diff options
Diffstat (limited to 'src/db/db_meta.c')
| -rw-r--r-- | src/db/db_meta.c | 16 |
1 files changed, 9 insertions, 7 deletions
diff --git a/src/db/db_meta.c b/src/db/db_meta.c index 8f97ebd8..53cf77cc 100644 --- a/src/db/db_meta.c +++ b/src/db/db_meta.c @@ -1,7 +1,7 @@ /*- * See the file LICENSE for redistribution information. * - * Copyright (c) 1996, 2012 Oracle and/or its affiliates. All rights reserved. + * Copyright (c) 1996, 2015 Oracle and/or its affiliates. All rights reserved. */ /* * Copyright (c) 1990, 1993, 1994, 1995, 1996 @@ -939,12 +939,14 @@ done: if (last_pgnop != NULL) *last_pgnop = meta->last_pgno; /* - * The truncate point is the number of pages in the free - * list back from the last page. The number of pages - * in the free list are the number that we can swap in. - * Adjust it down slightly so if we find higher numbered - * pages early and then free other pages later we can - * truncate them. + * Set the truncation point which determines which pages may be + * relocated. Pages above are candidates to be swapped with a lower one + * from the freelist by __db_exchange_page(); pages before the truncate + * point are not relocated. + * The truncation point starts as N pages less than the last_pgno, where + * N is the size of the free list. This is reduced by 1/4 in the hope + * that partially full pages will be coalesced together, creating + * additional free pages during the compact. */ if (c_data) { c_data->compact_truncate = (u_int32_t)meta->last_pgno - nelems; |