diff options
Diffstat (limited to 'src/backend/access/transam/xlog.c')
| -rw-r--r-- | src/backend/access/transam/xlog.c | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c index b0556034aeb..ba029397f87 100644 --- a/src/backend/access/transam/xlog.c +++ b/src/backend/access/transam/xlog.c @@ -7,7 +7,7 @@ * Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * - * $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.251 2006/10/06 17:13:58 petere Exp $ + * $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.252 2006/10/18 22:44:11 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -5807,6 +5807,16 @@ XLogPutNextOid(Oid nextOid) * record. Therefore, the standard buffer LSN interlock applied to those * records will ensure no such OID reaches disk before the NEXTOID record * does. + * + * Note, however, that the above statement only covers state "within" the + * database. When we use a generated OID as a file or directory name, + * we are in a sense violating the basic WAL rule, because that filesystem + * change may reach disk before the NEXTOID WAL record does. The impact + * of this is that if a database crash occurs immediately afterward, + * we might after restart re-generate the same OID and find that it + * conflicts with the leftover file or directory. But since for safety's + * sake we always loop until finding a nonconflicting filename, this poses + * no real problem in practice. See pgsql-hackers discussion 27-Sep-2006. */ } |