Need help finding all possible parameters for wal_level

On Fri, Sep 1, 2017 at 3:36 PM, None <espressobeanies@gmail.com> wrote:

Hi,

I'm searching for all of the possible parameters for setting the
"wal_level" outlined in the PostgreSQL Streaming Replication article:

https://wiki.postgresql.org/wiki/Streaming_Replication

I currently see hot_standby, but I can't find a list for all of the
parameters that setting will take. Where can I find that?

Thanks!

They are here:
https://www.postgresql.org/docs/current/static/runtime-config-wal.html

Note that there have been some changes (additions of replica and logical)
for this setting in the latest versions.

Well, so that's what doesn't make sense. Other documentation also indicates
a 'hot_standby' setting and I'm looking to see if it can do 'warm_standby'
as well. I was hoping for a complete list because it seems scattered right
now.

On Fri, Sep 1, 2017 at 10:43 AM, Pantelis Theodosiou <ypercube@gmail.com>
wrote:

On Fri, Sep 1, 2017 at 3:46 PM, None <espressobeanies@gmail.com> wrote:

Well, so that's what doesn't make sense. Other documentation also
indicates a 'hot_standby' setting and I'm looking to see if it can do
'warm_standby' as well. I was hoping for a complete list because it seems
scattered right now.

All the options are there.

In releases prior to 9.6, this parameter also allowed the values *archive*

and *hot_standby*. These are still accepted but mapped to *replica*.

The link is for the current version (9.6). Visit the links for previous
versions, if you intend to use one.

None <espressobeanies@gmail.com> writes:

Hi,

I'm searching for all of the possible parameters for setting the
"wal_level" outlined in the PostgreSQL Streaming Replication article:

https://wiki.postgresql.org/wiki/Streaming_Replication

I currently see hot_standby, but I can't find a list for all of the
parameters that setting will take. Where can I find that?

You didn't even tell us what version is relevant here but let's assume 9.6...

https://www.postgresql.org/docs/9.6/static/runtime-config-wal.html

wal_level (enum)

wal_level determines how much information is written to the WAL. The default value is minimal, which writes only the information needed to recover from a crash or immediate shutdown.
replica adds logging required for WAL archiving as well as information required to run read-only queries on a standby server. Finally, logical adds information necessary to support
logical decoding. Each level includes the information logged at all lower levels. This parameter can only be set at server start.

In minimal level, WAL-logging of some bulk operations can be safely skipped, which can make those operations much faster (see Section 14.4.7). Operations in which this optimization can
be applied include:

CREATE TABLE AS
CREATE INDEX
CLUSTER
COPY into tables that were created or truncated in the same transaction

But minimal WAL does not contain enough information to reconstruct the data from a base backup and the WAL logs, so replica or higher must be used to enable WAL archiving (archive_mode)
and streaming replication.

In logical level, the same information is logged as with replica, plus information needed to allow extracting logical change sets from the WAL. Using a level of logical will increase the
WAL volume, particularly if many tables are configured for REPLICA IDENTITY FULL and many UPDATE and DELETE statements are executed.

In releases prior to 9.6, this parameter also allowed the values archive and hot_standby. These are still accepted but mapped to replica.

Thanks!

--
Jerry Sievers
Postgres DBA/Development Consulting
e: postgres.consulting@comcast.net
p: 312.241.7800

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On Fri, Sep 1, 2017 at 7:46 AM, None <espressobeanies@gmail.com> wrote:

Well, so that's what doesn't make sense. Other documentation also
indicates a 'hot_standby' setting and I'm looking to see if it can do
'warm_standby' as well. I was hoping for a complete list because it seems
scattered right now.

​The documentation is version specific. All of the values allowed for the
specified version are listed on that page. There is not and never was a
"warm_standby" value. The valid values for wal_level do not fully restrict
how one can setup their standby configuration but rather define the minimum
possible configuration (which is basically either cold or warn standby
depending on whether you decide to run an independent standby server full
time). The settings at
https://www.postgresql.org/docs/current/static/runtime-config-replication.html
are use if you wish to convert the warm standby into a hot standby. In
either case the relevant wal_level needs to be "replica". It was deemed
unnecessary to distinguish between "archive (cold/warn) and hot_standby" in
9.6 - in terms of what information was recorded in the WAL.

David J.

Hi all,

Thank you. I'm using 9.6. I found all the available options in the
'postgresql.conf' file on the server itself. The explanations are good, but
I was looking for something like this:

# minimal, archive, hot_standby, or logical

I saw the 'replica' option in the documentation, but not in the conf file
itself, so I dunno if it's supported.

On Fri, Sep 1, 2017 at 10:58 AM, David G. Johnston <
david.g.johnston@gmail.com> wrote:

None wrote:

Hi all,

Thank you. I'm using 9.6. I found all the available options in the
'postgresql.conf' file on the server itself. The explanations are good, but
I was looking for something like this:

# minimal, archive, hot_standby, or logical

I saw the 'replica' option in the documentation, but not in the conf file
itself, so I dunno if it's supported.

Hmm. Commit b555ed810267 (in 9.6) removed values 'archive' and
'hot_standby' and introduced 'replica' to substitute them, and updated
postgresql.conf.sample to account for that. If you're using a
postgresql.conf file that has the outdated comment, I'm guessing that
the conf file was copied from an older installation somehow (which is
very common since the file largely remains compatible).

--
�lvaro Herrera https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

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Good call,

Thank you

On Fri, Sep 1, 2017 at 11:55 AM, Alvaro Herrera <alvherre@alvh.no-ip.org>
wrote: