postgres.git / summary / log / commit / refs

commit    a85045cccb1b7a6e4b60a9b13abdfb5574eafae5
Author:   Alvaro Herrera <alvherre@alvh.no-ip.org>
Date:     Thu Dec 27 19:00:39 2018 +0000
First released in: 9.4.21, 9.5.16, 9.6.12, 10.7

    Make autovacuum more selective about temp tables to keep
    
    When temp tables are in danger of XID wraparound, autovacuum drops them;
    however, it preserves those that are owned by a working session.  This
    is desirable, except when the session is connected to a different
    database (because the temp tables cannot be from that session), so make
    it only keep the temp tables only if the backend is in the same database
    as the temp tables.
    
    This is not bulletproof: it fails to detect temp tables left by a
    session whose backend ID is reused in the same database but the new
    session does not use temp tables.  Commit 943576bddcb5 fixes that case
    too, for branches 11 and up (which is why we don't apply this fix to
    those branches), but back-patching that one is not universally agreed
    on.
    
    Discussion: https://postgr.es/m/20181214162843.37g6h3txto43akrb@alvherre.pgsql
    Reviewed-by: Takayuki Tsunakawa, Michaël Paquier


 src/backend/postmaster/autovacuum.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/src/backend/postmaster/autovacuum.c b/src/backend/postmaster/autovacuum.c
index c49f1624b4c..a580a3c4924 100644
--- a/src/backend/postmaster/autovacuum.c
+++ b/src/backend/postmaster/autovacuum.c
@@ -2052,11 +2052,18 @@ do_autovacuum(void)
 		if (classForm->relpersistence == RELPERSISTENCE_TEMP)
 		{
 			int			backendID;
+			PGPROC	   *proc;
 
 			backendID = GetTempNamespaceBackendId(classForm->relnamespace);
 
-			/* We just ignore it if the owning backend is still active */
-			if (backendID == MyBackendId || BackendIdGetProc(backendID) == NULL)
+			/*
+			 * We just ignore it if the owning backend is still active in the
+			 * same database.
+			 */
+			if (backendID != InvalidBackendId &&
+				(backendID == MyBackendId ||
+				 (proc = BackendIdGetProc(backendID)) == NULL ||
+				 proc->databaseId != MyDatabaseId))
 			{
 				/*
 				 * We found an orphan temp table (which was probably left


[parent: 0a323ae67699]