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describe

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Description

Using describe command to query metadata of the index. describe command could be only used as the first command in the PPL query.

Syntax

describe <dataSource>.<schema>.<tablename>

  • dataSource: optional. If dataSource is not provided, it resolves to opensearch dataSource.
  • schema: optional. If schema is not provided, it resolves to default schema.
  • tablename: mandatory. describe command must specify which tablename to query from.

Example 1: Fetch all the metadata

The example describes accounts index.

PPL query:

os> describe accounts;
fetched rows / total rows = 11/11
+----------------+-------------+------------+----------------+-----------+-----------+-------------+---------------+----------------+----------------+----------+---------+------------+---------------+------------------+-------------------+------------------+-------------+---------------+--------------+-------------+------------------+------------------+--------------------+
| TABLE_CAT      | TABLE_SCHEM | TABLE_NAME | COLUMN_NAME    | DATA_TYPE | TYPE_NAME | COLUMN_SIZE | BUFFER_LENGTH | DECIMAL_DIGITS | NUM_PREC_RADIX | NULLABLE | REMARKS | COLUMN_DEF | SQL_DATA_TYPE | SQL_DATETIME_SUB | CHAR_OCTET_LENGTH | ORDINAL_POSITION | IS_NULLABLE | SCOPE_CATALOG | SCOPE_SCHEMA | SCOPE_TABLE | SOURCE_DATA_TYPE | IS_AUTOINCREMENT | IS_GENERATEDCOLUMN |
|----------------+-------------+------------+----------------+-----------+-----------+-------------+---------------+----------------+----------------+----------+---------+------------+---------------+------------------+-------------------+------------------+-------------+---------------+--------------+-------------+------------------+------------------+--------------------|
| docTestCluster | null        | accounts   | account_number | null      | long      | null        | null          | null           | 10             | 2        | null    | null       | null          | null             | null              | 0                |             | null          | null         | null        | null             | NO               |                    |
| docTestCluster | null        | accounts   | firstname      | null      | text      | null        | null          | null           | 10             | 2        | null    | null       | null          | null             | null              | 1                |             | null          | null         | null        | null             | NO               |                    |
| docTestCluster | null        | accounts   | address        | null      | text      | null        | null          | null           | 10             | 2        | null    | null       | null          | null             | null              | 2                |             | null          | null         | null        | null             | NO               |                    |
| docTestCluster | null        | accounts   | balance        | null      | long      | null        | null          | null           | 10             | 2        | null    | null       | null          | null             | null              | 3                |             | null          | null         | null        | null             | NO               |                    |
| docTestCluster | null        | accounts   | gender         | null      | text      | null        | null          | null           | 10             | 2        | null    | null       | null          | null             | null              | 4                |             | null          | null         | null        | null             | NO               |                    |
| docTestCluster | null        | accounts   | city           | null      | text      | null        | null          | null           | 10             | 2        | null    | null       | null          | null             | null              | 5                |             | null          | null         | null        | null             | NO               |                    |
| docTestCluster | null        | accounts   | employer       | null      | text      | null        | null          | null           | 10             | 2        | null    | null       | null          | null             | null              | 6                |             | null          | null         | null        | null             | NO               |                    |
| docTestCluster | null        | accounts   | state          | null      | text      | null        | null          | null           | 10             | 2        | null    | null       | null          | null             | null              | 7                |             | null          | null         | null        | null             | NO               |                    |
| docTestCluster | null        | accounts   | age            | null      | long      | null        | null          | null           | 10             | 2        | null    | null       | null          | null             | null              | 8                |             | null          | null         | null        | null             | NO               |                    |
| docTestCluster | null        | accounts   | email          | null      | text      | null        | null          | null           | 10             | 2        | null    | null       | null          | null             | null              | 9                |             | null          | null         | null        | null             | NO               |                    |
| docTestCluster | null        | accounts   | lastname       | null      | text      | null        | null          | null           | 10             | 2        | null    | null       | null          | null             | null              | 10               |             | null          | null         | null        | null             | NO               |                    |
+----------------+-------------+------------+----------------+-----------+-----------+-------------+---------------+----------------+----------------+----------+---------+------------+---------------+------------------+-------------------+------------------+-------------+---------------+--------------+-------------+------------------+------------------+--------------------+

Example 2: Fetch metadata with condition and filter

The example retrieves columns with type long in accounts index.

PPL query:

os> describe accounts | where TYPE_NAME="long" | fields COLUMN_NAME;
fetched rows / total rows = 3/3
+----------------+
| COLUMN_NAME    |
|----------------|
| account_number |
| balance        |
| age            |
+----------------+

Example 3: Fetch metadata for table in prometheus dataSource

The example retrieves table info for prometheus_http_requests_total metric in prometheus dataSource.

PPL query:

os> describe my_prometheus.prometheus_http_requests_total;
fetched rows / total rows = 6/6
+---------------+--------------+--------------------------------+-------------+-----------+
| TABLE_CATALOG | TABLE_SCHEMA | TABLE_NAME                     | COLUMN_NAME | DATA_TYPE |
|---------------+--------------+--------------------------------+-------------+-----------|
| my_prometheus | default      | prometheus_http_requests_total | handler     | keyword   |
| my_prometheus | default      | prometheus_http_requests_total | code        | keyword   |
| my_prometheus | default      | prometheus_http_requests_total | instance    | keyword   |
| my_prometheus | default      | prometheus_http_requests_total | @timestamp  | timestamp |
| my_prometheus | default      | prometheus_http_requests_total | @value      | double    |
| my_prometheus | default      | prometheus_http_requests_total | job         | keyword   |
+---------------+--------------+--------------------------------+-------------+-----------+