v2-0001-Generalize-VACUUM-s-INDEX_CLEANUP-option.patch

From b7813aee4f9770fe23cf64eaffc8c119a517f3f3 Mon Sep 17 00:00:00 2001
From: Peter Geoghegan <pg@bowt.ie>
Date: Wed, 26 May 2021 17:17:05 -0700
Subject: [PATCH v2] Generalize VACUUM's INDEX_CLEANUP option.

Generalize the reloption INDEX_CLEANUP to enable users to disable the
index vacuum bypassing optimization added by commit 5100010e, as well as
any similar optimizations that may be added in the future.

The reloption is now a trinary boolean style enum whose default is
'auto', which preserves the current VACUUM behavior.  Explicitly setting
INDEX_CLEANUP to 'on' now avoids any optimizations that skip index
vacuuming, though it doesn't have any effect on the failsafe mechanism.

The INDEX_CLEANUP reloption was originally added by commit a96c41fe as
an emergency option to allow DBAs to opt out of index vacuuming in
extreme cases -- cases where the likely alternative is an anti-wraparoud
failure.  The reloption can still be used for that, but it seems like a
much less useful option now that VACUUM has the failsafe mechanism added
by commit 1e55e7d1.

Author: Peter Geoghegan <pg@bowt.ie>
Reviewed-By: Masahiko Sawada <sawada.mshk@gmail.com>
Discussion: https://postgr.es/m/CAH2-Wz=w7r1dpFEr=ija2XFn798wd41+6QUSbkcc8HmWKhEhdA@mail.gmail.com
---
 src/include/commands/vacuum.h          |  4 +-
 src/include/utils/rel.h                | 15 ++++++-
 src/backend/access/common/reloptions.c | 35 +++++++++++----
 src/backend/access/heap/vacuumlazy.c   | 48 ++++++++++++++------
 src/backend/commands/vacuum.c          | 47 +++++++++++++++++---
 src/bin/scripts/vacuumdb.c             | 61 +++++++++++++++++++++-----
 doc/src/sgml/ref/create_table.sgml     | 21 +++++----
 doc/src/sgml/ref/vacuum.sgml           | 43 +++++++++++-------
 doc/src/sgml/ref/vacuumdb.sgml         | 15 +++++++
 src/test/regress/expected/vacuum.out   |  8 ++--
 src/test/regress/sql/vacuum.sql        |  8 ++--
 11 files changed, 236 insertions(+), 69 deletions(-)

diff --git a/src/include/commands/vacuum.h b/src/include/commands/vacuum.h
index cb27257bb6..a357ce148d 100644
--- a/src/include/commands/vacuum.h
+++ b/src/include/commands/vacuum.h
@@ -188,11 +188,13 @@ typedef struct VacAttrStats
  * A ternary value used by vacuum parameters.
  *
  * DEFAULT value is used to determine the value based on other
- * configurations, e.g. reloptions.
+ * configurations, e.g. reloptions.  AUTO value is used by
+ * index_cleanup option only.
  */
 typedef enum VacOptTernaryValue
 {
 	VACOPT_TERNARY_DEFAULT = 0,
+	VACOPT_TERNARY_AUTO,
 	VACOPT_TERNARY_DISABLED,
 	VACOPT_TERNARY_ENABLED,
 } VacOptTernaryValue;
diff --git a/src/include/utils/rel.h b/src/include/utils/rel.h
index 774ac5b2b1..6924ed730d 100644
--- a/src/include/utils/rel.h
+++ b/src/include/utils/rel.h
@@ -307,6 +307,19 @@ typedef struct AutoVacOpts
 	float8		analyze_scale_factor;
 } AutoVacOpts;
 
