diff --git a/src/backend/commands/dbcommands.c b/src/backend/commands/dbcommands.c
index 289310c59d4..17ef3a8b65b 100644
--- a/src/backend/commands/dbcommands.c
+++ b/src/backend/commands/dbcommands.c
@@ -1131,6 +1131,23 @@ movedb(const char *dbname, const char *tblspcname)
 	RequestCheckpoint(CHECKPOINT_IMMEDIATE | CHECKPOINT_FORCE | CHECKPOINT_WAIT
 					  | CHECKPOINT_FLUSH_ALL);
 
+	/*
+	 * Now drop all buffers holding data of the target database; they should
+	 * no longer be dirty so DropDatabaseBuffers is safe.
+	 *
+	 * It might seem that we could just let these buffers age out of shared
+	 * buffers naturally, since they should not get referenced anymore.  The
+	 * problem with that is that if the user later moves the database back to
+	 * its original tablespace, any still-surviving buffers would appear to
+	 * contain valid data again --- but they'd be missing any changes made in
+	 * the database while it was in the new tablespace.  In any case, freeing
+	 * buffers that should never be used again seems worth the cycles.
+	 *
+	 * Note: it'd be sufficient to get rid of buffers matching db_id and
+	 * src_tblspcoid, but bufmgr.c presently provides no API for that.
+	 */
+	DropDatabaseBuffers(db_id);
+
 	/*
 	 * Check for existence of files in the target directory, i.e., objects of
 	 * this database that are already in the target tablespace.  We can't