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Apache Pinot Connector

presto-docs/src/main/sphinx/connector/pinot.rst

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====================== Apache Pinot Connector

The Apache Pinot connector allows querying and creating tables in an external Apache Pinot database. This can be used to query pinot data or join pinot data with something else.

Configuration

To configure the Pinot connector, create a catalog properties file in etc/catalog named, for example, pinot.properties, to mount the Pinot connector as the pinot catalog. Create the file with the following contents, replacing the connection properties as appropriate for your setup:

.. code-block:: none

connector.name=pinot
pinot.controller-urls=controller_host1:9000,controller_host2:9000

Where the pinot.controller-urls property allows you to specify a comma separated list of the pinot controller host/port pairs.

Multiple Pinot Clusters ^^^^^^^^^^^^^^^^^^^^^^^

You can have as many catalogs as you need, so if you have additional Pinot clusters, simply add another properties file to etc/catalog with a different name (making sure it ends in .properties). For example, if you name the property file sales.properties, Presto will create a catalog named sales using the configured connector.

Catalog Properties ^^^^^^^^^^^^^^^^^^

The following catalog configuration properties are available:

========================================================== ============================================================================================================= Property Name Description ========================================================== ============================================================================================================= pinot.controller-urls Pinot controller urls. pinot.controller-rest-service Alternative rest endpoint for Pinot controller requests. pinot.rest-proxy-url Pinot rest proxy url. pinot.limit-large-for-segment Cap the number of rows returned when pushing down non-aggregation segment query, default is 2147483647. pinot.topn-large Cap the TOP/LIMIT value when pushing down broker query, default is 10000. pinot.connection-timeout Connection Timeout to talk to Pinot servers, default is 1 minute. pinot.metadata-expiry Pinot metadata cache expiration time, default is 2 minutes. pinot.estimated-size-in-bytes-for-non-numeric-column Estimated byte size for non-numeric column, default is 20. pinot.service-header-param RPC service header key, default is "RPC-Service". pinot.caller-header-param RPC service caller header key, default is "RPC-Caller". pinot.caller-header-value RPC service caller header value, default is "presto". pinot.forbid-broker-queries No broker request pushing down, default is false. pinot.forbid-segment-queries No segment query pushing down, fail the query if broker query pushing down is not possible, default is false. pinot.rest-proxy-service-for-query Use rest proxy endpoint for Pinot broker requests, default is false. pinot.use-date-trunc Use the new UDF dateTrunc in pinot that is more presto compatible, default is false. pinot.num-segments-per-split Number of segments of the same host per split, default is 1. pinot.ignore-empty-responses Ignore empty or missing pinot server responses, default is false. pinot.fetch-retry-count Retry count for retriable pinot data fetch calls, default is 2. pinot.non-aggregate-limit-for-broker-queries Max limit for non aggregate queries to the pinot broker, default is 25000. pinot.infer-date-type-in-schema Infer Pinot DAYS epoch column to Presto DATE type, default is true. pinot.infer-timestamp-type-in-schema Infer Pinot SECONDS epoch column to Presto TIMESTAMP type, default is true. pinot.mark-data-fetch-exceptions-as-retriable Retry Pinot request when failure, default is true. pinot.pushdown-topn-broker-queries Allow pushing down query pattern to broker: aggregation + groupBy + orderBy, default is false. pinot.streaming-server-grpc-max-inbound-message-bytes Max inbound message bytes when init gRPC client, default is 128MB. pinot.proxy-enabled Pinot Cluster is behind a proxy, default is false. pinot.grpc-host Pinot gRPC host. pinot.grpc-port Pinot gRPC port. pinot.secure-connection Use https for all connections is false. pinot.override-distinct-count-function Override 'distinctCount' function name, default is "distinctCount". pinot.extra-http-headers Extra headers when sending HTTP based pinot requests to Pinot controller/broker. E.g. k1:v1,k2:v2. pinot.extra-grpc-metadata Extra metadata when sending gRPC based pinot requests to Pinot broker/server/proxy. E.g. k1:v1,k2:v2. pinot.grpc-tls-key-store-path TLS keystore file location for gRPC connection, default is empty (not needed) pinot.grpc-tls-key-store-type TLS keystore type for gRPC connection, default is empty (not needed) pinot.grpc-tls-key-store-password TLS keystore password, default is empty (not needed) pinot.grpc-tls-trust-store-path TLS truststore file location for gRPC connection, default is empty (not needed) pinot.grpc-tls-trust-store-type TLS truststore type for gRPC connection, default is empty (not needed) pinot.grpc-tls-trust-store-password TLS truststore password, default is empty (not needed) pinot.controller-authentication-type Pinot authentication method for controller requests. Allowed values are NONE and PASSWORD - defaults to NONE which is no authentication. pinot.controller-authentication-user Controller username for basic authentication method. pinot.controller-authentication-password Controller password for basic authentication method. pinot.broker-authentication-type Pinot authentication method for broker requests. Allowed values are NONE and PASSWORD - defaults to NONE which is no authentication. pinot.broker-authentication-user Broker username for basic authentication method. pinot.broker-authentication-password Broker password for basic authentication method. pinot.query-options Pinot query-related case-sensitive options. E.g. skipUpsert:true,enableNullHandling:true case-sensitive-name-matching Enable case-sensitive identifier support for schema, table, and column names for the connector. When disabled, names are matched case-insensitively using lowercase normalization. Default is false. ========================================================== =============================================================================================================