+/*
+ * A ternary value used by vacuum parameters.
+ *
+ * DEFAULT value is used to determine the value based on other
+ * configurations, e.g. reloptions.
+ */
+typedef enum StdRdOptIndexCleanup
+{
+	STDRD_OPTION_VACUUM_INDEX_CLEANUP_AUTO = 0,
+	STDRD_OPTION_VACUUM_INDEX_CLEANUP_OFF,
+	STDRD_OPTION_VACUUM_INDEX_CLEANUP_ON
+} StdRdOptIndexCleanup;
+
 typedef struct StdRdOptions
 {
 	int32		vl_len_;		/* varlena header (do not touch directly!) */
@@ -316,7 +329,7 @@ typedef struct StdRdOptions
 	AutoVacOpts autovacuum;		/* autovacuum-related options */
 	bool		user_catalog_table; /* use as an additional catalog relation */
 	int			parallel_workers;	/* max number of parallel workers */
-	bool		vacuum_index_cleanup;	/* enables index vacuuming and cleanup */
+	StdRdOptIndexCleanup vacuum_index_cleanup;	/* controls index vacuuming */
 	bool		vacuum_truncate;	/* enables vacuum to truncate a relation */
 } StdRdOptions;
 
diff --git a/src/backend/access/common/reloptions.c b/src/backend/access/common/reloptions.c
index 5554275e64..7ef934cbc4 100644
--- a/src/backend/access/common/reloptions.c
+++ b/src/backend/access/common/reloptions.c
@@ -140,15 +140,6 @@ static relopt_bool boolRelOpts[] =
 		},
 		false
 	},
-	{
-		{
-			"vacuum_index_cleanup",
-			"Enables index vacuuming and index cleanup",
-			RELOPT_KIND_HEAP | RELOPT_KIND_TOAST,
-			ShareUpdateExclusiveLock
-		},
-		true
-	},
 	{
 		{
 			"vacuum_truncate",
@@ -474,6 +465,21 @@ static relopt_real realRelOpts[] =
 	{{NULL}}
 };
 
+/* values from StdRdOptIndexCleanup */
+relopt_enum_elt_def StdRdOptIndexCleanupValues[] =
+{
+	{"auto", STDRD_OPTION_VACUUM_INDEX_CLEANUP_AUTO},
+	{"on", STDRD_OPTION_VACUUM_INDEX_CLEANUP_ON},
+	{"off", STDRD_OPTION_VACUUM_INDEX_CLEANUP_OFF},
+	{"true", STDRD_OPTION_VACUUM_INDEX_CLEANUP_ON},
+	{"false", STDRD_OPTION_VACUUM_INDEX_CLEANUP_OFF},
+	{"yes", STDRD_OPTION_VACUUM_INDEX_CLEANUP_ON},
+	{"no", STDRD_OPTION_VACUUM_INDEX_CLEANUP_OFF},
+	{"1", STDRD_OPTION_VACUUM_INDEX_CLEANUP_ON},
+	{"0", STDRD_OPTION_VACUUM_INDEX_CLEANUP_OFF},
+	{(const char *) NULL}		/* list terminator */
+};
+
 /* values from GistOptBufferingMode */
 relopt_enum_elt_def gistBufferingOptValues[] =
 {
@@ -494,6 +500,17 @@ relopt_enum_elt_def viewCheckOptValues[] =
 
 static relopt_enum enumRelOpts[] =
 {
+	{
+		{
+			"vacuum_index_cleanup",
+			"Forces or disables index vacuuming and index cleanup",
+			RELOPT_KIND_HEAP | RELOPT_KIND_TOAST,
+			ShareUpdateExclusiveLock
+		},
+		StdRdOptIndexCleanupValues,
+		STDRD_OPTION_VACUUM_INDEX_CLEANUP_AUTO,
+		gettext_noop("Valid values are \"on\", \"off\", and \"auto\".")
+	},
 	{
 		{
 			"buffering",
diff --git a/src/backend/access/heap/vacuumlazy.c b/src/backend/access/heap/vacuumlazy.c
index 88db2e2cfc..8c7f72c775 100644
--- a/src/backend/access/heap/vacuumlazy.c
+++ b/src/backend/access/heap/vacuumlazy.c
@@ -313,6 +313,8 @@ typedef struct LVRelState
 	bool		do_index_cleanup;
 	/* Wraparound failsafe in effect? (implies !do_index_vacuuming) */
 	bool		do_failsafe;
+	/* Consider bypass optimization? */
+	bool		do_bypass_optimization;
 
