What is slony replication?
What is Slony? Slony-I (referred to as just ‘Slony’ from here on out) is a third-party replication system for PostgreSQL that dates back to before version 8.0, making it one of the older options for replication available. It operates as a trigger-based replication method that is a ‘master to multiple slaves’ solution.
How does PostgreSQL replication work?
Streaming replication in PostgreSQL works on log shipping. Every transaction in postgres is written to a transaction log called WAL (write-ahead log) to achieve durability. A slave uses these WAL segments to continuously replicate changes from its master.
How do you do logical replication in PostgreSQL?
To perform logical replication in PostgreSQL, you’ve to change the wal_level = logical parameter. The parameter tells the server to store additional information in WAL for converting binary changes into logical ones. To change the value of this parameter, you have to open the postgresql. conf file.
Does PostgreSQL support replication?
Streaming replication, a standard feature of PostgreSQL, allows the updated information on the primary server to be transferred to the standby server in real time, so that the databases of the primary server and standby server can be kept in sync.
What is Pgpool?
Pgpool-II is a proxy software that sits between PostgreSQL servers and a PostgreSQL database client. It provides the following features: Connection Pooling.
What is Pglogical?
pglogical is a logical replication system implemented entirely as a PostgreSQL extension. Fully integrated, it requires no triggers or external programs. This alternative to physical replication is a highly efficient method of replicating data using a publish/subscribe model for selective replication.
How many types of replication are there in PostgreSQL?
There are three types of replication: Streaming Replication: PostgreSQL made this type of replication available in version 9 and later. Replicas are available for run-only select queries. The primary requirement for this type is the source and replica databases must be the same major version.
What is the difference between physical and logical replication?
Logical replication is a method of replicating data objects and their changes based upon their replication identity (usually a primary key). We use the term logical in contrast to physical replication, which uses exact block addresses and byte-by-byte replication.
What is replication slot in Postgres?
A replication slot is a feature in PostgreSQL that ensures that the master server will retain the WAL logs that are needed by the replicas even when they are disconnected from the master.
What is Pgpool and PgBouncer?
PgBouncer allows limiting connections per-pool, per-database, per-user or per-client. Winner! Pgpool-II allows limiting the overall number of connections only. Connection queue. PgBouncer supports queuing at the application level (i.e. PgBouncer maintains the queue).
What is Pgpool used for?
What is pgpool-II? pgpool-II maintains established connections to the PostgreSQL servers, and reuses them whenever a new connection with the same properties (i.e. user name, database, protocol version) comes in. It reduces the connection overhead, and improves system’s overall throughput.
How do you use Pglogical?
To use pglogical the provider and subscriber must be running PostgreSQL 9.4 or newer. The pglogical extension must be installed on both provider and subscriber. You must CREATE EXTENSION pglogical on both. Tables on the provider and subscriber must have the same names and be in the same schema.
What is Pglogical PostgreSQL?
What is the difference between logical and physical replication?
What is physical replication in PostgreSQL?
Physical replication methods are used to maintain a full copy of the entire data of a single cluster (in Postgres, a cluster is a set of databases managed by a single main Postgres server process called a postmaster), typically on another machine.
What is asynchronous replication in PostgreSQL?
PostgreSQL streaming replication is asynchronous by default. If the primary server crashes then some transactions that were committed may not have been replicated to the standby server, causing data loss. The amount of data loss is proportional to the replication delay at the time of failover.
What is Wal_level in Postgres?
wal_level determines how much information is written to the WAL. The default value is replica , which writes enough data to support WAL archiving and replication, including running read-only queries on a standby server.
What is Max_wal_senders?
max_wal_senders ( integer ) Specifies the maximum number of concurrent connections from standby servers or streaming base backup clients (i.e., the maximum number of simultaneously running WAL sender processes). The default is 10 . The value 0 means replication is disabled.
Is Pgbouncer a load balancer?
Now there’s pgbouncer-rr-patch(pgbouncer fork by AWS) that can do load balancing: Routing: intelligently send queries to different database servers from one client connection; use it to partition or load balance across multiple servers/clusters.
How do you use Pgpool?
First, we must learn how to install, configure pgpool-II and database nodes before using replication or parallel query.
- 1.1. Installing pgpool-II. Installing pgpool-II is very easy.
- 1.2. Configuration Files.
- 1.3. Configuring PCP Commands.
- 1.4. Preparing Database Nodes.
- 1.5. Starting/Stopping pgpool-II.