Since 11, it is possible to use a non-superuser role when using an
online source cluster with pg_rewind as long as the role has proper
permissions to execute on the source all the functions used by
pg_rewind, and the documentation stated that a superuser is necessary.
Let's add at the same time all the details needed to create such a
role.
A second confusion which comes a lot from users is that it is necessary
to issue a checkpoint on a freshly-promoted standby so as its control
file has up-to-date timeline information which is used by pg_rewind to
validate the operation. Let's document that properly. This is
back-patched down to 9.5 where pg_rewind has been introduced.
Author: Michael Paquier
Reviewed-by: Magnus Hagander
Discussion: https://postgr.es/m/CABUevEz5bpvbwVsYCaSMV80CBZ5-82nkMzbb+Bu=h1m=rLdn=g@mail.gmail.com
Backpatch-through: 9.5
This unifies the various ad hoc logging (message printing, error
printing) systems used throughout the command-line programs.
Features:
- Program name is automatically prefixed.
- Message string does not end with newline. This removes a common
source of inconsistencies and omissions.
- Additionally, a final newline is automatically stripped, simplifying
use of PQerrorMessage() etc., another common source of mistakes.
- I converted error message strings to use %m where possible.
- As a result of the above several points, more translatable message
strings can be shared between different components and between
frontends and backend, without gratuitous punctuation or whitespace
differences.
- There is support for setting a "log level". This is not meant to be
user-facing, but can be used internally to implement debug or
verbose modes.
- Lazy argument evaluation, so no significant overhead if logging at
some level is disabled.
- Some color in the messages, similar to gcc and clang. Set
PG_COLOR=auto to try it out. Some colors are predefined, but can be
customized by setting PG_COLORS.
- Common files (common/, fe_utils/, etc.) can handle logging much more
simply by just using one API without worrying too much about the
context of the calling program, requiring callbacks, or having to
pass "progname" around everywhere.
- Some programs called setvbuf() to make sure that stderr is
unbuffered, even on Windows. But not all programs did that. This
is now done centrally.
Soft goals:
- Reduces vertical space use and visual complexity of error reporting
in the source code.
- Encourages more deliberate classification of messages. For example,
in some cases it wasn't clear without analyzing the surrounding code
whether a message was meant as an error or just an info.
- Concepts and terms are vaguely aligned with popular logging
frameworks such as log4j and Python logging.
This is all just about printing stuff out. Nothing affects program
flow (e.g., fatal exits). The uses are just too varied to do that.
Some existing code had wrappers that do some kind of print-and-exit,
and I adapted those.
I tried to keep the output mostly the same, but there is a lot of
historical baggage to unwind and special cases to consider, and I
might not always have succeeded. One significant change is that
pg_rewind used to write all error messages to stdout. That is now
changed to stderr.
Reviewed-by: Donald Dong <xdong@csumb.edu>
Reviewed-by: Arthur Zakirov <a.zakirov@postgrespro.ru>
Discussion: https://www.postgresql.org/message-id/flat/6a609b43-4f57-7348-6480-bd022f924310@2ndquadrant.com
recovery.conf settings are now set in postgresql.conf (or other GUC
sources). Currently, all the affected settings are PGC_POSTMASTER;
this could be refined in the future case by case.
Recovery is now initiated by a file recovery.signal. Standby mode is
initiated by a file standby.signal. The standby_mode setting is
gone. If a recovery.conf file is found, an error is issued.
The trigger_file setting has been renamed to promote_trigger_file as
part of the move.
The documentation chapter "Recovery Configuration" has been integrated
into "Server Configuration".
pg_basebackup -R now appends settings to postgresql.auto.conf and
creates a standby.signal file.
Author: Fujii Masao <masao.fujii@gmail.com>
Author: Simon Riggs <simon@2ndquadrant.com>
Author: Abhijit Menon-Sen <ams@2ndquadrant.com>
Author: Sergei Kornilov <sk@zsrv.org>
Discussion: https://www.postgresql.org/message-id/flat/607741529606767@web3g.yandex.ru/
This is an option consistent with what pg_dump and pg_basebackup provide
which is useful for leveraging the I/O effort when testing things, not
to be used in a production environment.
Author: Michael Paquier
Reviewed-by: Heikki Linnakangas
Discussion: https://postgr.es/m/20180325122607.GB3707@paquier.xyz
When performing pg_rewind, the presence of a read-only file which is not
accessible for writes will cause a failure while processing. This can
cause the control file of the target data folder to be truncated,
causing it to not be reusable with a successive run.
Also, when pg_rewind fails mid-flight, there is likely no way to be able
to recover the target data folder anyway, in which case a new base
backup is the best option. A note is added in the documentation as
well about.
Reported-by: Christian H.
Author: Michael Paquier
Reviewed-by: Andrew Dunstan
Discussion: https://postgr.es/m/20180104200633.17004.16377%40wrigleys.postgresql.org
The target cluster that was rewound needs to perform recovery from
the checkpoint created at failover, which leads it to remove or recreate
some files and directories that may have been copied from the source
cluster. So pg_rewind can skip synchronizing such files and directories,
and which reduces the amount of data transferred during a rewind
without changing the usefulness of the operation.
Author: Michael Paquier
Reviewed-by: Anastasia Lubennikova, Stephen Frost and me
Discussion: https://postgr.es/m/20180205071022.GA17337@paquier.xyz
Since some preparation work had already been done, the only source
changes left were changing empty-element tags like <xref linkend="foo">
to <xref linkend="foo"/>, and changing the DOCTYPE.
The source files are still named *.sgml, but they are actually XML files
now. Renaming could be considered later.
In the build system, the intermediate step to convert from SGML to XML
is removed. Everything is build straight from the source files again.
The OpenSP (or the old SP) package is no longer needed.
The documentation toolchain instructions are updated and are much
simpler now.
Peter Eisentraut, Alexander Lakhin, Jürgen Purtz
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
"xlog" is not a particularly clear abbreviation for "write-ahead log",
and it sometimes confuses users into believe that the contents of the
"pg_xlog" directory are not critical data, leading to unpleasant
consequences. So, rename the directory to "pg_wal".
This patch modifies pg_upgrade and pg_basebackup to understand both
the old and new directory layouts; the former is necessary given the
purpose of the tool, while the latter merely avoids an unnecessary
backward-compatibility break.
We may wish to consider renaming other programs, switches, and
functions which still use the old "xlog" naming to also refer to
"wal". However, that's still under discussion, so let's do just this
much for now.
Discussion: CAB7nPqTeC-8+zux8_-4ZD46V7YPwooeFxgndfsq5Rg8ibLVm1A@mail.gmail.com
Michael Paquier
Allow pg_rewind to work when target timeline was switched. Now
user can return promoted standby to old master.
Target timeline history becomes a global variable. Index
in target timeline history is used in function interfaces instead of
specifying TLI directly. Thus, SimpleXLogPageRead() can easily start
reading XLOGs from next timeline when current timeline ends.
Author: Alexander Korotkov
Review: Michael Paquier
Earlier versions of this tool were available (and still are) on github.
Thanks to Michael Paquier, Alvaro Herrera, Peter Eisentraut, Amit Kapila,
and Satoshi Nagayasu for review.
Peter Eisentraut
Michael Paquier
Peter Eisentraut
Fujii Masao
Robert Haas
Bruce Momjian
Tom Lane
Teodor Sigaev
Heikki Linnakangas