 	/* Buffer access strategy and parallel state */
 	BufferAccessStrategy bstrategy;
@@ -405,7 +407,7 @@ static void lazy_scan_prune(LVRelState *vacrel, Buffer buf,
 							BlockNumber blkno, Page page,
 							GlobalVisState *vistest,
 							LVPagePruneState *prunestate);
-static void lazy_vacuum(LVRelState *vacrel, bool onecall);
+static void lazy_vacuum(LVRelState *vacrel);
 static bool lazy_vacuum_all_indexes(LVRelState *vacrel);
 static void lazy_vacuum_heap_rel(LVRelState *vacrel);
 static int	lazy_vacuum_heap_page(LVRelState *vacrel, BlockNumber blkno,
@@ -509,6 +511,7 @@ heap_vacuum_rel(Relation rel, VacuumParams *params,
 	Assert(params != NULL);
 	Assert(params->index_cleanup != VACOPT_TERNARY_DEFAULT);
 	Assert(params->truncate != VACOPT_TERNARY_DEFAULT);
+	Assert(params->truncate != VACOPT_TERNARY_AUTO);
 
 	/* measure elapsed time iff autovacuum logging requires it */
 	if (IsAutoVacuumWorkerProcess() && params->log_min_duration >= 0)
@@ -557,14 +560,33 @@ heap_vacuum_rel(Relation rel, VacuumParams *params,
 	vacrel->rel = rel;
 	vac_open_indexes(vacrel->rel, RowExclusiveLock, &vacrel->nindexes,
 					 &vacrel->indrels);
+
+	/*
+	 * index_cleanup either disables index vacuuming and cleanup or forces it
+	 * to go ahead when we would otherwise apply the bypass optimization.  The
+	 * default is 'auto', which leaves the final decision up to lazy_vacuum().
+	 */
 	vacrel->do_index_vacuuming = true;
 	vacrel->do_index_cleanup = true;
 	vacrel->do_failsafe = false;
+	vacrel->do_bypass_optimization = true;
 	if (params->index_cleanup == VACOPT_TERNARY_DISABLED)
 	{
+		/* Force disable index vacuuming up-front */
 		vacrel->do_index_vacuuming = false;
 		vacrel->do_index_cleanup = false;
 	}
+	else if (params->index_cleanup == VACOPT_TERNARY_ENABLED)
+	{
+		/* Force index vacuuming (never bypass) */
+		vacrel->do_bypass_optimization = false;
+	}
+	else
+	{
+		/* Default/auto, make all decisions dynamically */
+		Assert(params->index_cleanup == VACOPT_TERNARY_AUTO);
+	}
+
 	vacrel->bstrategy = bstrategy;
 	vacrel->old_rel_pages = rel->rd_rel->relpages;
 	vacrel->old_live_tuples = rel->rd_rel->reltuples;
@@ -893,8 +915,7 @@ lazy_scan_heap(LVRelState *vacrel, VacuumParams *params, bool aggressive)
 				next_fsm_block_to_vacuum;
 	PGRUsage	ru0;
 	Buffer		vmbuffer = InvalidBuffer;
-	bool		skipping_blocks,
-				have_vacuumed_indexes = false;
+	bool		skipping_blocks;
 	StringInfoData buf;
 	const int	initprog_index[] = {
 		PROGRESS_VACUUM_PHASE,
@@ -1166,8 +1187,8 @@ lazy_scan_heap(LVRelState *vacrel, VacuumParams *params, bool aggressive)
 			}
 
 			/* Remove the collected garbage tuples from table and indexes */
-			lazy_vacuum(vacrel, false);
-			have_vacuumed_indexes = true;
+			vacrel->do_bypass_optimization = false;
+			lazy_vacuum(vacrel);
 
 			/*
 			 * Vacuum the Free Space Map to make newly-freed space visible on
@@ -1579,7 +1600,7 @@ lazy_scan_heap(LVRelState *vacrel, VacuumParams *params, bool aggressive)
 
 	/* If any tuples need to be deleted, perform final vacuum cycle */
 	if (dead_tuples->num_tuples > 0)
-		lazy_vacuum(vacrel, !have_vacuumed_indexes);
+		lazy_vacuum(vacrel);
 
