Re: [HACKERS] logical decoding of two-phase transactions

On Tue, Dec 29, 2020 at 3:15 PM Ajin Cherian <itsajin(at)gmail(dot)com> wrote:
>
> Hi Sawada-san,
>
> I think Amit has a plan to commit this patch-set in phases. I will
> leave it to him to decide because I think he has a plan.
> I took time to refactor the test_decoding isolation test for
> consistent snapshot so that it uses just 3 sessions rather than 4.
> Posting an updated patch-0009
>

I have reviewed this test case patch and have the below comments:

1.
+step "s1checkpoint" { CHECKPOINT; }
...
+step "s2alter" { ALTER TABLE do_write ADD COLUMN addedbys2 int; }

I don't see the need for the above steps and we should be able to
generate the required scenario without these as well. Is there any
reason to keep those?

2.
"s3c""s1insert"

space is missing between these two.

3.
+# Force building of a consistent snapshot between a PREPARE and
COMMIT PREPARED.
+# Ensure that the whole transaction is decoded fresh at the time of
COMMIT PREPARED.
+permutation "s2b" "s2txid" "s1init" "s3b" "s3txid" "s2alter" "s2c"
"s2b" "s2insert" "s2prepare" "s3c""s1insert" "s1checkpoint" "s1start"
"s2commit" "s1start"

I think we can update the above comments to indicate how and which
important steps help us to realize the required scenario. See
subxact_without_top.spec for reference.

4.
+step "s2c" { COMMIT; }
...
+step "s2prepare" { PREPARE TRANSACTION 'test1'; }
+step "s2commit" { COMMIT PREPARED 'test1'; }

s2c and s2commit seem to be confusing names as both sounds like doing
the same thing. How about changing s2commit to s2cp and s2prepare to
s2p?

--
With Regards,
Amit Kapila.