How to Achieve PostgreSQL High Availability with pgBouncer | Severalnines (2023)

FAQs

How do I get high availability in PostgreSQL? ›

In general, a single PgBouncer can process up to 10,000 connections. 1,000 or so can be active at one time. The exact numbers will depend on your configuration and the amount of data you it is copying between the database and the application.

The primary benefit of PgBouncer is to improve idle connections and short-lived connections at the database server. PgBouncer uses a more lightweight model that utilizes asynchronous I/O, and only uses actual Postgres connections when needed, that is, when inside an open transaction, or when a query is active.

Pgpool-II does support passwordless authentication through PAM or SSL-certificates. However, these must be set up outside the PostgreSQL system, while PgBouncer can offload this to the PostgreSQL server. PgBouncer provides a virtual database that reports various useful statistics.

To set up servers in a high-availability configuration, you install the server on separate systems and connect the servers to the same database. Then, you configure a load balancer to distribute the traffic between the servers. Instead of accessing the servers directly, users access the load balancer URL.

PostgreSQL's default connection limit is set to 100 concurrent connections, which is also the default on Compose for PostgreSQL. Many connection pooling libraries and tools also set connections to 100 by default.

PgBouncer has three pooling modes available: transaction pooling, session pooling, and statement pooling. It's important that you understand how each work. The pooling mode used: Determines how long a server connection stays assigned to a client connection.

The PgBouncer process will reload its configuration files and update changeable settings. This includes the main configuration file as well as the files specified by the settings auth_file and auth_hba_file . PgBouncer notices when a configuration file reload changes the connection parameters of a database definition.

If you're simply filtering the data and data fits in memory, Postgres is capable of parsing roughly 5-10 million rows per second (assuming some reasonable row size of say 100 bytes).

How many max connections can Postgres handle? ›

The default is typically 100 connections, but might be less if your kernel settings will not support it (as determined during initdb).

PostgreSQL Connection Limits

At provision, Databases for PostgreSQL sets the maximum number of connections to your PostgreSQL database to 115. 15 connections are reserved for the superuser to maintain the state and integrity of your database, and 100 connections are available for you and your applications.

pgcat is a connection pool like pgbouncer, and shares part of the logical way it's working, but it has a fundamental difference: it allows to use multiple databases for a single client connection. pgbouncer only ever connects a client to a single database.

pgAgent is a tool used for scheduling jobs for PostgreSQL databases. It also has more powerful scheduling capabilities than the often-used cron because it is specifically built for handling Postgres tasks. For example, pgAgent can schedule multiple steps without a batch script or without repeating the command.

Pgpool-II is a proxy software that sits between PostgreSQL servers and a PostgreSQL database client. It provides the following features: Connection Pooling.

One of these specialized procedures that is supported by Postgres is called WAL archiving. The Postgres WAL (Write-Ahead Log) is the location in the Postgres cluster where all changes to the cluster's data files are recorded before they're written to the heap.

DataSource objects that implement connection pooling also produce a connection to the particular data source that the DataSource class represents. The connection object that the getConnection method returns is a handle to a PooledConnection object rather than being a physical connection.

Write-Ahead Logging ( WAL ) is a standard method for ensuring data integrity. A detailed description can be found in most (if not all) books about transaction processing.

Either the Network Time Protocol (NTP) must be configured or the clock must be set identical on both devices to allow timestamps and call timers to match. Virtual router forwarding (VRF) must be defined in the same order on both active and standby routers for an accurate synchronization of data.

How to configure high availability Palo Alto? ›

Using the “alter system set” command to raise the maximum number of connections: The alter system command is used to alter directly in the PostgreSQL software's system files. In this command, we will increase the previous set of maximum system connections.

By default, SQL Server allows a maximum of 32767 concurrent connections which is the maximum number of users that can simultaneously log in to the SQL server instance.

Read-committed is the default isolation level. Read-committed — The default PostgreSQL transaction isolation level. It prevents sessions from seeing data from concurrent transactions until it is committed.

pool_size — Just like it sounds: the size of the pool. The default is 20. For Heroku server-side plans, the default is half of your plan's connection limit.

Average pooling method smooths out the image and hence the sharp features may not be identified when this pooling method is used. Max pooling selects the brighter pixels from the image. It is useful when the background of the image is dark and we are interested in only the lighter pixels of the image.

Pool size. It's not a that simple, PgBouncer has 5 different setting related to limiting connection count! You can specify pool_size for each proxied database. If not set, it defaults to default_pool_size setting, which again by default has a value of 20 .

The pg_stat_statements module provides a means for tracking planning and execution statistics of all SQL statements executed by a server. The module must be loaded by adding pg_stat_statements to shared_preload_libraries in postgresql. conf , because it requires additional shared memory.

