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From: "David G. Johnston" <david.g.johnston@gmail.com>
Date: Tue, 4 Mar 2025 08:38:07 -0700
Message-ID: <CAKFQuwbzEDV2e4yfSpr8SkLyxEmAk=WPn3uo3C2q+1xR5VymVA@mail.gmail.com>
Subject: Re: Review my steps for rollback to restore point
To: chandan Kumar <chandan.issyoga@gmail.com>
Cc: Laurenz Albe <laurenz.albe@cybertec.at>, 
	"pgsql-general@lists.postgresql.org" <pgsql-general@lists.postgresql.org>
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On Tuesday, March 4, 2025, chandan Kumar <chandan.issyoga@gmail.com> wrote:

> Thank you for your time and clarification.
> Does PITR recreate database internally ?  can i say it is not the same as
> pg_restore  or it is same as pg_restore plus applying WAL on top of it.  =
I
> am asking because can we revern DDL operations without PITR in streaming
> replication
>

PostgreSQL doesn=E2=80=99t have a concept of =E2=80=9Crevert=E2=80=9D.

PITR just deals with raw bytes on disk for an entire cluster.  If a new
file appears in the WAL that file is created.  That file can be a directory
for a database.

You cannot mix physical and logical images of the database so applying WAL
on top of pg_restore is technically invalid - but it does effective convey
the idea.  It=E2=80=99s like saying pg_dump and pg_basebackup are similar. =
 Sure,
in some ways that is true - but the logical vs. physical distinction cannot
be ignored fully.

David J.

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On Tuesday, March 4, 2025, chandan Kumar &lt;<a href=3D"mailto:chandan.issy=
oga@gmail.com">chandan.issyoga@gmail.com</a>&gt; wrote:<br><blockquote clas=
s=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;pad=
ding-left:1ex"><div dir=3D"ltr">Thank you for your time and clarification.=
=C2=A0<div>Does PITR recreate database internally ?=C2=A0 can i say it is n=
ot the same as pg_restore=C2=A0 or it is same as pg_restore plus applying W=
AL on top of it.=C2=A0 I am asking because can we revern DDL operations wit=
hout PITR in streaming replication</div></div></blockquote><div><br></div><=
div>PostgreSQL doesn=E2=80=99t have a concept of =E2=80=9Crevert=E2=80=9D.<=
/div><div><br></div><div>PITR just deals with raw bytes on disk for an enti=
re cluster.=C2=A0 If a new file appears in the WAL that file is created.=C2=
=A0 That file can be a directory for a database.</div><div><br></div><div>Y=
ou cannot mix physical and logical images of the database so applying WAL o=
n top of pg_restore is technically invalid - but it does effective convey t=
he idea.=C2=A0 It=E2=80=99s like saying pg_dump and pg_basebackup are simil=
ar.=C2=A0 Sure, in some ways that is true - but the logical vs. physical di=
stinction cannot be ignored fully.</div><div><br></div><div>David J.</div><=
div><br></div>

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