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| author | Michael Paquier <michael@paquier.xyz> | 2021-10-23 14:43:03 +0900 |
|---|---|---|
| committer | Michael Paquier <michael@paquier.xyz> | 2021-10-23 14:43:03 +0900 |
| commit | 1e9475694b0ae2cf1204d01d2ef6ad86f3c7cac8 (patch) | |
| tree | 532e630ee97941377e703dd458ceb2709515ade5 | |
| parent | 92316a4582a5714d4e494aaf90360860e7fec37a (diff) | |
| download | postgresql-1e9475694b0ae2cf1204d01d2ef6ad86f3c7cac8.tar.gz postgresql-1e9475694b0ae2cf1204d01d2ef6ad86f3c7cac8.zip | |
doc: Describe calculation method of streaming start for pg_receivewal
The documentation was imprecise about the starting LSN used for WAL
streaming if nothing can be found in the local archive directory
defined with the pg_receivewal command, so be more talkative on this
matter.
Extracted from a larger patch by the same author.
Author: Ronan Dunklau, Michael Paquier
Discussion: https://postgr.es/m/18708360.4lzOvYHigE@aivenronan
Backpatch-through: 10
| -rw-r--r-- | doc/src/sgml/ref/pg_receivewal.sgml | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/doc/src/sgml/ref/pg_receivewal.sgml b/doc/src/sgml/ref/pg_receivewal.sgml index 45b544cf498..6da8b2be8c0 100644 --- a/doc/src/sgml/ref/pg_receivewal.sgml +++ b/doc/src/sgml/ref/pg_receivewal.sgml @@ -76,6 +76,29 @@ PostgreSQL documentation </para> <para> + The starting point of the write-ahead log streaming is calculated when + <application>pg_receivewal</application> starts: + <orderedlist> + <listitem> + <para> + First, scan the directory where the WAL segment files are written and + find the newest completed segment file, using as starting point the + beginning of the next WAL segment file. This is calculated independently + on the compression method used to compress each segment. + </para> + </listitem> + + <listitem> + <para> + If a starting point cannot be calculated with the previous method, + the latest WAL flush location is used as reported by the server from + a <literal>IDENTIFY_SYSTEM</literal> command. + </para> + </listitem> + </orderedlist> + </para> + + <para> If the connection is lost, or if it cannot be initially established, with a non-fatal error, <application>pg_receivewal</application> will retry the connection indefinitely, and reestablish streaming as soon |