Previously, we had consecutive, very short chapters called "Generic
WAL" and "Custom WAL Resource Managers," explaining different approaches
to the same problem. Merge them into a single chapter. Explain most
of the differences between the approaches in the chapter's
introductory text, rather than in the individual sections.
Discussion: http://postgr.es/m/46ac50c1-6b2a-404f-a683-b67af6ab56e9@eisentraut.org
Allow extensions to specify a new custom resource manager (rmgr),
which allows specialized WAL. This is meant to be used by a Table
Access Method or Index Access Method.
Prior to this commit, only Generic WAL was available, which offers
support for recovery and physical replication but not logical
replication.
Reviewed-by: Julien Rouhaud, Bharath Rupireddy, Andres Freund
Discussion: https://postgr.es/m/ed1fb2e22d15d3563ae0eb610f7b61bb15999c0a.camel%40j-davis.com
For DocBook XML compatibility, don't use SGML empty tags (</>) anymore,
replace by the full tag name. Add a warning option to catch future
occurrences.
Alexander Lakhin, Jürgen Purtz
Rename this function to GenericXLogRegisterBuffer() to make it clearer
what it does, and leave room for other sorts of "register" actions in
future. Also, replace its "bool isNew" argument with an integer flags
argument, so as to allow adding more flags in future without an API
break.
Alexander Korotkov, adjusted slightly by me
This routine is unsafe as implemented, because it invalidates the page
image pointers returned by previous GenericXLogRegister() calls.
Rather than complicate the API or the implementation to avoid that,
let's just get rid of it; the use-case for having it seems much
too thin to justify a lot of work here.
While at it, do some wordsmithing on the SGML docs for generic WAL.
This interface is designed to give an access to WAL for extensions which
could implement new access method, for example. Previously it was
impossible because restoring from custom WAL would need to access system
catalog to find a redo custom function. This patch suggests generic way
to describe changes on page with standart layout.
Bump XLOG_PAGE_MAGIC because of new record type.
Author: Alexander Korotkov with a help of Petr Jelinek, Markus Nullmeier and
minor editorization by my
Reviewers: Petr Jelinek, Alvaro Herrera, Teodor Sigaev, Jim Nasby,
Michael Paquier
Robert Haas
Jeff Davis
Peter Eisentraut
Tom Lane
Teodor Sigaev