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.
What is slonik?
slonik. is the word for a “little elephant,” and is the name of the program used to configure the cluster. In effect, the “little elephant” tells the cluster, “here’s what you need to do!”
What is Pgpool II?
Pgpool-II is a proxy software that sits between PostgreSQL servers and a PostgreSQL database client. It provides the following features: 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.
Why is the Postgres logo an elephant?
Indeed, the name comes from the Russian word “слоны” (slony) which means “elephants”. From this Postgres project, we get the following terminology: Slony – the plural word for elephants, which indicates that a cluster consists of multiple databases.
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 does Postgres logical replication work?
PostgreSQL logical replication uses WAL to record the logical changes independent from specific architecture or version. The subscriber first receives a copy of a replicated database from the publisher. These changes should be replicated in the subscriber database to ensure that the two databases remain in sync.
What is Pgpool and PgBouncer?
PgBouncer serves as a connection pooler for Postgres. Pgpool is an option for handling those functions in addition to connection pooling. Postgres Load Balancing, Replication, and more. Pgpool – now in its second major iteration, so Pgpool-II – is more of a Swiss Army knife of Postgres middleware functionality.
Why do we need Pgpool?
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, and other connection parameters if any) comes in. It reduces the connection overhead, and improves system’s overall throughput.
What is pooling in PostgreSQL?
Share. Connection pooling refers to the method of creating a pool of connections and caching those connections so that it can be reused again. PostgreSQL has a postmaster process, which spawns new processes for each new connection to the database.
How does PG bouncer work?
PgBouncer is an open-source, lightweight, single-binary connection pooler for PostgreSQL. It can pool connections to one or more databases (on possibly different servers) and serve clients over TCP and Unix domain sockets. PgBouncer maintains a pool of connections for each unique user, database pair.
How many subscribers does Slony-I replication system support?
Slony-I is a “master to multiple slaves” replication system supporting cascading (e.g. – a node can feed another node which feeds another node…) and failover. Single origin (master), up to 20 subscribers.
Are there any drawbacks to using Slony-I?
The main drawback to Slony-I even as a replication system is the complexity of its setup and administration. The design of the system, with the database itself being used for queueing row updates, also significantly increases the amount of data writing and I/O done by the DBMS.
What are the main concepts of schema therapy?
The four main concepts in the Schema Therapy model are: Early Maladaptive Schemas, Schema Domains, Coping Styles, and Schema Modes. The 18 Early Maladaptive Schemas are self-defeating, core themes or patterns that we keep repeating throughout our lives.
What is the Big Picture for the development of Slony-I?
The big picture for the development of Slony-I is that it is a master-slave replication system that includes all features and capabilities needed to replicate large databases to a reasonably limited number of slave systems.