# CREATE TABLE: PostgreSQL source table
Create a read-only table from a PostgreSQL source (new syntax).
In Materialize, you can create read-only tables from [PostgreSQL sources created
using the new syntax](/sql/create-source/postgres-v2/).

> **Note:** You must be on **v26+** to use the new syntax.


## Syntax

> **Note:** Source-populated tables are **read-only** tables. Users **cannot** perform write
> operations
> ([`INSERT`](/sql/insert/)/[`UPDATE`](/sql/update/)/[`DELETE`](/sql/delete/)) on
> these tables.


To create a read-only table from a [source](/sql/create-source/) connected
(via native connector) to an external PostgreSQL:


```mzsql
CREATE TABLE [IF NOT EXISTS] <table_name> FROM SOURCE <source_name> (REFERENCE <upstream_table>)
[WITH (
    TEXT COLUMNS (<column_name> [, ...])
  | EXCLUDE COLUMNS (<column_name> [, ...])
  | PARTITION BY (<column_name> [, ...])
  [, ...]
)]
;

```

| Syntax element | Description |
| --- | --- |
| **IF NOT EXISTS** | *Optional.* If specified, do not throw an error if the table with the same name already exists. Instead, issue a notice and skip the table creation.  {{< include-md file="content/headless/create-table-if-not-exists-tip.md" >}}  |
| `<table_name>` |  The name of the table to create. Names for tables must follow the [naming guidelines](/sql/identifiers/#naming-restrictions).  |
| `<source_name>` |  The name of the [source](/sql/create-source/) associated with the reference object from which to create the table.  |
| **(REFERENCE <upstream_table>)** |  The name of the upstream table from which to create the table. You can create multiple tables from the same upstream table.  To find the upstream tables available in your [source](/sql/create-source/), you can use the following query, substituting your source name for `<source_name>`:  <br>  ```mzsql SELECT refs.* FROM mz_internal.mz_source_references refs, mz_sources s WHERE s.name = '<source_name>' -- substitute with your source name AND refs.source_id = s.id; ```  |
| **WITH (<with_option>[,...])** | The following `<with_option>`s are supported:  \| Option \| Description \| \|--------\|-------------\| \| `TEXT COLUMNS (<column_name> [, ...])` \|*Optional.* If specified, decode data as `text` for the listed column(s),such as for unsupported data types. See also [supported types](#supported-data-types). \| \| `EXCLUDE COLUMNS (<column_name> [, ...])`\| *Optional.* If specified,exclude the listed column(s) from the table, such as for unsupported data types. See also [supported types](#supported-data-types).\| \| `PARTITION BY (<column_name> [, ...])` \| {{< include-md file="content/headless/partition-by-option-description.md" >}} \|  |


## Details

### DDL transaction block

For performance, when issuing multiple `CREATE TABLE FROM SOURCE...` statements,
use within a [transaction block](/sql/begin/#ddl-only-transactions).

### Source-populated tables and snapshotting

Creating the tables from sources starts the [snapshotting](/ingest-data/#snapshotting) process. Snapshotting syncs the
currently available data into Materialize. Because the initial snapshot is
persisted in the storage layer atomically (i.e., at the same ingestion
timestamp), you are not able to query the table until snapshotting is complete.

> **Note:** During the snapshotting, the data ingestion for the existing tables for the same
> source is temporarily blocked. As such, if possible, you can resize the cluster
> to speed up the snapshotting process and once the process finishes, resize the
> cluster for steady-state. You can monitor the snapshot progress on the overview
> page for the source in the Materialize console.

### Supported data types

<p>Materialize natively supports the following PostgreSQL types (including the
array type for each of the types):</p>
<ul style="column-count: 3"><li><code>bool</code></li><li><code>bpchar</code></li><li><code>bytea</code></li><li><code>char</code></li><li><code>date</code></li><li><code>daterange</code></li><li><code>float4</code></li><li><code>float8</code></li><li><code>int2</code></li><li><code>int2vector</code></li><li><code>int4</code></li><li><code>int4range</code></li><li><code>int8</code></li><li><code>int8range</code></li><li><code>interval</code></li><li><code>json</code></li><li><code>jsonb</code></li><li><code>numeric</code></li><li><code>numrange</code></li><li><code>oid</code></li><li><code>text</code></li><li><code>time</code></li><li><code>timestamp</code></li><li><code>timestamptz</code></li><li><code>tsrange</code></li><li><code>tstzrange</code></li><li><code>uuid</code></li><li><code>varchar</code></li></ul>

Replicating tables that contain **unsupported [data types](/sql/types/)** is
possible via the `TEXT COLUMNS` option. The specified columns will be
treated as `text`; i.e., will not have the expected PostgreSQL type
features. For example:

* [`enum`]: When decoded as `text`, the implicit ordering of the original
  PostgreSQL `enum` type is not preserved; instead, Materialize will sort values
  as `text`.

* [`money`]: When decoded as `text`, resulting `text` value cannot be cast
back to `numeric`, since PostgreSQL adds typical currency formatting to the
output.

