> ## Documentation Index
> Fetch the complete documentation index at: https://docs.risingwave.com/llms.txt
> Use this file to discover all available pages before exploring further.
# Information schema
> The information schema consists of a set of views that contain information about the objects defined in the current database.
## Tables
The `information_schema.tables` view contains all tables, views, sinks, and materialized views defined in the current database.
Materialized views are specific to the information schema of RisingWave. They are not included in the information schema of PostgreSQL.
The `information_schema.tables` view contains the following columns.
| Column | Type | Description |
| :------------------- | :------ | :---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| table\_catalog | varchar | Name of the current database. |
| table\_schema | varchar | Name of the schema that contains the table, view, or materialized view. The default schema for user-created objects is public. |
| table\_name | varchar | Name of the table, view, or materialized view. |
| table\_type | varchar | Type of the table, view, or materialized view. BASE TABLE for a user-defined table, VIEW for a non-materialized view, MATERIALIZED VIEW for a materialized view, and SYSTEM TABLE for a system table. |
| is\_insertable\_into | varchar | YES if the table or view is insertable into, NO if not. User-defined tables are always insertable, while views and materialized views are not necessarily. |
## Table constraints
The `table_constraints` view contains all constraints for tables that the current user owns or has privileges other than `SELECT` on.
The `table_constraints` view contains the following columns.
| Column | Type | Description |
| -------------------- | ------- | ----------------------------------------------------------------------------------- |
| `constraint_catalog` | varchar | Name of the database that contains the constraint. |
| `constraint_schema` | varchar | Name of the schema that contains the constraint. |
| `constraint_name` | varchar | Name of the constraint. |
| `table_catalog` | varchar | Name of the database that contains the table. |
| `table_schema` | varchar | Name of the schema that contains the table. |
| `table_name` | varchar | Name of the table. |
| `constraint_type` | varchar | Type of the constraint: `PRIMARY KEY`(p), `UNIQUE`(u), `CHECK`(c), or `EXCLUDE`(x). |
| `is_deferrable` | varchar | `YES` if the constraint is deferrable, `NO` if not. |
| `initially_deferred` | varchar | `YES` if the constraint is deferrable and initially deferred, `NO` if not. |
| `enforced` | varchar | `YES` if the constraint is validated and enforced, `NO` if not. |
**TEMPORARY LIMITATION**
This view assumes the constraint schema is the same as the table schema, since `pg_catalog.pg_constraint` only supports primary key.
## Schemata
The `schemata` view contains all accessible schemas in the current database for users, either by way of being the owner or having some privilege.
It contains the following columns.
| Column | Type | Description |
| ------------------------------- | ------- | ---------------------------------------------------------------------- |
| `catalog_name` | varchar | Name of the database containing the schema. |
| `schema_name` | varchar | Name of the schema. |
| `schema_owner` | varchar | Name of the schema owner. |
| `default_character_set_catalog` | varchar | Name of the database that contains the schema's default character set. |
| `default_character_set_schema` | varchar | Name of the schema containing the default character set. |
| `default_character_set_name` | varchar | Name of the schema's default character set. |
| `sql_path` | varchar | SQL path specification for the schema. |
## Views
The `information_schema.views` view contains information about the views in the database.
It contains the following columns.
| Column | Type | Description |
| :---------------- | :------ | :----------------------------------------- |
| `table_catalog` | varchar | Name of the current database. |
| `table_schema` | varchar | Name of the schema that contains the view. |
| `table_name` | varchar | Name of the view. |
| `view_definition` | varchar | SQL statement that defines the view. |
**TEMPORARY LIMITATION**
Users with access to `information_schema.views` can potentially access all views, which poses a security risk. We are working to resolve this limitation. Once the fix is implemented, this message will be removed.
## Columns
The `information_schema.columns` view contains information about columns of all tables, views, and materialized views in the database.
| Column | Type | Description |
| :---------------------- | :---------- | :----------------------------------------------------------------------------------------------------------------------------------- |
| `table_catalog` | varchar | Name of the current database. |
| `table_schema` | varchar | Name of the schema that contains the table, sink, view, or materialized view. The default schema for user-created objects is public. |
| `table_name` | varchar | Name of the table, sink, view, or materialized view. |
| `column_name` | varchar | Name of the column. |
| `ordinal_position` | int32 | Ordinal position of the column within the table (count starts at 1). |
| `is_nullable` | varchar | YES if the column is possibly nullable; NO if it is known not nullable. |
| `data_type` | varchar | Data type of the column. |
| `is_generated` | varchar | ALWAYS if the column has a generated value; NEVER if it doesn't. |
| `generation_expression` | varchar | Expression for generating values when `is_generated` is ALWAYS. |
| `_rw_timestamp` | timestamptz | Internal timestamp indicating when each row was last updated. Only available in the batch query. |
## How to use the information schema views?
You can use various information schema views to determine the makeup of tables, sinks, views, and materialized views in a database.
For example, you can query for names and types of all the tables, views, and materialized views in the current database:
```sql theme={null}
SELECT table_name, table_type
FROM information_schema.tables;
```
To query for all of the columns in a table, sink, view, or materialized view called `taxi_trip`:
```sql theme={null}
SELECT column_name
FROM information_schema.columns
WHERE table_name='taxi_trip';
```
To find out tables, sinks, views, and materialized views that contain a column called `trip_id`:
```sql theme={null}
SELECT table_name
FROM information_schema.columns
WHERE column_name='trip_id';
```