database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-07-08 11:42:09 +03:00
Code Activity

HOT updates. When we update a tuple without changing any of its indexed

Browse Source 
columns, and the new version can be stored on the same heap page, we no longer
generate extra index entries for the new version.  Instead, index searches
follow the HOT-chain links to ensure they find the correct tuple version.

In addition, this patch introduces the ability to "prune" dead tuples on a
per-page basis, without having to do a complete VACUUM pass to recover space.
VACUUM is still needed to clean up dead index entries, however.

Pavan Deolasee, with help from a bunch of other people.
This commit is contained in:
Tom Lane
2007-09-20 17:56:33 +00:00
parent bbf4fdc253
commit 282d2a03dd
65 changed files with 3517 additions and 514 deletions
Download Patch File Download Diff File Expand all files Collapse all files

8
src/backend/access/heap/rewriteheap.c
View File

@ -96,7 +96,7 @@
* Portions Copyright (c) 1994-5, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/access/heap/rewriteheap.c,v 1.6 2007/09/12 22:10:26 tgl Exp $
* $PostgreSQL: pgsql/src/backend/access/heap/rewriteheap.c,v 1.7 2007/09/20 17:56:30 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -320,12 +320,14 @@ rewrite_heap_tuple(RewriteState state,
* Copy the original tuple's visibility information into new_tuple.
*
* XXX we might later need to copy some t_infomask2 bits, too?
* Right now, we intentionally clear the HOT status bits.
*/
memcpy(&new_tuple->t_data->t_choice.t_heap,
&old_tuple->t_data->t_choice.t_heap,
sizeof(HeapTupleFields));
new_tuple->t_data->t_infomask &= ~HEAP_XACT_MASK;
new_tuple->t_data->t_infomask2 &= ~HEAP2_XACT_MASK;
new_tuple->t_data->t_infomask |=
old_tuple->t_data->t_infomask & HEAP_XACT_MASK;
@ -593,7 +595,7 @@ raw_heap_insert(RewriteState state, HeapTuple tup)
/* Now we can check to see if there's enough free space already. */
if (state->rs_buffer_valid)
{
pageFreeSpace = PageGetFreeSpace(page);
pageFreeSpace = PageGetHeapFreeSpace(page);
if (len + saveFreeSpace > pageFreeSpace)
{
@ -628,7 +630,7 @@ raw_heap_insert(RewriteState state, HeapTuple tup)
/* And now we can insert the tuple into the page */
newoff = PageAddItem(page, (Item) heaptup->t_data, len,
InvalidOffsetNumber, false);
InvalidOffsetNumber, false, true);
if (newoff == InvalidOffsetNumber)
elog(ERROR, "failed to add tuple");