Thread: how to distinguish between using the server as a standby or for executing a targeted recovery in PG 11?
how to distinguish between using the server as a standby or for executing a targeted recovery in PG 11?
From
Bharath Rupireddy
Date:
Hi, I'm trying to set up a postgres server with version 11 in targeted recovery mode (for the first time after my journey started with postgres) and I came across the explanation at [1] in PG 12 and newer versions that we have a clear differentiation as to what is the "standby" mode or "targeted recovery" mode. How do we differentiate these two modes in PG 11? Can anyone please help me with it? PS: hackers-list may not be the right place to ask, but I'm used to seeking help from it. [1] From the https://www.postgresql.org/docs/12/runtime-config-wal.html: "19.5.4. Archive Recovery This section describes the settings that apply only for the duration of the recovery. They must be reset for any subsequent recovery you wish to perform. “Recovery” covers using the server as a standby or for executing a targeted recovery. Typically, standby mode would be used to provide high availability and/or read scalability, whereas a targeted recovery is used to recover from data loss. To start the server in standby mode, create a file called standby.signal in the data directory. The server will enter recovery and will not stop recovery when the end of archived WAL is reached, but will keep trying to continue recovery by connecting to the sending server as specified by the primary_conninfo setting and/or by fetching new WAL segments using restore_command. For this mode, the parameters from this section and Section 19.6.3 are of interest. Parameters from Section 19.5.5 will also be applied but are typically not useful in this mode. To start the server in targeted recovery mode, create a file called recovery.signal in the data directory. If both standby.signal and recovery.signal files are created, standby mode takes precedence. Targeted recovery mode ends when the archived WAL is fully replayed, or when recovery_target is reached. In this mode, the parameters from both this section and Section 19.5.5 will be used." Regards, Bharath Rupireddy.
Re: how to distinguish between using the server as a standby or for executing a targeted recovery in PG 11?
From
"Euler Taveira"
Date:
On Fri, Sep 24, 2021, at 1:46 PM, Bharath Rupireddy wrote:
I'm trying to set up a postgres server with version 11 in targetedrecovery mode (for the first time after my journey started withpostgres) and I came across the explanation at [1] in PG 12 and newerversions that we have a clear differentiation as to what is the"standby" mode or "targeted recovery" mode. How do we differentiatethese two modes in PG 11? Can anyone please help me with it?
It seems you have to rely on parsing recovery.conf. However, someone can modify
it after starting Postgres. In this case, you have to use a debugger such as
gdb /path/to/postgres -p $(pgrep -f 'postgres: startup recovering') -quiet -batch -ex 'p StandbyMode' -ex 'quit'
Unfortunately, there is no simple way such as checking if a .signal file exists.
Re: how to distinguish between using the server as a standby or for executing a targeted recovery in PG 11?
From
Andrew Dunstan
Date:
On 9/24/21 12:46 PM, Bharath Rupireddy wrote: > Hi, > > I'm trying to set up a postgres server with version 11 in targeted > recovery mode (for the first time after my journey started with > postgres) and I came across the explanation at [1] in PG 12 and newer > versions that we have a clear differentiation as to what is the > "standby" mode or "targeted recovery" mode. How do we differentiate > these two modes in PG 11? Can anyone please help me with it? > > PS: hackers-list may not be the right place to ask, but I'm used to > seeking help from it. > see <https://www.postgresql.org/docs/11/recovery-target-settings.html> and <https://www.postgresql.org/docs/11/standby-settings.html> (And yes, pgsql-general would be the right forum) cheers andrew -- Andrew Dunstan EDB: https://www.enterprisedb.com
Re: how to distinguish between using the server as a standby or for executing a targeted recovery in PG 11?
From
Bharath Rupireddy
Date:
On Tue, Sep 28, 2021 at 7:39 PM Andrew Dunstan <andrew@dunslane.net> wrote: > > > On 9/24/21 12:46 PM, Bharath Rupireddy wrote: > > Hi, > > > > I'm trying to set up a postgres server with version 11 in targeted > > recovery mode (for the first time after my journey started with > > postgres) and I came across the explanation at [1] in PG 12 and newer > > versions that we have a clear differentiation as to what is the > > "standby" mode or "targeted recovery" mode. How do we differentiate > > these two modes in PG 11? Can anyone please help me with it? > > > > PS: hackers-list may not be the right place to ask, but I'm used to > > seeking help from it. > > > > > see <https://www.postgresql.org/docs/11/recovery-target-settings.html> > and <https://www.postgresql.org/docs/11/standby-settings.html> Thanks! It looks like the 'standby_mode = off' in the recovery.conf with a 'recovery_target' makes the server to be in "targeted recovery" mode. Regards, Bharath Rupireddy.