v7-0010-Skip-VACUUM-ANALYZE-with-VACOPT_SKIP_LOCKED-if-ex.patch

From 2a38290b6ccc36d3d0389d833aed44b7d1ac6d64 Mon Sep 17 00:00:00 2001
From: Nathan Bossart <bossartn@amazon.com>
Date: Thu, 5 Apr 2018 18:52:11 +0000
Subject: [PATCH v7 10/12] Skip VACUUM/ANALYZE with VACOPT_SKIP_LOCKED if
 expand_vacuum_rel() would block.

---
 src/backend/commands/vacuum.c | 30 ++++++++++++++++++++++++++----
 1 file changed, 26 insertions(+), 4 deletions(-)

diff --git a/src/backend/commands/vacuum.c b/src/backend/commands/vacuum.c
index fb7dd8d536..f19d112af6 100644
--- a/src/backend/commands/vacuum.c
+++ b/src/backend/commands/vacuum.c
@@ -68,7 +68,7 @@ static BufferAccessStrategy vac_strategy;
 
 
 /* non-export function prototypes */
-static List *expand_vacuum_rel(VacuumRelation *vrel);
+static List *expand_vacuum_rel(VacuumRelation *vrel, int options);
 static List *get_all_vacuum_rels(void);
 static void vac_truncate_clog(TransactionId frozenXID,
 				  MultiXactId minMulti,
@@ -257,7 +257,7 @@ vacuum(int options, List *relations, VacuumParams *params,
 			List	   *sublist;
 			MemoryContext old_context;
 
-			sublist = expand_vacuum_rel(vrel);
+			sublist = expand_vacuum_rel(vrel, options);
 			old_context = MemoryContextSwitchTo(vac_context);
 			newrels = list_concat(newrels, sublist);
 			MemoryContextSwitchTo(old_context);
@@ -423,7 +423,7 @@ vacuum(int options, List *relations, VacuumParams *params,
  * are made in vac_context.
  */
 static List *
-expand_vacuum_rel(VacuumRelation *vrel)
+expand_vacuum_rel(VacuumRelation *vrel, int options)
 {
 	List	   *vacrels = NIL;
 	MemoryContext oldcontext;
@@ -454,7 +454,29 @@ expand_vacuum_rel(VacuumRelation *vrel)
 		 * below, as well as find_all_inheritors's expectation that the caller
 		 * holds some lock on the starting relation.
 		 */
-		relid = RangeVarGetRelid(vrel->relation, AccessShareLock, false);
+		relid = RangeVarGetRelidExtended(vrel->relation,
+										 AccessShareLock,
+										 (options & VACOPT_SKIP_LOCKED) ? RVR_SKIP_LOCKED : 0,
+										 NULL, NULL);
+
+		/*
+		 * If the lock is unavailable, emit the same log statement that
+		 * vacuum_rel() and analyze_rel() would.
+		 */
+		if (!OidIsValid(relid))
+		{
+			if (options & VACOPT_VACUUM)
+				ereport(WARNING,
+						(errcode(ERRCODE_LOCK_NOT_AVAILABLE),
+						 errmsg("skipping vacuum of \"%s\" --- lock not available",
+								vrel->relation->relname)));
+			else
+				ereport(WARNING,
+						(errcode(ERRCODE_LOCK_NOT_AVAILABLE),
+						 errmsg("skipping analyze of \"%s\" --- lock not available",
+								vrel->relation->relname)));
+			return vacrels;
+		}
 
 		/*
 		 * Make a returnable VacuumRelation for this rel.
-- 
2.16.2