rust/Materialize: Materialize 是一个实时数据集成平台，能够创建并持续更新整个组织内事务数据的一致视图。其 SQL 接口使实时数据的服务和访问变得民主化。Materialize 可以部署在您基础设施运行的任何地方。

title: "CREATE SOURCE: PostgreSQL" description: "Connecting Materialize to a PostgreSQL database for Change Data Capture (CDC)." pagerank: 40 menu: main:

parent: 'create-source'
identifier: cs_postgres
name: PostgreSQL
weight: 20

aliases:

/sql/create-source/postgresql ---

{{% create-source/intro %}} Materialize supports PostgreSQL (11+) as a data source. To connect to a PostgreSQL instance, you first need to create a connection that specifies access and authentication parameters. Once created, a connection is reusable across multiple CREATE SOURCE statements. {{% /create-source/intro %}}

{{< warning >}} Before creating a PostgreSQL source, you must set up logical replication in the upstream database. For step-by-step instructions, see the integration guide for your PostgreSQL service: AlloyDB, Amazon RDS, Amazon Aurora, Azure DB, Google Cloud SQL, Self-hosted. {{< /warning >}}

Syntax

`with_options`

Field	Use
_srcname	The name for the source.
IF NOT EXISTS	Do nothing (except issuing a notice) if a source with the same name already exists. Default.
IN CLUSTER _clustername	The cluster to maintain this source.
CONNECTION _connectionname	The name of the PostgreSQL connection to use in the source. For details on creating connections, check the `CREATE CONNECTION` documentation page.
FOR ALL TABLES	Create subsources for all tables in the publication.
FOR SCHEMAS ( _schemalist )	Create subsources for specific schemas in the publication.
FOR TABLES ( _tablelist )	Create subsources for specific tables in the publication.
EXPOSE PROGRESS AS _progress_subsourcename	The name of the progress collection for the source. If this is not specified, the progress collection will be named `<src_name>_progress`. For more information, see Monitoring source progress.
RETAIN HISTORY FOR _retentionperiod	*Private preview. This option has known performance or stability issues and is under active development.* Duration for which Materialize retains historical data, which is useful to implement durable subscriptions. Accepts positive interval values (e.g. `'1hr'`). Default: `1s`.

`CONNECTION` options

Field	Value	Description
`PUBLICATION`	`text`	Required. The PostgreSQL publication (the replication data set containing the tables to be streamed to Materialize).
`TEXT COLUMNS`	A list of names	Decode data as `text` for specific columns that contain PostgreSQL types that are unsupported in Materialize.

Features

Change data capture

This source uses PostgreSQL's native replication protocol to continually ingest changes resulting from INSERT, UPDATE and DELETE operations in the upstream database — a process also known as change data capture.

For this reason, you must configure the upstream PostgreSQL database to support logical replication before creating a source in Materialize. For step-by-step instructions, see the integration guide for your PostgreSQL service: AlloyDB, Amazon RDS, Amazon Aurora, Azure DB, Google Cloud SQL, Self-hosted.

Creating a source

To avoid creating multiple replication slots in the upstream PostgreSQL database and minimize the required bandwidth, Materialize ingests the raw replication stream data for some specific set of tables in your publication.

CREATE SOURCE mz_source
  FROM POSTGRES CONNECTION pg_connection (PUBLICATION 'mz_source')
  FOR ALL TABLES;

When you define a source, Materialize will automatically:

Create a replication slot in the upstream PostgreSQL database (see PostgreSQL replication slots).

The name of the replication slot created by Materialize is prefixed with materialize_ for easy identification, and can be looked up in mz_internal.mz_postgres_sources.
```
SELECT id, replication_slot FROM mz_internal.mz_postgres_sources;
```
```
   id   |             replication_slot
--------+----------------------------------------------
 u8     | materialize_7f8a72d0bf2a4b6e9ebc4e61ba769b71
```

Create a subsource for each original table in the publication.

SHOW SOURCES;

         name         |   type
----------------------+-----------
 mz_source            | postgres
 mz_source_progress   | progress
 table_1              | subsource
 table_2              | subsource

And perform an initial, snapshot-based sync of the tables in the publication before it starts ingesting change events.

