ClickHouse/docs/en/engines/table-engines/integrations/materialized-postgresql.md

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12	MateriaziePostgreSQL

MaterializedPostgreSQL

Creating a Table

CREATE TABLE test.postgresql_replica (key UInt64, value UInt64)
ENGINE = MaterializedPostgreSQL('postgres1:5432', 'postgres_database', 'postgresql_replica', 'postgres_user', 'postgres_password')
PRIMARY KEY key;

Requirements

• Setting wal_levelto logical and max_replication_slots to at least 2 in the postgresql config file.

• A table with engine MaterializedPostgreSQL must have a primary key - the same as a replica identity index (default: primary key) of a postgres table (See details on replica identity index).

• Only database Atomic is allowed.

Virtual columns

• _version (UInt64)

• _sign (Int8)

These columns do not need to be added, when table is created. They are always accessible in SELECT query. _version column equals LSN position in WAL, so it might be used to check how up-to-date replication is.

CREATE TABLE test.postgresql_replica (key UInt64, value UInt64)
ENGINE = MaterializedPostgreSQL('postgres1:5432', 'postgres_database', 'postgresql_replica', 'postgres_user', 'postgres_password')
PRIMARY KEY key;

SELECT key, value, _version FROM test.postgresql_replica;

Warning

1. TOAST values convertion is not supported. Default value for the data type will be used.