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Consider this an EXPERIMENTAL feature mostly because it has not been tested yet on a wide variety of long running Druid clusters.

This extension allows users to configure, update, retrieve, and manage metadata stored in Druid's catalog. At present, only metadata about tables is stored in the catalog. This extension only supports MSQ based ingestion.

Configuration

To use this extension please make sure to include druid-catalog in the extensions load list.

Catalog Metadata

Tables

A user may define a table with a defined set of column names, and respective data types, along with other properties. When ingesting data into a table defined in the catalog, the DML query is validated against the definition of the table as defined in the catalog. This allows the user to omit the table's properties that are found in its definition, allowing queries to be more concise, and simpler to write. This also allows the user to ensure that the type of data being written into a defined column of the table is consistent with that columns definition, minimizing errors where unexpected data is written into a particular column of the table.

API Objects

TableSpec

A tableSpec defines a table

Property	Type	Description	Required	Default
`type`	String	the type of table. The only value supported at this time is `datasource`	yes	null
`properties`	Map<String, Object>	the table's defined properties. see table properties	no	null
`columns`	List<ColumnSpec>	the table's defined columns	no	null

Table Properties

PropertyKeyName	PropertyValueType	Description	Required	Default
`segmentGranularity`	String	determines how time-based partitioning is done. See Partitioning by time. Can specify any of the values as permitted for PARTITIONED BY. This property value may be overridden at query time, by specifying the PARTITIONED BY clause.	no	null
`sealed`	boolean	require all columns in the table schema to be fully declared before data is ingested. Setting this to true will cause failure when DML queries attempt to add undefined columns to the table.	no	false

ColumnSpec

Property	Type	Description	Required	Default
`name`	String	The name of the column	yes	null
`dataType`	String	The type of the column. Can be any column data type that is available to Druid. Depends on what extensions are loaded.	no	null
`properties`	Map<String, Object>	the column's defined properties. Non properties defined at this time.	no	null

APIs

Create or update a table

Update or create a new table containing the given table specification.

URL

POST /druid/coordinator/v1/catalog/schemas/{schema}/tables/{name}

Request body

The request object for this request is a TableSpec

Query parameters

The endpoint supports a set of optional query parameters to enforce optimistic locking, and to specify that a request is meant to update a table rather than create a new one. In the default case, with no query parameters set, this request will return an error if a table of the same name already exists in the schema specified.

Parameter	Type	Description
`version`	Long	the expected version of an existing table. The version must match. If not (or if the table does not exist), returns an error.
`overwrite`	boolean	if true, then overwrites any existing table. Otherwise, the operation fails if the table already exists.

Responses

Successfully submitted table spec. Returns an object that includes the version of the table created or updated:

{
    "version": 12345687
}

Error thrown due to bad request. Returns a JSON object detailing the error with the following format:

{
    "error": "A well-defined error code.",
    "errorMessage": "A message with additional details about the error."
}

Error thrown due to unexpected conditions. Returns a JSON object detailing the error with the following format:

{
    "error": "A well-defined error code.",
    "errorMessage": "A message with additional details about the error."
}

Sample request

The following example shows how to create a sealed table with several defined columns, and a defined segment granularity of "P1D"

curl "http://ROUTER_IP:ROUTER_PORT/druid/coordinator/v1/catalog/schemas/druid/tables/test_table" \
-X 'POST' \
--header 'Content-Type: application/json' \
--data '{
  "type": "datasource",
  "columns": [
    {
      "name": "__time",
      "dataType": "long"
    },
    {
      "name": "double_col",
      "dataType": "double"
    },
    {
      "name": "float_col",
      "dataType": "float"
    },
    {
      "name": "long_col",
      "dataType": "long"
    },
    {
      "name": "string_col",
      "dataType": "string"
    }
  ],
  "properties": {
    "segmentGranularity": "P1D",
    "sealed": true
  }
}'

Sample response

{
  "version": 1730965026295
}

Retrieve a table

URL

GET `/druid/coordinator/v1/catalog/schemas/{schema}/tables/{name}

Responses

Successfully retrieved corresponding table's TableSpec

Error thrown due to bad request. Returns a JSON object detailing the error with the following format:

