Elasticsearch connector#

The Elasticsearch Connector allows access to Elasticsearch data from Trino. This document describes how to setup the Elasticsearch Connector to run SQL queries against Elasticsearch.

Note

Elasticsearch (6.6.0 or later) or OpenSearch (1.1.0 or later) is required.

Configuration#

To configure the Elasticsearch connector, create a catalog properties file etc/catalog/elasticsearch.properties with the following contents, replacing the properties as appropriate:

connector.name=elasticsearch
elasticsearch.host=localhost
elasticsearch.port=9200
elasticsearch.default-schema-name=default

Configuration properties#

Elasticsearch configuration properties#
Property name	Description	Default
`elasticsearch.host`	Hostname of the Elasticsearch node to connect to. This property is required.
`elasticsearch.port`	Port of the Elasticsearch node to connect to.	`9200`
`elasticsearch.default-schema-name`	The schema that contains all tables defined without a qualifying schema name.	`default`
`elasticsearch.scroll-size`	Sets the maximum number of hits that can be returned with each Elasticsearch scroll request.	`1000`
`elasticsearch.scroll-timeout`	Amount of time Elasticsearch keeps the search context alive for scroll requests.	`1m`
`elasticsearch.request-timeout`	Timeout value for all Elasticsearch requests.	`10s`
`elasticsearch.connect-timeout`	Timeout value for all Elasticsearch connection attempts.	`1s`
`elasticsearch.backoff-init-delay`	The minimum duration between backpressure retry attempts for a single request to Elasticsearch. Setting it too low might overwhelm an already struggling ES cluster.	`500ms`
`elasticsearch.backoff-max-delay`	The maximum duration between backpressure retry attempts for a single request to Elasticsearch.	`20s`
`elasticsearch.max-retry-time`	The maximum duration across all retry attempts for a single request to Elasticsearch.	`20s`
`elasticsearch.node-refresh-interval`	How often the list of available Elasticsearch nodes is refreshed.	`1m`
`elasticsearch.ignore-publish-address`	Disables using the address published by Elasticsearch to connect for queries.
`elasticsearch.legacy-pass-through-query.enabled`	Enables legacy pass-through query	false

TLS security#

The Elasticsearch connector provides additional security options to support Elasticsearch clusters that have been configured to use TLS.

If your cluster has globally-trusted certificates, you should only need to enable TLS. If you require custom configuration for certificates, the connector supports key stores and trust stores in PEM or Java Key Store (JKS) format.

The allowed configuration values are:

TLS Security Properties#
Property name	Description
`elasticsearch.tls.enabled`	Enables TLS security.
`elasticsearch.tls.keystore-path`	The path to the PEM or JKS key store. This file must be readable by the operating system user running Trino.
`elasticsearch.tls.truststore-path`	The path to PEM or JKS trust store. This file must be readable by the operating system user running Trino.
`elasticsearch.tls.keystore-password`	The key password for the key store specified by `elasticsearch.tls.keystore-path`.
`elasticsearch.tls.truststore-password`	The key password for the trust store specified by `elasticsearch.tls.truststore-path`.

Type mapping#

Because Trino and Elasticsearch each support types that the other does not, this connector maps some types when reading data.

Elasticsearch type to Trino type mapping#

The connector maps Elasticsearch types to the corresponding Trino types according to the following table:

Elasticsearch type to Trino type mapping#
Elasticsearch type	Trino type	Notes
`BOOLEAN`	`BOOLEAN`
`DOUBLE`	`DOUBLE`
`FLOAT`	`REAL`
`BYTE`	`TINYINT`
`SHORT`	`SMALLINT`
`INTEGER`	`INTEGER`
`LONG`	`BIGINT`
`KEYWORD`	`VARCHAR`
`TEXT`	`VARCHAR`
`DATE`	`TIMESTAMP`	For more information, see Date types.
`IPADDRESS`	`IP`

No other types are supported.

Array types#

Fields in Elasticsearch can contain zero or more values , but there is no dedicated array type. To indicate a field contains an array, it can be annotated in a Trino-specific structure in the _meta section of the index mapping.

For example, you can have an Elasticsearch index that contains documents with the following structure:

{
    "array_string_field": ["trino","the","lean","machine-ohs"],
    "long_field": 314159265359,
    "id_field": "564e6982-88ee-4498-aa98-df9e3f6b6109",
    "timestamp_field": "1987-09-17T06:22:48.000Z",
    "object_field": {
        "array_int_field": [86,75,309],
        "int_field": 2
    }
}

The array fields of this structure can be defined by using the following command to add the field property definition to the _meta.trino property of the target index mapping.

curl --request PUT \
    --url localhost:9200/doc/_mapping \
    --header 'content-type: application/json' \
    --data '
{
    "_meta": {
        "trino":{
            "array_string_field":{
                "isArray":true
            },
            "object_field":{
                "array_int_field":{
                    "isArray":true
                }
            },
        }
    }
}'

Note

It is not allowed to use asRawJson and isArray flags simultaneously for the same column.

