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authorAlvaro Herrera2014-11-28 21:06:18 +0000
committerAlvaro Herrera2014-11-28 21:07:04 +0000
commit0dafa9584e64243cb4d305be903623d6e709c584 (patch)
tree7d9a33e910dfa7633304c8b754bb5a72448c1fa1 /src/backend
parent4b1953079fb020da7089e58e3b0543058d867803 (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.
Diffstat (limited to 'src/backend')
-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 3a32471e951..82ffb98680f 100644
--- a/src/backend/access/transam/README
+++ b/src/backend/access/transam/README
@@ -812,10 +812,7 @@ 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