On Tue, 30 Jan 2024, 05:02 Adrian Klaver, <adrian.kla...@aklaver.com> wrote:
> On 1/29/24 11:35, Shaheed Haque wrote: > > > > > > On Tue, 30 Jan 2024, 00:27 Adrian Klaver, <adrian.kla...@aklaver.com > > <mailto:adrian.kla...@aklaver.com>> wrote: > > > > On 1/29/24 10:12, Shaheed Haque wrote: > > > > > > > > > > Yes. But I was under the impression that the initial copy of > logical > > > replication was the same? > > > > > > > Are you taking about the copy_data option to WITH? > > > > If so yes and no. > > > > Yes as it uses COPY to transfer the data. > > > > > > Yes, this is what I meant. > > > > No as what COPY transfers can be affected by WHERE clauses on the > > publisher. Also if you have cascading publishers/subscriptions the > > 'original' data maybe upstream of the publisher you are comparing to. > > > > > > Good points, understood. For the next bit, let's assume neither of these > > are in play. > > > > Finally logical replication is generally not static so there is the > > issue of determining a point in time for the check. > > > > > > Indeed. I currently have a static source db but would eventually like to > > eliminate the implied downtime. What I'd like to provide my user is some > > Implied downtime of what? > Oh, forgot to say: the downtime of my Django based app. Not anything at the PG level. > > indication of progress initially during the copy_data phase, and for the > > future, of the anticipated incremental convergence. > > > > And, as per my other note, I would ideally like to be able to do this > > using only a connection to one db. > > > > I was assuming that logical replication needed "something" similar > > internally, and was hoping the LSNs were that "something". > > I'm going to say up front I am no expert on the internals of logical > replication. Will point you at: > > https://www.postgresql.org/docs/current/protocol-message-formats.html > > A quick look at that indicates to me it is more involved then you think. > > > > > Thanks, Shaheed > > > > > > -- > > Adrian Klaver > > adrian.kla...@aklaver.com <mailto:adrian.kla...@aklaver.com> > > > > -- > Adrian Klaver > adrian.kla...@aklaver.com > >