 	/*
 	 * Vacuum the remainder of the Free Space Map.  We must do this whether or
@@ -2064,9 +2085,9 @@ retry:
  * wraparound.
  */
 static void
-lazy_vacuum(LVRelState *vacrel, bool onecall)
+lazy_vacuum(LVRelState *vacrel)
 {
-	bool		do_bypass_optimization;
+	bool		bypass;
 
 	/* Should not end up here with no indexes */
 	Assert(vacrel->nindexes > 0);
@@ -2099,8 +2120,8 @@ lazy_vacuum(LVRelState *vacrel, bool onecall)
 	 * It's far easier to ensure that 99%+ of all UPDATEs against a table use
 	 * HOT through careful tuning.
 	 */
-	do_bypass_optimization = false;
-	if (onecall && vacrel->rel_pages > 0)
+	bypass = false;
+	if (vacrel->do_bypass_optimization && vacrel->rel_pages > 0)
 	{
 		BlockNumber threshold;
 
@@ -2132,12 +2153,11 @@ lazy_vacuum(LVRelState *vacrel, bool onecall)
 		 * expanded to cover more cases then this may need to be reconsidered.
 		 */
 		threshold = (double) vacrel->rel_pages * BYPASS_THRESHOLD_PAGES;
-		do_bypass_optimization =
-			(vacrel->lpdead_item_pages < threshold &&
-			 vacrel->lpdead_items < MAXDEADTUPLES(32L * 1024L * 1024L));
+		bypass = (vacrel->lpdead_item_pages < threshold &&
+				  vacrel->lpdead_items < MAXDEADTUPLES(32L * 1024L * 1024L));
 	}
 
-	if (do_bypass_optimization)
+	if (bypass)
 	{
 		/*
 		 * There are almost zero TIDs.  Behave as if there were precisely
diff --git a/src/backend/commands/vacuum.c b/src/backend/commands/vacuum.c
index 7421d7cfbd..9190e9cb70 100644
--- a/src/backend/commands/vacuum.c
+++ b/src/backend/commands/vacuum.c
@@ -142,7 +142,21 @@ 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 = VACOPT_TERNARY_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 = VACOPT_TERNARY_AUTO;
+				else
+					params.index_cleanup = get_vacopt_ternary_value(opt);
+			}
+		}
 		else if (strcmp(opt->defname, "process_toast") == 0)
 			process_toast = defGetBoolean(opt);
 		else if (strcmp(opt->defname, "truncate") == 0)
@@ -1938,17 +1952,37 @@ 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 */
+	/*
+	 * Set index cleanup option based on vacuum_index_cleanup reloptions if
+	 * not yet.  This is a ternary style boolean option.
+	 */
 	if (params->index_cleanup == VACOPT_TERNARY_DEFAULT)
 	{
-		if (rel->rd_options == NULL ||
-			((StdRdOptions *) rel->rd_options)->vacuum_index_cleanup)
+		StdRdOptIndexCleanup vacuum_index_cleanup;
+
+		/* The reloption default is 'auto', just like the VACUUM option */
+		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 = VACOPT_TERNARY_AUTO;
+		else if (vacuum_index_cleanup == STDRD_OPTION_VACUUM_INDEX_CLEANUP_ON)
 			params->index_cleanup = VACOPT_TERNARY_ENABLED;
 		else
+		{
+			Assert(vacuum_index_cleanup ==
+				   STDRD_OPTION_VACUUM_INDEX_CLEANUP_OFF);
 			params->index_cleanup = VACOPT_TERNARY_DISABLED;
+		}
 	}
 
