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authorAlvaro Herrera2014-11-28 21:06:18 +0000
committerAlvaro Herrera2014-11-28 21:06:18 +0000
commitae04bf50277ae25ca741cf3322d231c7dfb4c997 (patch)
tree2c93bfa97ff8090f25888216eb822c0a07b687fb
parentd25367ec4f869aac80e97964fa5d7143536818b1 (diff)
Update transaction README for persistent multixacts
Multixacts are now maintained during recovery, but the README didn't get the memo. Backpatch to 9.3, where the divergence was introduced.
-rw-r--r--src/backend/access/transam/README5
1 files changed, 1 insertions, 4 deletions
diff --git a/src/backend/access/transam/README b/src/backend/access/transam/README
index ba6ae05d65..b619de5ad3 100644
--- a/src/backend/access/transam/README
+++ b/src/backend/access/transam/README
@@ -840,10 +840,7 @@ parent transaction to complete.
Not all transactional behaviour is emulated, for example we do not insert
a transaction entry into the lock table, nor do we maintain the transaction
-stack in memory. Clog entries are made normally. Multixact is not maintained
-because its purpose is to record tuple level locks that an application has
-requested to prevent other tuple locks. Since tuple locks cannot be obtained at
-all, there is never any conflict and so there is no reason to update multixact.
+stack in memory. Clog and multixact entries are made normally.
Subtrans is maintained during recovery but the details of the transaction
tree are ignored and all subtransactions reference the top-level TransactionId
directly. Since commit is atomic this provides correct lock wait behaviour