Incrementally update any materialized or indexed views that depend on the source as change events stream in, as a result of INSERT, UPDATE and DELETE operations in the upstream PostgreSQL database.

It's important to note that the schema metadata is captured when the source is initially created, and is validated against the upstream schema upon restart. If you create new tables upstream after creating a PostgreSQL source and want to replicate them to Materialize, the source must be dropped and recreated.

PostgreSQL replication slots

Each source ingests the raw replication stream data for all tables in the specified publication using a single replication slot. This allows you to minimize the performance impact on the upstream database, as well as reuse the same source across multiple materializations.

{{< warning >}} Make sure to delete any replication slots if you stop using Materialize, or if either the Materialize or PostgreSQL instances crash. To look up the name of the replication slot created for each source, use mz_internal.mz_postgres_sources. {{< /warning >}}

If you delete all objects that depend on a source without also dropping the source, the upstream replication slot will linger and continue to accumulate data so that the source can resume in the future. To avoid unbounded disk space usage, make sure to use DROP SOURCE or manually delete the replication slot.

For PostgreSQL 13+, it is recommended that you set a reasonable value for max_slot_wal_keep_size to limit the amount of storage used by replication slots.

PostgreSQL schemas

CREATE SOURCE will attempt to create each upstream table in the same schema as the source. This may lead to naming collisions if, for example, you are replicating schema1.table_1 and schema2.table_1. Use the FOR TABLES clause to provide aliases for each upstream table, in such cases, or to specify an alternative destination schema in Materialize.

CREATE SOURCE mz_source
  FROM POSTGRES CONNECTION pg_connection (PUBLICATION 'mz_source')
  FOR TABLES (schema1.table_1 AS s1_table_1, schema2_table_1 AS s2_table_1);

Monitoring source progress

By default, PostgreSQL sources expose progress metadata as a subsource that you can use to monitor source ingestion progress. The name of the progress subsource can be specified when creating a source using the EXPOSE PROGRESS AS clause; otherwise, it will be named <src_name>_progress.

The following metadata is available for each source as a progress subsource:

Field	Type	Meaning
`lsn`	`uint8`	The last Log Sequence Number (LSN) consumed from the upstream PostgreSQL replication stream.

And can be queried using:

SELECT lsn
FROM <src_name>_progress;

The reported LSN should increase as Materialize consumes new WAL records from the upstream PostgreSQL database. For more details on monitoring source ingestion progress and debugging related issues, see Troubleshooting.

Known limitations

{{% include-md file="shared-content/postgres-considerations.md" %}}

Examples

{{< important >}} Before creating a PostgreSQL source, you must set up logical replication in the upstream database. For step-by-step instructions, see the integration guide for your PostgreSQL service: AlloyDB, Amazon RDS, Amazon Aurora, Azure DB, Google Cloud SQL, Self-hosted. {{< /important >}}

Creating a connection

A connection describes how to connect and authenticate to an external system you want Materialize to read data from.

Once created, a connection is reusable across multiple CREATE SOURCE statements. For more details on creating connections, check the CREATE CONNECTION documentation page.

CREATE SECRET pgpass AS '<POSTGRES_PASSWORD>';

CREATE CONNECTION pg_connection TO POSTGRES (
    HOST 'instance.foo000.us-west-1.rds.amazonaws.com',
    PORT 5432,
    USER 'postgres',
    PASSWORD SECRET pgpass,
    SSL MODE 'require',
    DATABASE 'postgres'
);

If your PostgreSQL server is not exposed to the public internet, you can tunnel the connection through an AWS PrivateLink service or an SSH bastion host.