-	/* Set truncate option based on reloptions if not yet */
+	/*
+	 * Set index cleanup option based on truncate reloptions if not yet.  This
+	 * is a simple boolean reloption.
+	 */
 	if (params->truncate == VACOPT_TERNARY_DEFAULT)
 	{
 		if (rel->rd_options == NULL ||
@@ -2219,6 +2253,9 @@ compute_parallel_delay(void)
  *
  * This function returns VACOPT_TERNARY_ENABLED and VACOPT_TERNARY_DISABLED
  * instead of true and false.
+ *
+ * There is also a VACOPT_TERNARY_AUTO value that is used only by the
+ * INDEX_CLEANUP option.  We don't handle that here.
  */
 static VacOptTernaryValue
 get_vacopt_ternary_value(DefElem *def)
diff --git a/src/bin/scripts/vacuumdb.c b/src/bin/scripts/vacuumdb.c
index 069a861aab..7df75602eb 100644
--- a/src/bin/scripts/vacuumdb.c
+++ b/src/bin/scripts/vacuumdb.c
@@ -39,7 +39,8 @@ typedef struct vacuumingOptions
 	int			min_mxid_age;
 	int			parallel_workers;	/* >= 0 indicates user specified the
 									 * parallel degree, otherwise -1 */
-	bool		do_index_cleanup;
+	bool		no_index_cleanup;
+	bool		force_index_cleanup;
 	bool		do_truncate;
 	bool		process_toast;
 } vacuumingOptions;
@@ -99,8 +100,9 @@ main(int argc, char *argv[])
 		{"min-xid-age", required_argument, NULL, 6},
 		{"min-mxid-age", required_argument, NULL, 7},
 		{"no-index-cleanup", no_argument, NULL, 8},
-		{"no-truncate", no_argument, NULL, 9},
-		{"no-process-toast", no_argument, NULL, 10},
+		{"force-index-cleanup", no_argument, NULL, 9},
+		{"no-truncate", no_argument, NULL, 10},
+		{"no-process-toast", no_argument, NULL, 11},
 		{NULL, 0, NULL, 0}
 	};
 
@@ -126,7 +128,8 @@ main(int argc, char *argv[])
 	/* initialize options */
 	memset(&vacopts, 0, sizeof(vacopts));
 	vacopts.parallel_workers = -1;
-	vacopts.do_index_cleanup = true;
+	vacopts.no_index_cleanup = false;
+	vacopts.force_index_cleanup = false;
 	vacopts.do_truncate = true;
 	vacopts.process_toast = true;
 
@@ -233,12 +236,15 @@ main(int argc, char *argv[])
 				}
 				break;
 			case 8:
-				vacopts.do_index_cleanup = false;
+				vacopts.no_index_cleanup = true;
 				break;
 			case 9:
-				vacopts.do_truncate = false;
+				vacopts.force_index_cleanup = true;
 				break;
 			case 10:
+				vacopts.do_truncate = false;
+				break;
+			case 11:
 				vacopts.process_toast = false;
 				break;
 			default:
@@ -285,12 +291,18 @@ main(int argc, char *argv[])
 						 "disable-page-skipping");
 			exit(1);
 		}
-		if (!vacopts.do_index_cleanup)
+		if (vacopts.no_index_cleanup)
 		{
 			pg_log_error("cannot use the \"%s\" option when performing only analyze",
 						 "no-index-cleanup");
 			exit(1);
 		}
+		if (vacopts.force_index_cleanup)
+		{
+			pg_log_error("cannot use the \"%s\" option when performing only analyze",
+						 "force-index-cleanup");
+			exit(1);
+		}
 		if (!vacopts.do_truncate)
 		{
 			pg_log_error("cannot use the \"%s\" option when performing only analyze",
@@ -323,6 +335,14 @@ main(int argc, char *argv[])
 		}
 	}
 
+	/* Prohibit --no-index-cleanup and --force-index-cleanup together */
+	if (vacopts.no_index_cleanup && vacopts.force_index_cleanup)
+	{
+		pg_log_error("cannot use the \"%s\" option with the \"%s\" option",
+					 "no-index-cleanup", "force-index-cleanup");
+		exit(1);
+	}
+
 	/* fill cparams except for dbname, which is set below */
 	cparams.pghost = host;
 	cparams.pgport = port;
@@ -453,7 +473,7 @@ vacuum_one_database(ConnParams *cparams,
 		exit(1);
 	}
 
-	if (!vacopts->do_index_cleanup && PQserverVersion(conn) < 120000)
+	if (vacopts->no_index_cleanup && PQserverVersion(conn) < 120000)
 	{
 		PQfinish(conn);
 		pg_log_error("cannot use the \"%s\" option on server versions older than PostgreSQL %s",
@@ -461,6 +481,14 @@ vacuum_one_database(ConnParams *cparams,
 		exit(1);
 	}
 