{
    "error": "A well-defined error code.",
    "errorMessage": "A message with additional details about the error."
}

Error thrown due to unexpected conditions. Returns a JSON object detailing the error with the following format:

{
    "error": "A well-defined error code.",
    "errorMessage": "A message with additional details about the error."
}

Sample request

The following example shows how to retrieve a table named 'test_table' in schema 'druid'

curl "http://ROUTER_IP:ROUTER_PORT/druid/coordinator/v1/catalog/schemas/druid/tables/test_table"

Sample response

View the response

{
  "id": {
    "schema": "druid",
    "name": "test_table"
  },
  "creationTime": 1730965026295,
  "updateTime": 1730965026295,
  "state": "ACTIVE",
  "spec": {
    "type": "datasource",
    "properties": {
      "segmentGranularity": "P1D",
      "sealed": true
    },
    "columns": [
      {
        "name": "__time",
        "dataType": "long"
      },
      {
        "name": "double_col",
        "dataType": "double"
      },
      {
        "name": "float_col",
        "dataType": "float"
      },
      {
        "name": "long_col",
        "dataType": "long"
      },
      {
        "name": "string_col",
        "dataType": "string"
      }
    ]
  }
}

Delete a table

URL

DELETE `/druid/coordinator/v1/catalog/schemas/{schema}/tables/{name}

Responses

No response body

Error thrown due to bad request. Returns a JSON object detailing the error with the following format:

{
    "error": "A well-defined error code.",
    "errorMessage": "A message with additional details about the error."
}

Error thrown due to unexpected conditions. Returns a JSON object detailing the error with the following format:

{
    "error": "A well-defined error code.",
    "errorMessage": "A message with additional details about the error."
}

Sample request

The following example shows how to delete the a table named test_table in schema druid

curl -X 'DELETE' "http://ROUTER_IP:ROUTER_PORT/druid/coordinator/v1/catalog/schemas/druid/tables/test_table"

Sample response

No response body

Retrieve list of schema names

retrieve list of schema names

URL

GET `/druid/coordinator/v1/catalog/schemas

Responses

Successfully retrieved list of schema names

Error thrown due to bad request. Returns a JSON object detailing the error with the following format:

{
    "error": "A well-defined error code.",
    "errorMessage": "A message with additional details about the error."
}

Error thrown due to unexpected conditions. Returns a JSON object detailing the error with the following format:

{
    "error": "A well-defined error code.",
    "errorMessage": "A message with additional details about the error."
}

Sample request

The following example shows how to retrieve the list of schema names.

curl "http://ROUTER_IP:ROUTER_PORT/druid/coordinator/v1/catalog/schemas"

Sample response

[
  "INFORMATION_SCHEMA",
  "druid",
  "ext",
  "lookups",
  "sys",
  "view"
]

Retrieve list of table names in schema

Retrieve a list of table names in the schema.

URL

GET `/druid/coordinator/v1/catalog/schemas/{schema}/table

Responses

Successfully retrieved list of table names belonging to schema

Error thrown due to bad request. Returns a JSON object detailing the error with the following format:

{
    "error": "A well-defined error code.",
    "errorMessage": "A message with additional details about the error."
}

Error thrown due to unexpected conditions. Returns a JSON object detailing the error with the following format:

{
    "error": "A well-defined error code.",
    "errorMessage": "A message with additional details about the error."
}

Sample request

The following example shows how to retrieve all of the table names of tables belonging to the druid schema.

curl "http://ROUTER_IP:ROUTER_PORT/druid/coordinator/v1/catalog/schemas/druid/tables"

Sample response

[
  "test_table"
]

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Configuration

Catalog Metadata

Tables

API Objects

TableSpec

Table Properties

ColumnSpec

APIs

Create or update a table

URL

Request body

Query parameters

Responses

Sample request

Sample response

Retrieve a table

URL

Responses

Sample request

Sample response

Delete a table

URL

Responses

Sample request

Sample response

Retrieve list of schema names

URL

Responses

Sample request

Sample response

Retrieve list of table names in schema

URL

Responses

Sample request

Sample response

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