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Wed, 27 Aug 2025 05:13:22 -0700 (PDT) Received: from laurenz.albe-K4N0CV00F97414D ([88.116.133.170]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-afe49310e00sm1011009466b.85.2025.08.27.05.13.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 27 Aug 2025 05:13:21 -0700 (PDT) Message-ID: Subject: Re: Inaccurate statement about log shipping replication mode From: Laurenz Albe To: artem.gavrilov@percona.com, pgsql-docs@lists.postgresql.org Date: Wed, 27 Aug 2025 14:13:21 +0200 In-Reply-To: <568ff8638e011b2726d06a4b95124ec51ee1e5af.camel@cybertec.at> References: <175578964049.806.14564779365418625473@wrigleys.postgresql.org> <568ff8638e011b2726d06a4b95124ec51ee1e5af.camel@cybertec.at> Content-Type: multipart/mixed; boundary="=-sjHGzuuTD4vUuBnnXbey" User-Agent: Evolution 3.56.2 (3.56.2-1.fc42) MIME-Version: 1.0 List-Id: List-Help: List-Subscribe: List-Post: List-Owner: List-Archive: Archived-At: Precedence: bulk --=-sjHGzuuTD4vUuBnnXbey Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Mon, 2025-08-25 at 09:58 +0200, Laurenz Albe wrote: > On Thu, 2025-08-21 at 15:20 +0000, PG Doc comments form wrote: > > Page: https://www.postgresql.org/docs/17/warm-standby.html > >=20 > > The documentation page about Log-Shipping Standby Servers after describ= ing > > that there are file-based log shipping and record-based log shipping > > (streaming replication) states: "It should be noted that log shipping i= s > > asynchronous, i.e., the WAL records are shipped after transaction commi= t.". > > This statement is misleading because the same page includes a section a= bout > > configuring synchronous streaming replication. To avoid confusion, I th= ink > > it makes sense to specify that record-based log shipping can be configu= red > > as either asynchronous or synchronous. >=20 > I think that the statement you quote is not only misleading, but wrong. > WAL can get shipped before the transaction commits. Perhaps the sentence > had better be >=20 > It should be noted that by default, log shipping is asynchronous, i.e., > the primary server does not wait until the standby receives the data. Here is a patch for that. Yours, Laurenz Albe --=-sjHGzuuTD4vUuBnnXbey Content-Disposition: attachment; filename="v1-0001-Fix-doc-defining-asynchronous-replication.patch" Content-Transfer-Encoding: base64 Content-Type: text/x-patch; name="v1-0001-Fix-doc-defining-asynchronous-replication.patch"; charset="UTF-8" RnJvbSA5N2NiOWE0ZTM2YWMwMzVlMWRjYzEwOGRkNmQzNjAzMzg5OGNjZDM2IE1vbiBTZXAgMTcg MDA6MDA6MDAgMjAwMQpGcm9tOiBMYXVyZW56IEFsYmUgPGxhdXJlbnouYWxiZUBjeWJlcnRlYy5h dD4KRGF0ZTogV2VkLCAyNyBBdWcgMjAyNSAxNDoxMDo0MSArMDIwMApTdWJqZWN0OiBbUEFUQ0gg djFdIEZpeCBkb2MgZGVmaW5pbmcgYXN5bmNocm9ub3VzIHJlcGxpY2F0aW9uCgpUaGUgc3RhdGVt ZW50IHdhcyBmYWN0dWFsbHkgd3Jvbmc6IFdBTCByZWNvcmRzIGNhbiBnZXQgc2hpcHBlZAp0byB0 aGUgc3RhbmRieSBiZWZvcmUgdGhlIHRyYW5zYWN0aW9uIGNvbW1pdHMuICBUaGUga2V5IHBvaW50 CmlzIHRoYXQgdGhlIHByaW1hcnkgZG9lcyBub3Qgd2FpdCBmb3IgdGhlIHN0YW5kYnkuCgpBdXRo b3I6IExhdXJlbnogQWxiZSA8bGF1cmVuei5hbGJlQGN5YmVydGVjLmF0PgpEaXNjdXNzaW9uOiBo dHRwczovL3Bvc3Rnci5lcy9tLzE3NTU3ODk2NDA0OS44MDYuMTQ1NjQ3NzkzNjU0MTg2MjU0NzNA d3JpZ2xleXMucG9zdGdyZXNxbC5vcmcKLS0tCiBkb2Mvc3JjL3NnbWwvaGlnaC1hdmFpbGFiaWxp dHkuc2dtbCB8IDQgKystLQogMSBmaWxlIGNoYW5nZWQsIDIgaW5zZXJ0aW9ucygrKSwgMiBkZWxl dGlvbnMoLSkKCmRpZmYgLS1naXQgYS9kb2Mvc3JjL3NnbWwvaGlnaC1hdmFpbGFiaWxpdHkuc2dt bCBiL2RvYy9zcmMvc2dtbC9oaWdoLWF2YWlsYWJpbGl0eS5zZ21sCmluZGV4IGI0N2Q4YjQxMDZl Li4zMzRiOGE0NjUyYSAxMDA2NDQKLS0tIGEvZG9jL3NyYy9zZ21sL2hpZ2gtYXZhaWxhYmlsaXR5 LnNnbWwKKysrIGIvZG9jL3NyYy9zZ21sL2hpZ2gtYXZhaWxhYmlsaXR5LnNnbWwKQEAgLTUyNyw4 ICs1MjcsOCBAQCBwcm90b2NvbCB0byBtYWtlIG5vZGVzIGFncmVlIG9uIGEgc2VyaWFsaXphYmxl IHRyYW5zYWN0aW9uYWwgb3JkZXIuCiAgIDwvcGFyYT4KIAogICA8cGFyYT4KLSAgIEl0IHNob3Vs ZCBiZSBub3RlZCB0aGF0IGxvZyBzaGlwcGluZyBpcyBhc3luY2hyb25vdXMsIGkuZS4sIHRoZSBX QUwKLSAgIHJlY29yZHMgYXJlIHNoaXBwZWQgYWZ0ZXIgdHJhbnNhY3Rpb24gY29tbWl0LiBBcyBh IHJlc3VsdCwgdGhlcmUgaXMgYQorICAgSXQgc2hvdWxkIGJlIG5vdGVkIHRoYXQgbG9nIHNoaXBw aW5nIGlzIGFzeW5jaHJvbm91cywgaS5lLiwgdGhlIHByaW1hcnkgc2VydmVyIGRvZXMKKyAgIG5v dCB3YWl0IHVudGlsIHRoZSBzdGFuZGJ5IHJlY2VpdmVzIHRoZSBkYXRhLiAgQXMgYSByZXN1bHQs IHRoZXJlIGlzIGEKICAgIHdpbmRvdyBmb3IgZGF0YSBsb3NzIHNob3VsZCB0aGUgcHJpbWFyeSBz ZXJ2ZXIgc3VmZmVyIGEgY2F0YXN0cm9waGljCiAgICBmYWlsdXJlOyB0cmFuc2FjdGlvbnMgbm90 IHlldCBzaGlwcGVkIHdpbGwgYmUgbG9zdC4gIFRoZSBzaXplIG9mIHRoZQogICAgZGF0YSBsb3Nz IHdpbmRvdyBpbiBmaWxlLWJhc2VkIGxvZyBzaGlwcGluZyBjYW4gYmUgbGltaXRlZCBieSB1c2Ug b2YgdGhlCi0tIAoyLjUxLjAKCg== --=-sjHGzuuTD4vUuBnnXbey--