Date types#

Elasticsearch supports a wide array of date formats including built-in date formats and also custom date formats. The Elasticsearch connector supports only the default date type. All other date formats including built-in date formats and custom date formats are not supported. Dates with the format property are ignored.

Raw JSON transform#

There are many occurrences where documents in Elasticsearch have more complex structures that are not represented in the mapping. For example, a single keyword field can have widely different content including a single keyword value, an array, or a multidimensional keyword array with any level of nesting.

curl --request PUT \
    --url localhost:9200/doc/_mapping \
    --header 'content-type: application/json' \
    --data '
{
    "properties": {
        "array_string_field":{
            "type": "keyword"
        }
    }
}'

Notice for the array_string_field that all the following documents are legal for Elasticsearch. See the Elasticsearch array documentation for more details.

[
    {
        "array_string_field": "trino"
    },
    {
        "array_string_field": ["trino","is","the","besto"]
    },
    {
        "array_string_field": ["trino",["is","the","besto"]]
    },
    {
        "array_string_field": ["trino",["is",["the","besto"]]]
    }
]

Further, Elasticsearch supports types, such as dense_vector, that are not supported in Trino. New types are constantly emerging which can cause parsing exceptions for users that use of these types in Elasticsearch. To manage all of these scenarios, you can transform fields to raw JSON by annotating it in a Trino-specific structure in the _meta section of the index mapping. This indicates to Trino that the field, and all nested fields beneath, need to be cast to a VARCHAR field that contains the raw JSON content. These fields can be defined by using the following command to add the field property definition to the _meta.presto property of the target index mapping.

curl --request PUT \
    --url localhost:9200/doc/_mapping \
    --header 'content-type: application/json' \
    --data '
{
    "_meta": {
        "presto":{
            "array_string_field":{
                "asRawJson":true
            }
        }
    }
}'

This preceding configurations causes Trino to return the array_string_field field as a VARCHAR containing raw JSON. You can parse these fields with the built-in JSON functions.

Note

It is not allowed to use asRawJson and isArray flags simultaneously for the same column.

Special columns#

The following hidden columns are available:

Column	Description
_id	The Elasticsearch document ID
_score	The document score returned by the Elasticsearch query
_source	The source of the original document

Full text queries#

Trino SQL queries can be combined with Elasticsearch queries by providing the full text query as part of the table name, separated by a colon. For example:

SELECT * FROM "tweets: +trino SQL^2"

Predicate push down#

The connector supports predicate push down of below data types:

Elasticsearch	Trino	Supports
`binary`	`VARBINARY`	`NO`
`boolean`	`BOOLEAN`	`YES`
`double`	`DOUBLE`	`YES`
`float`	`REAL`	`YES`
`byte`	`TINYINT`	`YES`
`short`	`SMALLINT`	`YES`
`integer`	`INTEGER`	`YES`
`long`	`BIGINT`	`YES`
`keyword`	`VARCHAR`	`YES`
`text`	`VARCHAR`	`NO`
`date`	`TIMESTAMP`	`YES`
`ip`	`IPADDRESS`	`NO`
(all others)	(unsupported)	(unsupported)

Pass-through queries#

Note

This feature is deprecated and disabled by default. It’s recommended to use raw_query table function instead. To enable legacy pass-through query please use elasticsearch.legacy-pass-through-query-enabled configuration property.

The Elasticsearch connector allows you to embed any valid Elasticsearch query, that uses the Elasticsearch Query DSL in your SQL query.

The results can then be used in any SQL statement, wrapping the Elasticsearch query. The syntax extends the syntax of the enhanced Elasticsearch table names with the following:

SELECT * FROM es.default."<index>$query:<es-query>"

The Elasticsearch query string es-query is base32-encoded to avoid having to deal with escaping quotes and case sensitivity issues in table identifiers.

The result of these query tables is a table with a single row and a single column named result of type VARCHAR. It contains the JSON payload returned by Elasticsearch, and can be processed with the built-in JSON functions.

AWS authorization#

To enable AWS authorization using IAM policies, the elasticsearch.security option needs to be set to AWS. Additionally, the following options need to be configured appropriately:

Property name	Description
`elasticsearch.aws.region`	AWS region or the Elasticsearch endpoint. This option is required.
`elasticsearch.aws.access-key`	AWS access key to use to connect to the Elasticsearch domain. If not set, the Default AWS Credentials Provider chain will be used.
`elasticsearch.aws.secret-key`	AWS secret key to use to connect to the Elasticsearch domain. If not set, the Default AWS Credentials Provider chain will be used.
`elasticsearch.aws.iam-role`	Optional ARN of an IAM Role to assume to connect to the Elasticsearch domain. Note: the configured IAM user has to be able to assume this role.
`elasticsearch.aws.external-id`	Optional external ID to pass while assuming an AWS IAM Role.

Password authentication#

To enable password authentication, the elasticsearch.security option needs to be set to PASSWORD. Additionally the following options need to be configured appropriately:

Property name	Description
`elasticsearch.auth.user`	User name to use to connect to Elasticsearch.
`elasticsearch.auth.password`	Password to use to connect to Elasticsearch.

SQL support#

The connector provides globally available and read operation statements to access data and metadata in the Elasticsearch catalog.