CREATE CONNECTION privatelink_svc TO AWS PRIVATELINK (
    SERVICE NAME 'com.amazonaws.vpce.us-east-1.vpce-svc-0e123abc123198abc',
    AVAILABILITY ZONES ('use1-az1', 'use1-az4')
);

CREATE SECRET pgpass AS '<POSTGRES_PASSWORD>';

CREATE CONNECTION pg_connection TO POSTGRES (
    HOST 'instance.foo000.us-west-1.rds.amazonaws.com',
    PORT 5432,
    USER 'postgres',
    PASSWORD SECRET pgpass,
    AWS PRIVATELINK privatelink_svc,
    DATABASE 'postgres'
);

For step-by-step instructions on creating AWS PrivateLink connections and configuring an AWS PrivateLink service to accept connections from Materialize, check this guide.

CREATE CONNECTION ssh_connection TO SSH TUNNEL (
    HOST 'bastion-host',
    PORT 22,
    USER 'materialize',
);

CREATE CONNECTION pg_connection TO POSTGRES (
    HOST 'instance.foo000.us-west-1.rds.amazonaws.com',
    PORT 5432,
    SSH TUNNEL ssh_connection,
    DATABASE 'postgres'
);

For step-by-step instructions on creating SSH tunnel connections and configuring an SSH bastion server to accept connections from Materialize, check this guide.

Creating a source {#create-source-example}

Create subsources for all tables included in the PostgreSQL publication

CREATE SOURCE mz_source
    FROM POSTGRES CONNECTION pg_connection (PUBLICATION 'mz_source')
    FOR ALL TABLES;

Create subsources for all tables from specific schemas included in the PostgreSQL publication

CREATE SOURCE mz_source
  FROM POSTGRES CONNECTION pg_connection (PUBLICATION 'mz_source')
  FOR SCHEMAS (public, project);

Create subsources for specific tables included in the PostgreSQL publication

CREATE SOURCE mz_source
  FROM POSTGRES CONNECTION pg_connection (PUBLICATION 'mz_source')
  FOR TABLES (table_1, table_2 AS alias_table_2);

Handling unsupported types

If the publication contains tables that use data types unsupported by Materialize, use the TEXT COLUMNS option to decode data as text for the affected columns. This option expects the upstream names of the replicated table and column (i.e. as defined in your PostgreSQL database).

CREATE SOURCE mz_source
  FROM POSTGRES CONNECTION pg_connection (
    PUBLICATION 'mz_source',
    TEXT COLUMNS (upstream_table_name.column_of_unsupported_type)
  ) FOR ALL TABLES;

Handling errors and schema changes

{{< include-md file="shared-content/schema-changes-in-progress.md" >}}

To handle upstream schema changes or errored subsources, use the DROP SOURCE syntax to drop the affected subsource, and then ALTER SOURCE...ADD SUBSOURCE to add the subsource back to the source.

-- List all subsources in mz_source
SHOW SUBSOURCES ON mz_source;

-- Get rid of an outdated or errored subsource
DROP SOURCE table_1;

-- Start ingesting the table with the updated schema or fix
ALTER SOURCE mz_source ADD SUBSOURCE table_1;

Adding subsources

When adding subsources to a PostgreSQL source, Materialize opens a temporary replication slot to snapshot the new subsources' current states. After completing the snapshot, the table will be kept up-to-date, like all other tables in the publication.

Dropping subsources

Dropping a subsource prevents Materialize from ingesting any data from it, in addition to dropping any state that Materialize previously had for the table.

postgres.md 14 KB

Permalink History Raw

Syntax

`with_options`

`CONNECTION` options

Features

Change data capture

Creating a source

PostgreSQL replication slots

PostgreSQL schemas

Monitoring source progress

Known limitations

Examples

Creating a connection

Creating a source {#create-source-example}

Handling unsupported types

Handling errors and schema changes

Adding subsources

Dropping subsources

Related pages

postgres.md 14 KB Permalink History Raw

Syntax

with_options

CONNECTION options

Features

Change data capture

Creating a source

PostgreSQL replication slots

PostgreSQL schemas

Monitoring source progress

Known limitations

Examples

Creating a connection

Creating a source {#create-source-example}

Handling unsupported types

Handling errors and schema changes

Adding subsources

Dropping subsources

Related pages

postgres.md 14 KB

Permalink History Raw

`with_options`

`CONNECTION` options