MIME-Version: 1.0
References: <CAKna9VaJ_qHKBnw4O-VT3xGmzqThCuZ=LFXx-hPdw7E6RoqmeA@mail.gmail.com>
 <CAD=mzVUmXmkdvvMG30G1=D4Kq3WqnzGo=0ov9JnRCs1p=KJiTQ@mail.gmail.com>
 <CAKna9VZRc4+Vzbt6qPGMCauE84isPtz-wE_KX9AOt7WKfhwjiQ@mail.gmail.com>
 <CAD=mzVUX13ZM16kP4QhY+F5XiLr=ezCXftKOTKA4eUvhphgOJw@mail.gmail.com>
 <CAKna9Vb_mx+dX02XOV6mpr8RFC-5io38kM6=4xRHQj_MUvQ+aQ@mail.gmail.com>
 <CAKAnmmJ6fqyYafLB_im75oxxfTuCLUY0ftBPU57pUm0g+pm6FQ@mail.gmail.com>
 <CAKna9VZJ4fginFJZenGQxWs9eAw9Z8g-YkdnOFcie5RvuJ=5OQ@mail.gmail.com>
 <CAKAnmmLv72uk1p8+zmWpkC+BTatrdmRe_NpRbwRsi1LAU-cJFQ@mail.gmail.com>
 <CAKna9VZGwtNx9NAZ0QjdT-WhtFETAaFzpUsvM6R90mjaAoP3vA@mail.gmail.com>
 <CAD=mzVVS6HbV25M7EA+TJYk22G=GJvQK5Gbe9eeifYSmadYtNA@mail.gmail.com>
 <CAKna9Vb0ABStAWogCsXK+jTT9ZuLESJ0_-r3Wtvd=rZpYMYwxw@mail.gmail.com>
 <CAKAnmm+_avfVEFGgADebEyH=oQrEDuvviOcMYNa+myjJrds8Eg@mail.gmail.com>
 <CAKna9Vahx4ow0mtTEbVSeAU+f6U9v6G+Dkr-ymoyNhUZF_GRWw@mail.gmail.com>
 <D8602AF7-7EDE-46EC-B12F-5AE003969994@gmail.com> <CAKna9VaO9adxGVebe6ySKV3QdH0ZR6N9ksnV==XOWtdT3uThtw@mail.gmail.com>
 <CAKna9VbVXcD7tR+1V08EJ0j8HVF+HwooZ3bPyiBKpxvg-ZQ3MQ@mail.gmail.com>
In-Reply-To: <CAKna9VbVXcD7tR+1V08EJ0j8HVF+HwooZ3bPyiBKpxvg-ZQ3MQ@mail.gmail.com>
From: Greg Sabino Mullane <htamfids@gmail.com>
Date: Sat, 17 Aug 2024 11:55:56 -0400
Message-ID: <CAKAnmmKjWVdPHUFVStspC_20XSp8bVSSJa4j3RXnHNPqtQJdfQ@mail.gmail.com>
Subject: Re: Column type modification in big tables
To: Lok P <loknath.73@gmail.com>
Cc: Alban Hertroys <haramrae@gmail.com>, sud <suds1434@gmail.com>, 
	pgsql-general <pgsql-general@lists.postgresql.org>
Content-Type: multipart/alternative; boundary="000000000000b92f3c061fe31e4a"
Archived-At: <https://www.postgresql.org/message-id/CAKAnmmKjWVdPHUFVStspC_20XSp8bVSSJa4j3RXnHNPqtQJdfQ%40mail.gmail.com>
Precedence: bulk

--000000000000b92f3c061fe31e4a
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

On Thu, Aug 15, 2024 at 4:41=E2=80=AFPM Lok P <loknath.73@gmail.com> wrote:

> Additionally , if we are okay with the 7.5hrs of down time , is my
> calculation/extrapolation of total time consumption based on a sample
> table,  for direct alter, accurate? Because, in that case , I was thinkin=
g
> it's less complex and also less error prone to just do it in a single alt=
er
> command rather than going for multiple steps of detach, alter, attach
> partition.
>

Well, it's meant to get you a ballpark figure, but yes, it seems as though
you will probably okay, But for something this critical involving
production downtime, I would try out the exact command and see how long it
takes on a test system. Restore a backup (you have backups I hope) or use
pg_basebackup to make a copy of your prod system somewhere.

Cheers,
Greg

--000000000000b92f3c061fe31e4a
Content-Type: text/html; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

<div dir=3D"ltr"><div dir=3D"ltr">On Thu, Aug 15, 2024 at 4:41=E2=80=AFPM L=
ok P &lt;<a href=3D"mailto:loknath.73@gmail.com">loknath.73@gmail.com</a>&g=
t; wrote:</div><div class=3D"gmail_quote"><blockquote class=3D"gmail_quote"=
 style=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);p=
adding-left:1ex"><div dir=3D"ltr"><div class=3D"gmail_quote"><div>Additiona=
lly , if we are okay with the 7.5hrs of down time , is my calculation/extra=
polation of total time consumption based on a sample table,=C2=A0 for direc=
t alter, accurate? Because, in that case , I was thinking it&#39;s less com=
plex and also less error prone to just do it in a single alter command rath=
er than going for multiple steps of detach, alter, attach partition.</div><=
/div></div></blockquote><div><br></div><div>Well, it&#39;s meant to get you=
 a ballpark figure, but yes, it seems as though you will probably okay, But=
 for something this critical involving production downtime, I would try out=
 the exact command and see how long it takes on a test system. Restore a ba=
ckup (you have backups I hope) or use pg_basebackup to make a copy of your =
prod system somewhere.</div><div><br></div><div>Cheers,</div><div>Greg</div=
><div><br></div><div><br></div><div><br></div><div><br></div><div>=C2=A0</d=
iv></div></div>

--000000000000b92f3c061fe31e4a--