Connection pooling means that connections are reused rather than created each time a connection is requested. To facilitate connection reuse, a memory cache of database connections, called a connection pool, is maintained by a connection pooling module as a layer on top of any standard JDBC driver product.

What is database connection pooling? Database connection pooling is a way to reduce the cost of opening and closing connections by maintaining a “pool” of open connections that can be passed from database operation to database operation as needed.

How to handle 1 million requests per second? ›

As commercial database vendors are bragging about their capabilities we decided to push PostgreSQL to the next level and exceed 1 billion rows per second to show what we can do with Open Source. To those who need even more: 1 billion rows is by far not the limit - a lot more is possible. Watch and see how we did it.

The system is based entirely on MySQL and processes an average of 3,000 queries per second and handles 10,000 queries per second at peak times! This amounts to over 300 million queries per day.

Table Count Limit. Technically Postgres does not have a limit on the number of tables. However, each table is a file on the OS filesystem.

PostgreSQL is an enterprise-class Open Source Database Management System. It is scalable, flexible, and extensible making it the DB of choice to build next-generation, large scale applications.

PostgreSQL uses only one core.

Fortunately, PostgreSQL has the ability to combine multiple indexes (including multiple uses of the same index) to handle cases that cannot be implemented by single index scans. The system can form AND and OR conditions across several index scans.

So a query is limited to 1 gigabyte (2^30) in size, minus 1 byte for a terminating null byte.

Multiple Instances

Adding a new PostgreSQL is as simple as executing pg_createcluster with the version of the PostgreSQL and clustername. The files belonging to this database system will be owned by user "postgres". This user must also own the server process. The database cluster will be initialized with locale "en_US.

PgBouncer is a light-weight connection pool manager for Greenplum and PostgreSQL. PgBouncer maintains a pool for connections for each database and user combination. PgBouncer either creates a new database connection for a client or reuses an existing connection for the same user and database.

What is Postgres High Availability? ›

PostgreSQL High Availability contains the measure of a system's resilience in the face of infrastructure failure. PostgreSQL maintains the high availability of its clusters by ensuring that a secondary server will take over if the primary server crashes.

When PostgreSQL receives a connection request it will check the pg_hba. conf file to verify that the machine from which the application is requesting a connection has rights to connect to the specified database.

It reduces the connection overhead, and improves system's overall throughput. Load Balancing. If a database is replicated (because running in either replication mode or native replication mode), performing a SELECT query on any server will return the same result.

Etcd is a fault-tolerant, distributed key-value store used to store the state of the Postgres cluster. Using Patroni, all of the Postgres nodes make use of etcd to keep the Postgres cluster up and running.

pg_stat_activity is a system view that allows you to identify active SQL queries in AnalyticDB for PostgreSQL instances. The pg_stat_activity view shows a server process and its related session and query in each row.

Open source databases like Postgres, MariaDB, MySQL, and Redis are great options for HA but generally don't include a built-in HA solution.

The Always On availability groups feature is a high-availability and disaster-recovery solution that provides an enterprise-level alternative to database mirroring. Introduced in SQL Server 2012 (11. x), Always On availability groups maximizes the availability of a set of user databases for an enterprise.

To configure a high-availability cluster, you store shared files on network storage. Then, you configure multiple servers, set each server to access the same files and database, and configure a load balancer to distribute the traffic between the servers.

SQL Server Transactional Replication is a real time, database level, high availability solution, that consists of one primary server, known as Publisher, that distributes all the database tables, or selected tables known as articles, to one or more secondary servers, known as Subscribers, that can be also used for ...

How do you check if high availability is enabled in SQL Server? ›

To configure your Db2® database solution for high availability, you must: schedule database maintenance activities; configure the primary and standby database servers to know about each other and their respective roles in the event of a failure; and configure any cluster managing software to transfer workload from a ...

Use SQL Server Management Studio

Expand the Always On High Availability node and the Availability Groups node. Right-click the availability group, and select one of the following commands: To launch the Add Database to Availability Group Wizard, select the Add Database command.

Application Server provides the High Availability Database (HADB) for high availability storage of HTTP session and stateful session bean data. HADB is designed to support up to 99.999% service and data availability with load balancing, failover, and state recovery.

In Object Explorer, right-click a server and select Properties. Click the Connections node. Under Remote server connections, in the Remote query timeout box, type or select a value from 0 through 2,147,483,647 to set the maximum number seconds for SQL Server to wait before timing out.

What is the difference between failover and high availability? ›

Failover is a means of achieving high availability (HA). Think of HA as a feature and failover as one possible implementation of that feature. Failover is not always the only consideration when achieving HA.