User-Agent: Cyrus-JMAP/3.5.0-alpha0-1302-gc62ab821ef-fm-20210921.001-gc62ab821
Mime-Version: 1.0
Message-Id: <73b06a32-56ab-4056-86ff-e307f3c316f1@www.fastmail.com>
In-Reply-To: 
 <CAA4eK1KSBGrLKR63iS38Bkvjq6fBCWzbuD6R15kEWdmd8aj3mw@mail.gmail.com>
References: 
 <CAB-JLwYOYwL=XTyAXKiH5CtM_Vm8KjKh7aaitCKvmCh4rzr5pQ@mail.gmail.com>
 <CAA4eK1JW+_Pff3TOaBqbOqn-LbMT2kj2bpw-a88ZSTdbTZ-aMg@mail.gmail.com>
 <CAB-JLwas_=FGr8bXKD7K6g0=RDUFuYU71TLLGTsQ-DTRNpq1QQ@mail.gmail.com>
 <CAA4eK1KSBGrLKR63iS38Bkvjq6fBCWzbuD6R15kEWdmd8aj3mw@mail.gmail.com>
Date: Wed, 22 Sep 2021 13:57:29 -0300
From: "Euler Taveira" <euler@eulerto.com>
To: "Amit Kapila" <amit.kapila16@gmail.com>,
 "Marcos Pegoraro" <marcos@f10.com.br>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>
Subject: Re: logical replication restrictions
Content-Type: multipart/alternative;
 boundary=df050943fdad441089a6bce7f7f47ca7
Archived-At: 
 <https://www.postgresql.org/message-id/73b06a32-56ab-4056-86ff-e307f3c316f1%40www.fastmail.com>
Precedence: bulk

--df050943fdad441089a6bce7f7f47ca7
Content-Type: text/plain;charset=utf-8
Content-Transfer-Encoding: quoted-printable

On Wed, Sep 22, 2021, at 1:18 AM, Amit Kapila wrote:
> On Tue, Sep 21, 2021 at 4:21 PM Marcos Pegoraro <marcos@f10.com.br> wr=
ote:
>> No, I=C2=B4m talking about that configuration you can have on standby=
 servers
>> recovery_min_apply_delay =3D '8h'
>>=20
>=20
> oh okay, I think this can be useful in some cases where we want to avo=
id data loss similar to its use for physical standby. For example, if th=
e user has by mistake truncated the table (or deleted some required data=
) on the publisher, we can always it from the subscriber if we have such=
 a feature.
>=20
> Having said that, I am not sure if we can call it a restriction. It is=
 more of a TODO kind of thing. It doesn't sound advisable to me to keep =
growing the current Restrictions page [1].
It is a new feature. pglogical supports it and it is useful for delayed
secondary server and if, for some business reason, you have to delay whe=
n data
is available. There might be other use cases but these are the ones I re=
gularly
heard from customers.

BTW, I have a WIP patch for this feature. I didn't have enough time to p=
ost it
because it lacks documentation and tests. I'm planning to do it as soon =
as this
CF ends.


--
Euler Taveira
EDB   https://www.enterprisedb.com/

--df050943fdad441089a6bce7f7f47ca7
Content-Type: text/html;charset=utf-8
Content-Transfer-Encoding: quoted-printable

<!DOCTYPE html><html><head><title></title><style type=3D"text/css">p.Mso=
Normal,p.MsoNoSpacing{margin:0}</style></head><body><div>On Wed, Sep 22,=
 2021, at 1:18 AM, Amit Kapila wrote:<br></div><blockquote type=3D"cite"=
 id=3D"qt" style=3D""><div dir=3D"ltr"><div dir=3D"ltr">On Tue, Sep 21, =
2021 at 4:21 PM Marcos Pegoraro &lt;<a href=3D"mailto:marcos@f10.com.br"=
>marcos@f10.com.br</a>&gt; wrote:<br></div><div class=3D"qt-gmail_quote"=
><blockquote class=3D"qt-gmail_quote" style=3D"margin-top:0px;margin-rig=
ht:0px;margin-bottom:0px;margin-left:0.8ex;border-left-color:rgb(204, 20=
4, 204);border-left-style:solid;border-left-width:1px;padding-left:1ex;"=
><div dir=3D"ltr"><div style=3D"font-family:verdana, sans-serif;color:rg=
b(102, 102, 102);">No, I=C2=B4m talking about that configuration you can=
 have on standby servers<br></div><div style=3D"font-family:verdana, san=
s-serif;color:rgb(102, 102, 102);">recovery_min_apply_delay =3D '8h'<br>=
</div><div><div dir=3D"ltr"><div dir=3D"ltr"><div><div dir=3D"ltr"><div>=
<div dir=3D"ltr"><br></div></div></div></div></div></div></div></div></b=
lockquote><div><br></div><div>oh okay, I think this can be useful in som=
e cases where we want to avoid data loss similar to its use for physical=
 standby. For example, if the user has by mistake&nbsp;truncated the tab=
le (or deleted some required data) on the publisher, we can always it fr=
om&nbsp;the&nbsp;subscriber if we have such a feature.<br></div><div><br=
></div><div>Having said that, I am not sure if we can call it a restrict=
ion. It is more of a TODO kind of thing. It doesn't sound advisable to m=
e to keep growing the current Restrictions page [1].<br></div></div></di=
v></blockquote><div>It is a new feature. pglogical supports it and it is=
 useful for delayed<br></div><div>secondary server and if, for some busi=
ness reason, you have to delay when data<br></div><div>is available. The=
re might be other use cases but these are the ones I regularly<br></div>=
<div>heard from customers.<br></div><div><br></div><div>BTW, I have a WI=
P patch for this feature. I didn't have enough time to post it<br></div>=
<div>because it lacks documentation and tests. I'm planning to do it as =
soon as this<br></div><div>CF ends.<br></div><div><br></div><div><br></d=
iv><div id=3D"sig112409080"><div class=3D"signature">--<br></div><div cl=
ass=3D"signature">Euler Taveira<br></div><div class=3D"signature">EDB&nb=
sp;&nbsp; <a href=3D"https://www.enterprisedb.com/">https://www.enterpri=
sedb.com/</a><br></div></div><div><br></div></body></html>
--df050943fdad441089a6bce7f7f47ca7--