> ## Documentation Index
> Fetch the complete documentation index at: https://private-7c7dfe99-mintlify-8c05c8a2.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.
> Creates a ClickHouse table with an initial data dump of a PostgreSQL table and starts the replication process.
# MaterializedPostgreSQL table engine
export const CloudNotSupportedBadge = () => {
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};
ClickHouse Cloud users are recommended to use [ClickPipes](/integrations/clickpipes/home) for PostgreSQL replication to ClickHouse. This natively supports high-performance Change Data Capture (CDC) for PostgreSQL.
Creates ClickHouse table with an initial data dump of PostgreSQL table and starts the replication process, i.e. it executes a background job to apply new changes as they happen on PostgreSQL table in the remote PostgreSQL database.
This table engine is experimental. To use it, set `allow_experimental_materialized_postgresql_table` to 1 in your configuration files or by using the `SET` command:
```sql theme={null}
SET allow_experimental_materialized_postgresql_table=1
```
If more than one table is required, it is highly recommended to use the [MaterializedPostgreSQL](/reference/engines/database-engines/materialized-postgresql) database engine instead of the table engine and use the `materialized_postgresql_tables_list` setting, which specifies the tables to be replicated (will also be possible to add database `schema`). It will be much better in terms of CPU, fewer connections and fewer replication slots inside the remote PostgreSQL database.
1. The [wal\_level](https://www.postgresql.org/docs/current/runtime-config-wal.html) setting must have a value `logical` and `max_replication_slots` parameter must have a value at least `2` in the PostgreSQL config file.
2. A table with `MaterializedPostgreSQL` engine must have a primary key — the same as a replica identity index (by default: primary key) of a PostgreSQL table (see [details on replica identity index](/reference/engines/database-engines/materialized-postgresql#requirements)).
3. Only database [Atomic](https://en.wikipedia.org/wiki/Atomicity_\(database_systems\)) is allowed.
4. The `MaterializedPostgreSQL` table engine only works for PostgreSQL versions >= 11 as the implementation requires the [pg\_replication\_slot\_advance](https://pgpedia.info/p/pg_replication_slot_advance.html) PostgreSQL function.
Virtual columns
* `_version` — Transaction counter. Type: [UInt64](/reference/data-types/int-uint).
* `_sign` — Deletion mark. Type: [Int8](/reference/data-types/int-uint). Possible values:
* `1` — Row is not deleted,
* `-1` — Row is deleted.
These columns do not need to be added when a 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.
```sql theme={null}
CREATE TABLE postgresql_db.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 postgresql_db.postgresql_replica;
```
Replication of [**TOAST**](https://www.postgresql.org/docs/9.5/storage-toast.html) values is not supported. The default value for the data type will be used.