From 8af186ee9dd8c7dc20f37a69b34cab7b95faa43b Mon Sep 17 00:00:00 2001 From: Heikki Linnakangas Date: Wed, 20 Mar 2024 14:03:06 +0200 Subject: [PATCH v5 07/26] Add comment to log_heap_prune_and_freeze(). XXX: This should be rewritten, but I tried to at least list some important points. --- src/backend/access/heap/pruneheap.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/src/backend/access/heap/pruneheap.c b/src/backend/access/heap/pruneheap.c index 6482d9d05c1..cd86a6262f5 100644 --- a/src/backend/access/heap/pruneheap.c +++ b/src/backend/access/heap/pruneheap.c @@ -1274,6 +1274,25 @@ heap_log_freeze_plan(HeapTupleFreeze *tuples, int ntuples, return nplans; } +/* + * Write a XLOG_HEAP2_PRUNE_FREEZE WAL record + * + * This is used for several different page maintenance operations: + * + * Page pruning: some items are redirected, some marked dead, some removed altogether + * + * Freezing: only 'frozen' is used + * + * Vacuum, 2nd pass: only 'unused' is used, and lp_truncate_only is set to true. + * + * They have enough commonalities that we use a single WAL record for them + * all. + * + * Note: This function scribbles on the 'frozen' array. + * + * The caller must hold an appropriate lock on 'buffer'. + * Note: This is called in a critical section, so careful what you do here. + */ void log_heap_prune_and_freeze(Relation relation, Buffer buffer, TransactionId conflict_xid, -- 2.39.2