+	if (vacopts->force_index_cleanup && PQserverVersion(conn) < 120000)
+	{
+		PQfinish(conn);
+		pg_log_error("cannot use the \"%s\" option on server versions older than PostgreSQL %s",
+					 "force-index-cleanup", "12");
+		exit(1);
+	}
+
 	if (!vacopts->do_truncate && PQserverVersion(conn) < 120000)
 	{
 		PQfinish(conn);
@@ -878,10 +906,23 @@ prepare_vacuum_command(PQExpBuffer sql, int serverVersion,
 				appendPQExpBuffer(sql, "%sDISABLE_PAGE_SKIPPING", sep);
 				sep = comma;
 			}
-			if (!vacopts->do_index_cleanup)
+			if (vacopts->no_index_cleanup)
 			{
-				/* INDEX_CLEANUP is supported since v12 */
+				/* "INDEX_CLEANUP FALSE" has been supported since v12 */
 				Assert(serverVersion >= 120000);
+				Assert(!vacopts->force_index_cleanup);
+				appendPQExpBuffer(sql, "%sINDEX_CLEANUP FALSE", sep);
+				sep = comma;
+			}
+			if (vacopts->force_index_cleanup)
+			{
+				/*
+				 * "INDEX_CLEANUP TRUE" has been supported since v12. Though
+				 * the --force-index-cleanup vacuumdb option was only added in
+				 * v14, it still works in the same way on v12+.
+				 */
+				Assert(serverVersion >= 120000);
+				Assert(!vacopts->no_index_cleanup);
 				appendPQExpBuffer(sql, "%sINDEX_CLEANUP FALSE", sep);
 				sep = comma;
 			}
diff --git a/doc/src/sgml/ref/create_table.sgml b/doc/src/sgml/ref/create_table.sgml
index c6d0a35e50..a5193eeaac 100644
--- a/doc/src/sgml/ref/create_table.sgml
+++ b/doc/src/sgml/ref/create_table.sgml
@@ -1473,20 +1473,25 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
    </varlistentry>
 
