postgres
diff --git a/‎doc/src/sgml/config.sgml
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+6-2 b/‎doc/src/sgml/config.sgml
Copy file name to clipboardExpand all lines: doc/src/sgml/config.sgml
+6-2
diff --git a/‎src/backend/access/heap/vacuumlazy.c
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+7 b/‎src/backend/access/heap/vacuumlazy.c
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+7
diff --git a/‎src/backend/commands/vacuum.c
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+5-3 b/‎src/backend/commands/vacuum.c
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+5-3
@@ -9320,8 +9320,12 @@ COPY postgres_log FROM '/full/path/to/logfile.csv' WITH csv;
        </para>
        <para>
         When the failsafe is triggered, any cost-based delay that is
-        in effect will no longer be applied, and further non-essential
-        maintenance tasks (such as index vacuuming) are bypassed.
+        in effect will no longer be applied, further non-essential
+        maintenance tasks (such as index vacuuming) are bypassed, and any
+        <glossterm linkend="glossary-buffer-access-strategy">Buffer Access Strategy</glossterm>
+        in use will be disabled resulting in <command>VACUUM</command> being
+        free to make use of all of
+        <glossterm linkend="glossary-shared-memory">shared buffers</glossterm>.
        </para>
        <para>
         The default is 1.6 billion transactions.  Although users can
 
@@ -2623,6 +2623,13 @@ lazy_check_wraparound_failsafe(LVRelState *vacrel)
 	{
 		vacrel->failsafe_active = true;
 
+		/*
+		 * Abandon use of a buffer access strategy to allow use of all of
+		 * shared buffers.  We assume the caller who allocated the memory for
+		 * the BufferAccessStrategy will free it.
+		 */
+		vacrel->bstrategy = NULL;
+
 		/* Disable index vacuuming, index cleanup, and heap rel truncation */
 		vacrel->do_index_vacuuming = false;
 		vacrel->do_index_cleanup = false;
 
@@ -391,11 +391,13 @@ vacuum(List *relations, VacuumParams *params,
 
 	/*
 	 * If caller didn't give us a buffer strategy object, make one in the
-	 * cross-transaction memory context.
+	 * cross-transaction memory context.  We needn't bother making this for
+	 * VACUUM (FULL) or VACUUM (ONLY_DATABASE_STATS) as they'll not make use
+	 * of it.
 	 */
 	if (bstrategy == NULL &&
-		!(params->options & VACOPT_ONLY_DATABASE_STATS ||
-		  params->options & VACOPT_FULL))
+		(params->options & (VACOPT_ONLY_DATABASE_STATS |
+							VACOPT_FULL)) == 0)
 	{
 		MemoryContext old_context = MemoryContextSwitchTo(vac_context);