Re: PATCH: logical_work_mem and logical streaming of large in-progress transactions

On Wed, Nov 6, 2019 at 11:33 AM vignesh C <vignesh21(at)gmail(dot)com> wrote:
>
> I have made one change to the configuration file in
> contrib/test_decoding directory, with that the coverage seems to be
> fine. I have seen that the coverage is almost like the code before
> applying the patch. I have attached the test change and the coverage
> report for reference. Coverage report includes the core logical work
> memory files for base code and by applying
> 0001-Add-logical_decoding_work_mem-to-limit-ReorderBuffer and
> 0002-Track-statistics-for-spilling patches.
>

Thanks, I have incorporated your test changes and modified the two
patches. Please see attached.

Changes:
---------------
1. In guc.c, we should include reorderbuffer.h, not logical.h as we
define logical_decoding_work_mem in earlier.

2.
+ * To limit the amount of memory used by decoded changes, we track memory
+ * used at the reorder buffer level (i.e. total amount of memory), and for
+ * each toplevel transaction. When the total amount of used memory exceeds
+ * the limit, the toplevel transaction consuming the most memory is then
+ * serialized to disk.

In the above comments, removed 'toplevel' as we track memory usage for
both toplevel and subtransactions.

3. There were still a few mentions of streaming which I have removed.

4. In the docs, the type for stats spill_* was integer whereas it
should be bigint.

5.
+UpdateSpillStats(LogicalDecodingContext *ctx)
+{
+ ReorderBuffer *rb = ctx->reorder;
+
+ SpinLockAcquire(&MyWalSnd->mutex);
+
+ MyWalSnd->spillTxns = rb->spillTxns;
+ MyWalSnd->spillCount = rb->spillCount;
+ MyWalSnd->spillBytes = rb->spillBytes;
+
+ elog(WARNING, "UpdateSpillStats: updating stats %p %ld %ld %ld",
+ rb, rb->spillTxns, rb->spillCount, rb->spillBytes);

Changed the above elog to DEBUG1 as otherwise it was getting printed
very frequently. I think we can make it DEBUG2 if we want.

6. There was an extra space in rules.out due to which test was
failing. I have fixed it.

What do you think?

--
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com