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 <060c8abd-7448-4af9-8265-0ca8b81ccf86@aklaver.com>
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From: veem v <veema0000@gmail.com>
Date: Thu, 15 May 2025 21:59:26 +0530
Message-ID: <CAB+=1TV7J-ORtH8EtbuqbheLdSRsw4YBh+Cw38X5cfRbQsTUnQ@mail.gmail.com>
Subject: Re: How to have a smooth migration
To: Adrian Klaver <adrian.klaver@aklaver.com>, "Peter J. Holzer" <hjp-pgsql@hjp.at>
Cc: pgsql-general <pgsql-general@lists.postgresql.org>
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>
>
>
> This is what Sqitch(https://sqitch.org/) was designed for.
>
> The biggest issue is that the data will be incrementing while you do the
> structural changes. How you handle that is going to depend on the
> question raised by Peter J. Holzer:
> Is this  being done in place on one Postgres instance or between
> separate Postgres instances?
>
>
>
Thank you. Yes, these tables are going to be part of the same database.
Never use sqitch though , but was wondering if we can do it with the stored
simple proc as the number of table is very small <20 and also the max size
of table in <50MB. Also , missed to add , this is a cloud RDS database and
so not sure we can have this tool there.

To answer the questions specifically raised by Peter J. Holzer .


*Are V1 and V2 different databases or do plan to do this in-place?*Answer:-
Yes both the versions of the table are in the same database.

*What is the purpose of doing it in multiple phases? Do you have lengthy
acceptance tests during which new data will accumulate?*
Answer:-
Yes. Actually there will be a test kind of thing happen with the new code
pointing to version V2 tables and to get comfortable. But teh delta data
will  be very small.


*By "rollback" do mean a transaction rollback or some other means of
restoring the previous state?*Answer:-
"rollbak" means pointing the old code back to the version V1 tables.

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<div dir=3D"ltr"><div class=3D"gmail_quote gmail_quote_container"><blockquo=
te class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px =
solid rgb(204,204,204);padding-left:1ex"><br><br>
This is what Sqitch(<a href=3D"https://sqitch.org/" rel=3D"noreferrer" targ=
et=3D"_blank">https://sqitch.org/</a>) was designed for.<br>
<br>
The biggest issue is that the data will be incrementing while you do the <b=
r>
structural changes. How you handle that is going to depend on the <br>
question raised by Peter J. Holzer:<br>
Is this=C2=A0 being done in place on one Postgres instance or between <br>
separate Postgres instances?<br><br>
<br></blockquote><div><br></div><div>Thank you. Yes, these tables are going=
 to be part of the same database. Never use sqitch though , but was wonderi=
ng if we can do it with the stored simple proc as the number of table is ve=
ry small &lt;20 and also the max size of table in &lt;50MB. Also , missed t=
o add , this is a cloud RDS database and so not sure we can have this tool =
there.</div><div><br></div><div>To answer the questions specifically raised=
 by Peter J. Holzer .</div><div><br></div><div><i>Are V1 and V2 different d=
atabases or do plan to do this in-place?<br></i>Answer:-<br>Yes both the ve=
rsions of the table are in the same database.<br><br><i>What is the purpose=
 of doing it in multiple phases? Do you have lengthy acceptance tests durin=
g which new data will accumulate?</i><br>Answer:-<br>Yes. Actually there wi=
ll be a test kind of thing happen with the new code pointing to version V2 =
tables and to get comfortable. But teh delta data will =C2=A0be very small.=
<br><br><i>By &quot;rollback&quot; do mean a transaction rollback or some o=
ther means of restoring the previous state?<br></i>Answer:-<br>&quot;rollba=
k&quot; means pointing the old code back to the version V1 tables.</div><di=
v>=C2=A0</div></div></div>

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