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To support external compression of archived WAL data, add a flag bit to

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WAL records that shows whether it is safe to remove full-page images
(ie, whether or not an on-line backup was in progress when the WAL entry
was made).  Also make provision for an XLOG_NOOP record type that can be
used to fill in the extra space when decompressing the data for restore.

This is the portion of Koichi Suzuki's "full page writes" patch that
has to go into the core database.  The remainder of that work is two
external compression and decompression programs, which for the time being
will undergo separate development on pgfoundry.  Per discussion.

Also, twiddle the handling of BTREE_SPLIT records to ensure it'll be
possible to compress them (the previous coding caused essential info
to be omitted).  The other commonly-used record types seem OK already,
with the possible exception of GIN and GIST WAL records, which I don't
understand well enough to opine on.
This commit is contained in:
Tom Lane
2007-05-20 21:08:19 +00:00
parent 2f2717d14f
commit a8d539f124
6 changed files with 53 additions and 17 deletions
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15
src/backend/access/nbtree/nbtinsert.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/access/nbtree/nbtinsert.c,v 1.156 2007/04/11 20:47:37 tgl Exp $
* $PostgreSQL: pgsql/src/backend/access/nbtree/nbtinsert.c,v 1.157 2007/05/20 21:08:19 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -1034,21 +1034,23 @@ _bt_split(Relation rel, Buffer buf, OffsetNumber firstright,
* Log the new item and its offset, if it was inserted on the left
* page. (If it was put on the right page, we don't need to explicitly
* WAL log it because it's included with all the other items on the
* right page.) Show these as belonging to the left page buffer,
* so that they are not stored if XLogInsert decides it needs a
* full-page image of the left page.
* right page.) Show the new item as belonging to the left page buffer,
* so that it is not stored if XLogInsert decides it needs a full-page
* image of the left page. We store the offset anyway, though, to
* support archive compression of these records.
*/
if (newitemonleft)
{
lastrdata->next = lastrdata + 1;
lastrdata++;
lastrdata->data = (char *) &newitemoff;
lastrdata->len = sizeof(OffsetNumber);
lastrdata->buffer = buf; /* backup block 1 */
lastrdata->buffer_std = true;
lastrdata->buffer = InvalidBuffer;
lastrdata->next = lastrdata + 1;
lastrdata++;
lastrdata->data = (char *) newitem;
lastrdata->len = MAXALIGN(newitemsz);
lastrdata->buffer = buf; /* backup block 1 */
@ -1064,6 +1066,7 @@ _bt_split(Relation rel, Buffer buf, OffsetNumber firstright,
*/
lastrdata->next = lastrdata + 1;
lastrdata++;
lastrdata->data = NULL;
lastrdata->len = 0;
lastrdata->buffer = buf; /* backup block 1 */