    <varlistentry id="reloption-vacuum-index-cleanup" xreflabel="vacuum_index_cleanup">
-    <term><literal>vacuum_index_cleanup</literal>, <literal>toast.vacuum_index_cleanup</literal> (<type>boolean</type>)
+    <term><literal>vacuum_index_cleanup</literal>, <literal>toast.vacuum_index_cleanup</literal> (<type>enum</type>)
     <indexterm>
      <primary><varname>vacuum_index_cleanup</varname> storage parameter</primary>
     </indexterm>
     </term>
     <listitem>
      <para>
-      Enables or disables index cleanup when <command>VACUUM</command> is
-      run on this table.  The default value is <literal>true</literal>.
-      Disabling index cleanup can speed up <command>VACUUM</command> very
-      significantly, but may also lead to severely bloated indexes if table
-      modifications are frequent.  The <literal>INDEX_CLEANUP</literal>
-      parameter of <link linkend="sql-vacuum"><command>VACUUM</command></link>, if specified, overrides
-      the value of this option.
+      Disables or forces index cleanup when <command>VACUUM</command>
+      is run on this table.  The default value is
+      <literal>AUTO</literal>.  With <literal>OFF</literal> index
+      cleanup is disabled, with <literal>ON</literal> it is enabled,
+      and with <literal>AUTO</literal> the decision is made
+      dynamically by a <command>VACUUM</command> cost model.
+      Disabling index cleanup can speed up <command>VACUUM</command>
+      very significantly, but may also lead to severely bloated
+      indexes if table modifications are frequent.
+      The <literal>INDEX_CLEANUP</literal> parameter of <link
+       linkend="sql-vacuum"><command>VACUUM</command></link>, if
+      specified, overrides the value of this option.
      </para>
     </listitem>
    </varlistentry>
diff --git a/doc/src/sgml/ref/vacuum.sgml b/doc/src/sgml/ref/vacuum.sgml
index 5f67c9d18b..3a32144ad0 100644
--- a/doc/src/sgml/ref/vacuum.sgml
+++ b/doc/src/sgml/ref/vacuum.sgml
@@ -32,7 +32,7 @@ VACUUM [ FULL ] [ FREEZE ] [ VERBOSE ] [ ANALYZE ] [ <replaceable class="paramet
     ANALYZE [ <replaceable class="parameter">boolean</replaceable> ]
     DISABLE_PAGE_SKIPPING [ <replaceable class="parameter">boolean</replaceable> ]
     SKIP_LOCKED [ <replaceable class="parameter">boolean</replaceable> ]
-    INDEX_CLEANUP [ <replaceable class="parameter">boolean</replaceable> ]
+    INDEX_CLEANUP [ <replaceable class="parameter">enum</replaceable> ]
     PROCESS_TOAST [ <replaceable class="parameter">boolean</replaceable> ]
     TRUNCATE [ <replaceable class="parameter">boolean</replaceable> ]
     PARALLEL <replaceable class="parameter">integer</replaceable>
@@ -193,20 +193,24 @@ VACUUM [ FULL ] [ FREEZE ] [ VERBOSE ] [ ANALYZE ] [ <replaceable class="paramet
     <term><literal>INDEX_CLEANUP</literal></term>
     <listitem>
      <para>
-      Specifies that <command>VACUUM</command> should attempt to remove
-      index entries pointing to dead tuples.  This is normally the desired
-      behavior and is the default unless the
-      <literal>vacuum_index_cleanup</literal> option has been set to false
-      for the table to be vacuumed.  Setting this option to false may be
-      useful when it is necessary to make vacuum run as quickly as possible,
-      for example to avoid imminent transaction ID wraparound
-      (see <xref linkend="vacuum-for-wraparound"/>).  However, if index
-      cleanup is not performed regularly, performance may suffer, because
-      as the table is modified, indexes will accumulate dead tuples
-      and the table itself will accumulate dead line pointers that cannot be
-      removed until index cleanup is completed.  This option has no effect
-      for tables that do not have an index and is ignored if the
-      <literal>FULL</literal> option is used.
+      Specifies when and how <command>VACUUM</command> should remove
+      index entries pointing to dead tuples.  The default setting is
+      <literal>AUTO</literal>, which makes vacuum remove index entries
+      unless the table has an insignificant number of dead tuples.
+      Other valid settings are <literal>OFF</literal>, which forces
+      index cleanup to be bypassed in all cases, and
+      <literal>ON</literal>, which prevents vacuum from considering
+      bypassing index cleanup in cases where there is more than zero
+      dead tuples.
+     </para>
+     <para>
+      If <literal>INDEX_CLEANUP</literal> is set to
+      <literal>OFF</literal> performance may suffer, because as the
+      table is modified, indexes will accumulate dead tuples and the
+      table itself will accumulate dead line pointers that cannot be
+      removed until index cleanup is completed.  This option has no
+      effect for tables that do not have an index and is ignored if
+      the <literal>FULL</literal> option is used.
      </para>
     </listitem>
    </varlistentry>
@@ -284,6 +288,15 @@ VACUUM [ FULL ] [ FREEZE ] [ VERBOSE ] [ ANALYZE ] [ <replaceable class="paramet
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term><replaceable class="parameter">enum</replaceable></term>
+    <listitem>
+     <para>
+      Specifies an enumeration value passed to the selected option.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><replaceable class="parameter">integer</replaceable></term>
     <listitem>
diff --git a/doc/src/sgml/ref/vacuumdb.sgml b/doc/src/sgml/ref/vacuumdb.sgml
index 3e7f7ed68f..537724184e 100644
--- a/doc/src/sgml/ref/vacuumdb.sgml
+++ b/doc/src/sgml/ref/vacuumdb.sgml
@@ -244,6 +244,21 @@ PostgreSQL documentation
       </listitem>
      </varlistentry>
 
