, bool isTopLevel)
 		else if (strcmp(opt->defname, "disable_page_skipping") == 0)
 			disable_page_skipping = defGetBoolean(opt);
 		else if (strcmp(opt->defname, "index_cleanup") == 0)
-			params.index_cleanup = get_vacopt_ternary_value(opt);
+		{
+			/* Interpret no string as the default, which is 'auto' */
+			if (!opt->arg)
+				params.index_cleanup = VACOPTVALUE_AUTO;
+			else
+			{
+				char	   *sval = defGetString(opt);
+
+				/* Try matching on 'auto' string, or fall back on boolean */
+				if (pg_strcasecmp(sval, "auto") == 0)
+					params.index_cleanup = VACOPTVALUE_AUTO;
+				else
+					params.index_cleanup = get_vacoptval_from_boolean(opt);
+			}
+		}
 		else if (strcmp(opt->defname, "process_toast") == 0)
 			process_toast = defGetBoolean(opt);
 		else if (strcmp(opt->defname, "truncate") == 0)
-			params.truncate = get_vacopt_ternary_value(opt);
+			params.truncate = get_vacoptval_from_boolean(opt);
 		else if (strcmp(opt->defname, "parallel") == 0)
 		{
 			if (opt->arg == NULL)
@@ -1938,24 +1952,43 @@ vacuum_rel(Oid relid, RangeVar *relation, VacuumParams *params)
 	lockrelid = rel->rd_lockInfo.lockRelId;
 	LockRelationIdForSession(&lockrelid, lmode);
 
-	/* Set index cleanup option based on reloptions if not yet */
-	if (params->index_cleanup == VACOPT_TERNARY_DEFAULT)
+	/*
+	 * Set index_cleanup option based on index_cleanup reloption if it wasn't
+	 * specified in VACUUM command, or when running in an autovacuum worker
+	 */
+	if (params->index_cleanup == VACOPTVALUE_UNSPECIFIED)
 	{
-		if (rel->rd_options == NULL ||
-			((StdRdOptions *) rel->rd_options)->vacuum_index_cleanup)
-			params->index_cleanup = VACOPT_TERNARY_ENABLED;
+		StdRdOptIndexCleanup vacuum_index_cleanup;
+
+		if (rel->rd_options == NULL)
+			vacuum_index_cleanup = STDRD_OPTION_VACUUM_INDEX_CLEANUP_AUTO;
+		else
+			vacuum_index_cleanup =
+				((StdRdOptions *) rel->rd_options)->vacuum_index_cleanup;
+
+		if (vacuum_index_cleanup == STDRD_OPTION_VACUUM_INDEX_CLEANUP_AUTO)
+			params->index_cleanup = VACOPTVALUE_AUTO;
+		else if (vacuum_index_cleanup == STDRD_OPTION_VACUUM_INDEX_CLEANUP_ON)
+			params->index_cleanup = VACOPTVALUE_ENABLED;
 		else
-			params->index_cleanup = VACOPT_TERNARY_DISABLED;
+		{
+			Assert(vacuum_index_cleanup ==
+				   STDRD_OPTION_VACUUM_INDEX_CLEANUP_OFF);
+			params->index_cleanup = VACOPTVALUE_DISABLED;
+		}
 	}
 
-	/* Set truncate option based on reloptions if not yet */
-	if (params->truncate == VACOPT_TERNARY_DEFAULT)
+	/*
+	 * Set truncate option based on truncate reloption if it wasn't specified
+	 * in VACUUM command, or when running in an autovacuum worker
+	 */
+	if (params->truncate == VACOPTVALUE_UNSPECIFIED)
 	{
 		if (rel->rd_options == NULL ||
 			((StdRdOptions *) rel->rd_options)->vacuum_truncate)
-			params->truncate = VACOPT_TERNARY_ENABLED;
+			params->truncate = VACOPTVALUE_ENABLED;
 		else
-			params->truncate = VACOPT_TERNARY_DISABLED;
+			params->truncate = VACOPTVALUE_DISABLED;
 	}
 
 	/*
@@ -2217,11 +2250,11 @@ compute_parallel_delay(void)
 /*
  * A wrapper function of defGetBoolean().
  *
- * This function returns VACOPT_TERNARY_ENABLED and VACOPT_TERNARY_DISABLED
- * instead of true and false.
+ * This function returns VACOPTVALUE_ENABLED and VACOPTVALUE_DISABLED instead
+ * of true and false.
  */
-static VacOptTernaryValue
-get_vacopt_ternary_value(DefElem *def)
+static VacOptValue
+get_vacoptval_from_boolean(DefElem *def)
 {
-	return defGetBoolean(def) ? VACOPT_TERNARY_ENABLED : VACOPT_TERNARY_DISABLED;
+	return defGetBoolean(def) ? VACOPTVALUE_ENABLED : VACOPTVALUE_DISABLED;
 }