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Tue, 24 Mar 2026 23:04:15 -0700 (PDT) Received: from laurenz.albe-K4N0CV00F97414D ([2001:871:270:4fd5:603f:45c2:9807:c104]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-43b6470f902sm46864413f8f.28.2026.03.24.23.04.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 24 Mar 2026 23:04:15 -0700 (PDT) Message-ID: <9960ee435fe72e3058de77bd28894daaff24031a.camel@cybertec.at> Subject: Re: AW: Replication Testing- How to introduce a Lag From: Laurenz Albe To: "Subramanian,Ramachandran" , "pgsql-novice@lists.postgresql.org" Date: Wed, 25 Mar 2026 07:04:14 +0100 In-Reply-To: <003a3038c353448cb2b7cf0e1a179f98@alte-leipziger.de> References: <8b38fa5141905f9ad6983b8d5ae944e812e3d28a.camel@cybertec.at> <0e00fcc0062b59b88f98dba4900ce49d5a9a3fea.camel@cybertec.at> <477369bf897b44feb2d2368f6fca93fc@alte-leipziger.de> <89d63402747edb3bf80ff668fdd63cc77334f446.camel@cybertec.at> <013104103e016e84d59c1e2accb0b1b1f99d9870.camel@cybertec.at> <39ec6185a893473aa9217520e5a92be7@alte-leipziger.de> <2fb6a2f5eb2c9a1cbe701a237c74223d121ca918.camel@cybertec.at> <003a3038c353448cb2b7cf0e1a179f98@alte-leipziger.de> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.58.3 (3.58.3-1.fc43) MIME-Version: 1.0 List-Id: List-Help: List-Subscribe: List-Post: List-Owner: List-Archive: Archived-At: Precedence: bulk On Tue, 2026-03-24 at 17:01 +0000, Subramanian,Ramachandran wrote: > My question is , can the difference in LSN from this query approximated > to the amount of data that is yet to be transferred >=20 > select=C2=A0 pg_wal_lsn_diff(pg_current_wal_lsn(),replay_lsn) from pg_sta= t_replication That query measures the replication lag in bytes, that *is* the amount of d= ata. Problem solved! Yours, Laurenz Albe