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Developer guide

for Fedora 40

Install PostgreSql

dnf install postgresql-server

for Fedora 40, this will install PostgreSQL 15

Install pgmoneta_ext

Pre-install

Basic dependencies

dnf install git gcc cmake make postgresql-server-devel

Generate user and developer guide

This process is optional. If you choose not to generate the PDF and HTML files, you can opt out of downloading these dependencies, and the process will automatically skip the generation.

  1. Download dependencies

    dnf install pandoc texlive-scheme-basic

  2. Download Eisvogel

    Use the command pandoc --version to locate the user data directory. On Fedora systems, this directory is typically located at /root/.local/share/pandoc.

    Download the Eisvogel template for pandoc, please visit the pandoc-latex-template repository. For a standard installation, you can follow the steps outlined below.

    wget https://github.com/Wandmalfarbe/pandoc-latex-template/releases/download/2.4.2/Eisvogel-2.4.2.tar.gz
tar -xzf Eisvogel-2.4.2.tar.gz
mkdir /root/.local/share/pandoc # user data directory
mkdir /root/.local/share/pandoc/templates
mv eisvogel.latex /root/.local/share/pandoc/templates/

  3. Add package for latex

    Download the additional packages required for generating PDF and HTML files.

    dnf install 'tex(footnote.sty)' 'tex(footnotebackref.sty)' 'tex(pagecolor.sty)' 'tex(hardwrap.sty)' 'tex(mdframed.sty)' 'tex(sourcesanspro.sty)' 'tex(ly1enc.def)' 'tex(sourcecodepro.sty)' 'tex(titling.sty)' 'tex(csquotes.sty)' 'tex(zref-abspage.sty)' 'tex(needspace.sty)'

Initialize PostgreSQL

Open a new window, switch to the postgres user.

sudo su -
su - postgres

For Fedora, if you use dnf to install your postgresql, chances are the binary file is in /usr/bin/

export PATH=/usr/bin:$PATH
initdb /tmp/pgsql

Since we initialized the database in /tmp, the data in this directory might be removed after you go offline, depending on your OS configuration. If you want to make it permanent, choose a different directory.

Build

git clone https://github.com/pgmoneta/pgmoneta_ext
cd pgmoneta_ext
mkdir build
cd build
cmake ..
make
sudo make install

Configuration

Our project, pgmoneta_ext, is primarily designed for pgmoneta to perform delta backups. To ensure pgmoneta_ext functions properly, we should use repl to test all extension functions and verify they work correctly with pgmoneta.

If you have already set up the repl role, you can skip this section.

1. Remove default access

Remove last lines from /tmp/pgsql/pg_hba.conf. The path mentioned can be found using the SQL command SHOW hba_file;.

host    all             all             127.0.0.1/32            trust
host    all             all             ::1/128                 trust
host    replication     all             127.0.0.1/32            trust
host    replication     all             ::1/128                 trust

2. Add access for users and a database

Add new lines to /tmp/pgsql/pg_hba.conf

host    postgres         repl            127.0.0.1/32            scram-sha-256
host    postgres         repl            ::1/128                 scram-sha-256
host    replication      repl            127.0.0.1/32            scram-sha-256
host    replication      repl            ::1/128                 scram-sha-256

3. Set password_encryption

Set password_encryption value in /tmp/pgsql/postgresql.conf to be scram-sha-256

password_encryption = scram-sha-256

For version 13, the default is md5, while for version 14 and above, it is scram-sha-256. Therefore, you should ensure that the value in /tmp/pgsql/postgresql.conf matches the value in /tmp/pgsql/pg_hba.conf.

4. Set replication level

Set wal_level value in /tmp/pgsql/postgresql.conf to be replica

wal_level = replica

5. Start PostgreSQL

pg_ctl  -D /tmp/pgsql/ start

Here, you may encounter issues such as the port being occupied or permission being denied. If you experience a failure, you can go to /tmp/pgsql/log to check the reason.

You can use

pg_isready

to test

6. Add role repl

psql postgres
CREATE ROLE repl WITH LOGIN REPLICATION PASSWORD 'secretpassword';
\q

7. Add replication slot

Add the required replication slot

psql postgres
SELECT pg_create_physical_replication_slot('repl', true, false);
\q

Here, the command in the context of pgmoneta is used to create a replication slot to manage and retain WAL segments necessary for replication and backup operations, ensuring data consistency and reliability.

For more details, please check the pgmoneta.

8. Verify access

For the role repl (pgmoneta) use secretpassword

psql -h localhost -p 5432 -U repl postgres
\q

9. Grant superuser privileges

Since some functions require the role to have superuser privileges, you can grant these privileges to the repl role using the following SQL command. Please proceed with caution: granting superuser privileges bypasses all permission checks, allowing unrestricted access to the database, which can pose security risks. We are committed to enhancing privilege security in future updates.

ALTER ROLE repl WITH SUPERUSER;

The following SQL command can revoke the superuser privileges:

ALTER USER repl WITH NOSUPERUSER;

Check

If you just want to verify if pgmoneta_ext was installed successfully, you can use the postgres role to test.

  1. Log into PostgreSQL

    psql

  2. Create a new test database

    CREATE DATABASE testdb;

  3. Enter the database

    \c testdb

  4. Follow the SQL commands below to check the function

    DROP EXTENSION IF EXISTS pgmoneta_ext;
CREATE EXTENSION pgmoneta_ext;
SELECT pgmoneta_ext_version();

You should see

 pgmoneta_ext_version 
----------------------
 0.1.0
(1 row)

If you encounter any errors, you can check the log to find the reason. The log's location can be found in the postgresql.conf file.

# These are only used if logging_collector is on:
log_directory = 'log'                   # directory where log files are written,
                                        # can be absolute or relative to PGDATA
log_filename = 'postgresql-%a.log'      # log file name pattern,
                                        # can include strftime() escapes