Flush unlogged table's buffers when copying or moving databases.

CREATE DATABASE and ALTER DATABASE .. SET TABLESPACE copy the source
database directory on the filesystem level. To ensure the on disk
state is consistent they block out users of the affected database and
force a checkpoint to flush out all data to disk. Unfortunately, up to
now, that checkpoint didn't flush out dirty buffers from unlogged
relations.

That bug means there could be leftover dirty buffers in either the
template database, or the database in its old location. Leading to
problems when accessing relations in an inconsistent state; and to
possible problems during shutdown in the SET TABLESPACE case because
buffers belonging files that don't exist anymore are flushed.

This was reported in bug #10675 by Maxim Boguk.

Fix by Pavan Deolasee, modified somewhat by me. Reviewed by MauMau and
Fujii Masao.

Backpatch to 9.1 where unlogged tables were introduced.

1 files changed, 15 insertions, 11 deletions

diff --git a/src/backend/commands/dbcommands.c b/src/backend/commands/dbcommands.c
index b52e6b9bc07..1c56b4de0d2 100644
--- a/src/backend/commands/dbcommands.c
+++ b/src/backend/commands/dbcommands.c
@@ -549,15 +549,17 @@ createdb(const CreatedbStmt *stmt)
 	InvokeObjectPostCreateHook(DatabaseRelationId, dboid, 0);
 
 	/*
-	 * Force a checkpoint before starting the copy. This will force dirty
-	 * buffers out to disk, to ensure source database is up-to-date on disk
-	 * for the copy. FlushDatabaseBuffers() would suffice for that, but we
-	 * also want to process any pending unlink requests. Otherwise, if a
-	 * checkpoint happened while we're copying files, a file might be deleted
-	 * just when we're about to copy it, causing the lstat() call in copydir()
-	 * to fail with ENOENT.
+	 * Force a checkpoint before starting the copy. This will force all dirty
+	 * buffers, including those of unlogged tables, out to disk, to ensure
+	 * source database is up-to-date on disk for the copy.
+	 * FlushDatabaseBuffers() would suffice for that, but we also want
+	 * to process any pending unlink requests. Otherwise, if a checkpoint
+	 * happened while we're copying files, a file might be deleted just when
+	 * we're about to copy it, causing the lstat() call in copydir() to fail
+	 * with ENOENT.
 	 */
-	RequestCheckpoint(CHECKPOINT_IMMEDIATE | CHECKPOINT_FORCE | CHECKPOINT_WAIT);
+	RequestCheckpoint(CHECKPOINT_IMMEDIATE | CHECKPOINT_FORCE | CHECKPOINT_WAIT
+					  | CHECKPOINT_FLUSH_ALL);
 
 	/*
 	 * Once we start copying subdirectories, we need to be able to clean 'em
@@ -1138,8 +1140,9 @@ movedb(const char *dbname, const char *tblspcname)
 	dst_dbpath = GetDatabasePath(db_id, dst_tblspcoid);
 
 	/*
-	 * Force a checkpoint before proceeding. This will force dirty buffers out
-	 * to disk, to ensure source database is up-to-date on disk for the copy.
+	 * Force a checkpoint before proceeding. This will force all dirty
+	 * buffers, including those of unlogged tables, out to disk, to ensure
+	 * source database is up-to-date on disk for the copy.
 	 * FlushDatabaseBuffers() would suffice for that, but we also want to
 	 * process any pending unlink requests. Otherwise, the check for existing
 	 * files in the target directory might fail unnecessarily, not to mention
@@ -1147,7 +1150,8 @@ movedb(const char *dbname, const char *tblspcname)
 	 * On Windows, this also ensures that background procs don't hold any open
 	 * files, which would cause rmdir() to fail.
 	 */
-	RequestCheckpoint(CHECKPOINT_IMMEDIATE | CHECKPOINT_FORCE | CHECKPOINT_WAIT);
+	RequestCheckpoint(CHECKPOINT_IMMEDIATE | CHECKPOINT_FORCE | CHECKPOINT_WAIT
+					  | CHECKPOINT_FLUSH_ALL);
 
 	/*
 	 * Check for existence of files in the target directory, i.e., objects of