Re: PATCH: logical_work_mem and logical streaming of large in-progress transactions
Amit Kapila <amit.kapila16@gmail.com>
Commits
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API reference →
-
Tighten the concurrent abort check during decoding.
- 2ce353fc1902 14.0 landed
-
Improve hash_create()'s API for some added robustness.
- b3817f5f7746 14.0 landed
-
Use HASH_BLOBS for xidhash.
- a1b8aa1e4eec 14.0 landed
-
Fix initialization of RelationSyncEntry for streaming transactions.
- 69bd60672af6 14.0 landed
-
Remove unused function declaration in logicalproto.h.
- ddd5f6d2609b 14.0 landed
-
Add additional tests to test streaming of in-progress transactions.
- 58b5ae9d62bd 14.0 landed
-
Fix inline marking introduced in commit 464824323e.
- ac15b499f7f9 14.0 landed
-
Add support for streaming to built-in logical replication.
- 464824323e57 14.0 landed
-
Fix the SharedFileSetUnregister API.
- 4ab77697f67a 14.0 landed
-
Fix comment in procarray.c
- 77c7267c37f7 14.0 cited
-
Suppress compiler warning in non-cassert builds.
- e942af7b8261 14.0 cited
-
Extend the BufFile interface.
- 808e13b282ef 14.0 landed
-
Mark a few logical decoding related variables with PGDLLIMPORT.
- b48cac3b10a0 14.0 landed
-
Implement streaming mode in ReorderBuffer.
- 7259736a6e5b 14.0 landed
-
Extend the logical decoding output plugin API with stream methods.
- 45fdc9738b36 14.0 landed
-
WAL Log invalidations at command end with wal_level=logical.
- c55040ccd017 14.0 landed
-
Immediately WAL-log subtransaction and top-level XID association.
- 0bead9af484c 14.0 landed
-
Allow logical replication to transfer data in binary format.
- 9de77b545313 14.0 cited
-
Only superuser can set sslcert/sslkey in postgres_fdw user mappings
- cebf9d6e6ee1 13.0 cited
-
Track statistics for spilling of changes from ReorderBuffer.
- 9290ad198b15 13.0 landed
-
Add logical_decoding_work_mem to limit ReorderBuffer memory usage.
- cec2edfa7859 13.0 landed
-
logical decoding: process ASSIGNMENT during snapshot build
- bac2fae05c77 13.0 cited
-
Emit invalidations to standby for transactions without xid.
- c6ff84b06a68 9.6.0 cited
On Thu, Nov 14, 2019 at 3:40 PM Dilip Kumar <dilipbalaut@gmail.com> wrote:
>
>
> Apart from this, I have another question in
> 0003-Issue-individual-invalidations-with-wal_level-logical.patch
>
> @@ -543,6 +588,18 @@ RegisterSnapshotInvalidation(Oid dbId, Oid relId)
> {
> AddSnapshotInvalidationMessage(&transInvalInfo->CurrentCmdInvalidMsgs,
> dbId, relId);
> +
> + /* Issue an invalidation WAL record (when wal_level=logical) */
> + if (XLogLogicalInfoActive())
> + {
> + SharedInvalidationMessage msg;
> +
> + msg.sn.id = SHAREDINVALSNAPSHOT_ID;
> + msg.sn.dbId = dbId;
> + msg.sn.relId = relId;
> +
> + LogLogicalInvalidations(1, &msg, false);
> + }
> }
>
> I am not sure why do we need to explicitly WAL log the snapshot
> invalidation? because this is logged for invalidating the catalog
> snapshot and for logical decoding we use HistoricSnapshot, not the
> catalog snapshot.
>
I think it has been logged because without this patch as well we log
all the invalidation messages at commit time and process them during
decoding. However, I agree that this particular invalidation message
is not required for logical decoding for the reason you mentioned. I
think as we are explicitly logging invalidations, so it is better to
avoid this if we can.
Few other comments on this patch:
1.
+ case REORDER_BUFFER_CHANGE_INVALIDATION:
+
+ /*
+ * Execute the invalidation message locally.
+ *
+ * XXX Do we need to care about relcacheInitFileInval and
+ * the other fields added to ReorderBufferChange, or just
+ * about the message itself?
+ */
+ LocalExecuteInvalidationMessage(&change->data.inval.msg);
+ break;
Here, why are we executing messages individually? Can't we just
follow what we do in DecodeCommit which is to record the invalidations
in ReorderBufferTXN as we encounter them and then allow them to
execute on each REORDER_BUFFER_CHANGE_INTERNAL_COMMAND_ID. Is there a
reason why we don't do ReorderBufferXidSetCatalogChanges when we
receive any invalidation message?
2.
@@ -3025,8 +3073,8 @@ ReorderBufferRestoreChange(ReorderBuffer *rb,
ReorderBufferTXN *txn,
* although we don't check the memory limit when restoring the changes in
* this branch (we only do that when initially queueing the changes after
* decoding), because we will release the changes later, and that will
- * update the accounting too (subtracting the size from the counters).
- * And we don't want to underflow there.
+ * update the accounting too (subtracting the size from the counters). And
+ * we don't want to underflow there.
*/
This seems like an unrelated change.
--
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com