database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-09-02 04:21:28 +03:00
Code Activity

Combine freezing and pruning steps in VACUUM

Browse Source 
Execute both freezing and pruning of tuples in the same
heap_page_prune() function, now called heap_page_prune_and_freeze(),
and emit a single WAL record containing all changes. That reduces the
overall amount of WAL generated.

This moves the freezing logic from vacuumlazy.c to the
heap_page_prune_and_freeze() function. The main difference in the
coding is that in vacuumlazy.c, we looked at the tuples after the
pruning had already happened, but in heap_page_prune_and_freeze() we
operate on the tuples before pruning. The heap_prepare_freeze_tuple()
function is now invoked after we have determined that a tuple is not
going to be pruned away.

VACUUM no longer needs to loop through the items on the page after
pruning. heap_page_prune_and_freeze() does all the work. It now
returns the list of dead offsets, including existing LP_DEAD items, to
the caller. Similarly it's now responsible for tracking 'all_visible',
'all_frozen', and 'hastup' on the caller's behalf.

Author: Melanie Plageman <melanieplageman@gmail.com>
Discussion: https://www.postgresql.org/message-id/20240330055710.kqg6ii2cdojsxgje@liskov
This commit is contained in:
Heikki Linnakangas
2024-04-03 19:32:28 +03:00
parent 26d138f644
commit 6dbb490261
7 changed files with 813 additions and 545 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
src/backend/storage/ipc/procarray.c
View File

@@ -1715,9 +1715,9 @@ TransactionIdIsActive(TransactionId xid)
* Note: the approximate horizons (see definition of GlobalVisState) are
* updated by the computations done here. That's currently required for
* correctness and a small optimization. Without doing so it's possible that
* heap vacuum's call to heap_page_prune() uses a more conservative horizon
* than later when deciding which tuples can be removed - which the code
* doesn't expect (breaking HOT).
* heap vacuum's call to heap_page_prune_and_freeze() uses a more conservative
* horizon than later when deciding which tuples can be removed - which the
* code doesn't expect (breaking HOT).
*/
static void
ComputeXidHorizons(ComputeXidHorizonsResult *h)