+     <varlistentry>
+      <term><option>--no-index-cleanup</option></term>
+      <listitem>
+       <para>
+        Always remove index entries pointing to dead tuples.
+       </para>
+       <note>
+        <para>
+         This option is only available for servers running
+         <productname>PostgreSQL</productname> 12 and later.
+        </para>
+       </note>
+      </listitem>
+     </varlistentry>
+
      <varlistentry>
       <term><option>--no-process-toast</option></term>
       <listitem>
diff --git a/src/test/regress/expected/vacuum.out b/src/test/regress/expected/vacuum.out
index 5e657849aa..e5771462d5 100644
--- a/src/test/regress/expected/vacuum.out
+++ b/src/test/regress/expected/vacuum.out
@@ -146,13 +146,15 @@ VACUUM no_index_cleanup;
 -- Both parent relation and toast are cleaned up.
 ALTER TABLE no_index_cleanup SET (vacuum_index_cleanup = true);
 VACUUM no_index_cleanup;
+ALTER TABLE no_index_cleanup SET (vacuum_index_cleanup = auto);
+VACUUM no_index_cleanup;
 -- Parameter is set for both the parent table and its toast relation.
 INSERT INTO no_index_cleanup(i, t) VALUES (generate_series(31,60),
     repeat('1234567890',269));
 DELETE FROM no_index_cleanup WHERE i < 45;
 -- Only toast index is cleaned up.
-ALTER TABLE no_index_cleanup SET (vacuum_index_cleanup = false,
-    toast.vacuum_index_cleanup = true);
+ALTER TABLE no_index_cleanup SET (vacuum_index_cleanup = off,
+    toast.vacuum_index_cleanup = yes);
 VACUUM no_index_cleanup;
 -- Only parent is cleaned up.
 ALTER TABLE no_index_cleanup SET (vacuum_index_cleanup = true,
@@ -160,7 +162,7 @@ ALTER TABLE no_index_cleanup SET (vacuum_index_cleanup = true,
 VACUUM no_index_cleanup;
 -- Test some extra relations.
 VACUUM (INDEX_CLEANUP FALSE) vaccluster;
-VACUUM (INDEX_CLEANUP FALSE) vactst; -- index cleanup option is ignored if no indexes
+VACUUM (INDEX_CLEANUP AUTO) vactst; -- index cleanup option is ignored if no indexes
 VACUUM (INDEX_CLEANUP FALSE, FREEZE TRUE) vaccluster;
 -- TRUNCATE option
 CREATE TABLE vac_truncate_test(i INT NOT NULL, j text)
diff --git a/src/test/regress/sql/vacuum.sql b/src/test/regress/sql/vacuum.sql
index 93fd258fc0..f220fc28a7 100644
--- a/src/test/regress/sql/vacuum.sql
+++ b/src/test/regress/sql/vacuum.sql
@@ -127,13 +127,15 @@ VACUUM no_index_cleanup;
 -- Both parent relation and toast are cleaned up.
 ALTER TABLE no_index_cleanup SET (vacuum_index_cleanup = true);
 VACUUM no_index_cleanup;
+ALTER TABLE no_index_cleanup SET (vacuum_index_cleanup = auto);
+VACUUM no_index_cleanup;
 -- Parameter is set for both the parent table and its toast relation.
 INSERT INTO no_index_cleanup(i, t) VALUES (generate_series(31,60),
     repeat('1234567890',269));
 DELETE FROM no_index_cleanup WHERE i < 45;
 -- Only toast index is cleaned up.
-ALTER TABLE no_index_cleanup SET (vacuum_index_cleanup = false,
-    toast.vacuum_index_cleanup = true);
+ALTER TABLE no_index_cleanup SET (vacuum_index_cleanup = off,
+    toast.vacuum_index_cleanup = yes);
 VACUUM no_index_cleanup;
 -- Only parent is cleaned up.
 ALTER TABLE no_index_cleanup SET (vacuum_index_cleanup = true,
@@ -141,7 +143,7 @@ ALTER TABLE no_index_cleanup SET (vacuum_index_cleanup = true,
 VACUUM no_index_cleanup;
 -- Test some extra relations.
 VACUUM (INDEX_CLEANUP FALSE) vaccluster;
-VACUUM (INDEX_CLEANUP FALSE) vactst; -- index cleanup option is ignored if no indexes
+VACUUM (INDEX_CLEANUP AUTO) vactst; -- index cleanup option is ignored if no indexes
 VACUUM (INDEX_CLEANUP FALSE, FREEZE TRUE) vaccluster;
 
 -- TRUNCATE option
-- 
2.27.0