[`enum`]: https://www.postgresql.org/docs/current/datatype-enum.html
[`money`]: https://www.postgresql.org/docs/current/datatype-money.html


### Handling table schema changes

The use of `CREATE SOURCE` (new syntax) with `CREATE TABLE FROM SOURCE` allows
for the handling of the upstream DDL changes, specifically adding or dropping
columns in the upstream tables, without downtime. For details, see [PostgreSQL:
Handling upstream schema changes with zero
downtime](/ingest-data/postgres/source-versioning/).

#### Incompatible schema changes

All other schema changes to upstream tables will set the corresponding
Materialize tables into an error state, preventing reads from these tables.

To handle [incompatible schema changes](#incompatible-schema-changes), drop
the affected table [`DROP TABLE`](/sql/drop-table/) , and then, [`CREATE
TABLE FROM SOURCE`](/sql/create-table/) to recreate the table with the
updated schema.


### Upstream table truncation restrictions

Avoid truncating upstream tables that are being replicated into Materialize.
If a replicated upstream table is truncated, the corresponding
subsource(s)/table(s) in Materialize becomes inaccessible and will not
produce any data until it is recreated.

Instead of truncating, use an unqualified `DELETE` to remove all rows from
the upstream table:

```mzsql
DELETE FROM t;
```


### Inherited tables

When using [PostgreSQL table inheritance](https://www.postgresql.org/docs/current/tutorial-inheritance.html),
PostgreSQL serves data from `SELECT`s as if the inheriting tables' data is
also present in the inherited table. However, both PostgreSQL's logical
replication and `COPY` only present data written to the tables themselves,
i.e. the inheriting data is _not_ treated as part of the inherited table.

PostgreSQL sources use logical replication and `COPY` to ingest table data,
so inheriting tables' data will only be ingested as part of the inheriting
table, i.e. in Materialize, the data will not be returned when serving
`SELECT`s from the inherited table.


You can mimic PostgreSQL's `SELECT` behavior with inherited tables by
creating a materialized view that unions data from the inherited and
inheriting tables (using `UNION ALL`). However, if new tables inherit from
the table, data from the inheriting tables will not be available in the
view. You will need to add the inheriting tables via `CREATE TABLE .. FROM
SOURCE` and create a new view (materialized or non-) that unions the new
table.


## Privileges

The privileges required to execute this statement are:

- `CREATE` privileges on the containing schema.
- `USAGE` privileges on all types used in the table definition.
- `USAGE` privileges on the schemas that all types in the statement are
  contained in.

## Examples

### Create a table

> **Note:** You must be on **v26+** to use the new syntax.
> The example assumes you have configured your upstream PostgreSQL 11+ (i.e.,
> enabled logical replication, created the publication for the various tables and
> replication user, and updated the network configuration).
> For details about configuring your upstream system, see the [PostgreSQL
> integration guides](/ingest-data/postgres/#supported-versions-and-services).



To create new **read-only** tables from a source table, use the `CREATE
TABLE ... FROM SOURCE ... (REFERENCE <upstream_table>)` statement in a [DDL
transaction block](/sql/begin/#ddl-only-transactions). The following example
creates **read-only** tables `items` and `orders` from the PostgreSQL
source's `public.items` and `public.orders` tables (the schema is `public`).

{{< note >}}

- Although the example creates the tables with the same names as the
upstream tables, the tables in Materialize can have names that differ from
the referenced table names.

- For supported PostgreSQL data types, refer to [supported
types](/sql/create-table/postgres/#supported-data-types).

{{< /note >}}
```mzsql
/* This example assumes:
  - In the upstream PostgreSQL, you have defined:
    - replication user and password with the appropriate access.
    - a publication named `mz_source` for the `items` and `orders` tables.
  - In Materialize:
    - You have created a secret for the PostgreSQL password.
    - You have defined the connection to the upstream PostgreSQL.
    - You have used the connection to create a source.

   For example (substitute with your configuration):
      CREATE SECRET pgpass AS '<replication user password>'; -- substitute
      CREATE CONNECTION pg_connection TO POSTGRES (
        HOST '<hostname>',          -- substitute
        DATABASE <db>,              -- substitute
        USER <replication user>,    -- substitute
        PASSWORD SECRET pgpass
        -- [, <network security configuration> ]
      );

      CREATE SOURCE pg_source
      FROM POSTGRES CONNECTION pg_connection (
        PUBLICATION 'mz_source'       -- substitute
      );
*/

BEGIN;
CREATE TABLE items
FROM SOURCE pg_source(REFERENCE public.items)
;
CREATE TABLE orders
FROM SOURCE pg_source(REFERENCE public.orders)
;
COMMIT;

```
{{< include-md
file="content/headless/create-table-from-source-snapshotting.md" >}}

{{< include-md file="content/headless/create-table-if-not-exists-tip.md" >}}


Once the snapshotting process completes and the table is in the running state, you can query the table:
```mzsql
SELECT * FROM items;

```

## Related pages

- [`CREATE SOURCE: PostgreSQL (New Syntax)`](/sql/create-source/postgres-v2/)
- [`DROP TABLE`](/sql/drop-table)