If pinot.controller-authentication-type is set to PASSWORD then both pinot.controller-authentication-user and pinot.controller-authentication-password are required.

If pinot.broker-authentication-type is set to PASSWORD then both pinot.broker-authentication-user and pinot.broker-authentication-password are required.

Session Properties ^^^^^^^^^^^^^^^^^^

The following session properties are available:

======================================================== ================================================================== Property Name Description ======================================================== ================================================================== pinot.forbid_broker_queries Forbid queries to the broker. pinot.forbid_segment_queries Forbid segment queries. pinot.mark_data_fetch_exceptions_as_retriable Retry Pinot query on data fetch exceptions. pinot.retry_count Retry count for retriable pinot data fetch calls. pinot.use_date_trunc Use the new UDF dateTrunc in pinot that is more presto compatible. pinot.non_aggregate_limit_for_broker_queries Max limit for non aggregate queries to the pinot broker. pinot.pushdown_topn_broker_queries Push down order by to pinot broker for top queries. pinot.num_segments_per_split Number of segments of the same host per split. pinot.limit_larger_for_segment Server query selection limit for large segment. pinot.override_distinct_count_function Override distinct count function to another function name. pinot.topn_large Cap the TOP/LIMIT value when pushing down broker query. pinot.controller_authentication_user Controller username for basic authentication method. pinot.controller_authentication_password Controller password for basic authentication method. pinot.broker_authentication_user Broker username for basic authentication method. pinot.broker_authentication_password Broker password for basic authentication method. pinot.query_options Pinot query-related case-sensitive options. E.g. skipUpsert:true,enableNullHandling:true ======================================================== ==================================================================

Map Pinot Schema to Presto Schema

In general Pinot schema to Presto schema mapping are pretty straight forward. By default, the data type mapping follows the table below.

.. list-table:: :widths: 100 100 :header-rows: 1

    • Pinot Data Type
    • Presto Data Type
    • INT
    • INTEGER
    • LONG
    • BIGINT
    • FLOAT
    • DOUBLE
    • DOUBLE
    • DOUBLE
    • BYTES
    • VARBINARY
    • STRING
    • VARCHAR

Since Pinot defines each field as dimension, metric or time(date_time) field, it's possible to infer Presto data type DATE and TIMESTAMP:

  • A Pinot TIME field with timeGranularity { "TimeFormat":"EPOCH", "TimeUnit":"DAYS", "TimeUnitSize": 1 } could be map to a DATE type.
  • A Pinot TIME field with timeGranularity { "TimeFormat":"EPOCH", "TimeUnit":"MILLISECONDS", "TimeUnitSize": 1 } could be map to a TIMESTAMP type.
  • A Pinot DATE_TIME field with format 1:DAYS:EPOCH could be map to a DATE type.
  • A Pinot DATE_TIME field with format 1:MILLISECONDS:EPOCH could be map to a TIMESTAMP type.

There are a few configurations that control this behavior:

  • pinot.infer-date-type-in-schema: This config is false by default. Setting it to true will infer a Pinot TIME/DATE_TIME field to DATE in Presto if possible.

  • pinot.infer-timestamp-type-in-schema: This config is false by default. Setting it to true will infer a Pinot TIME/DATE_TIME field to TIMESTAMP in Presto if possible.

Below is an example with config: pinot.infer-timestamp-type-in-schema=true.

Sample Pinot Schema:

.. code-block:: JSON

{ "schemaName": "meetupRsvp", "dimensionFieldSpecs": [ { "name": "venue_name", "dataType": "STRING" }, { "name": "event_name", "dataType": "STRING" }, { "name": "event_id", "dataType": "STRING" }, { "name": "event_time", "dataType": "LONG" }, { "name": "group_city", "dataType": "STRING" }, { "name": "group_country", "dataType": "STRING" }, { "name": "group_id", "dataType": "LONG" }, { "name": "group_name", "dataType": "STRING" } ], "metricFieldSpecs": [ { "name": "rsvp_count", "dataType": "INT" } ], "timeFieldSpec": { "incomingGranularitySpec": { "name": "mtime", "dataType": "LONG", "timeType": "MILLISECONDS" } } }

Sample Presto Schema:

.. code-block:: none

table_catalog | table_schema | table_name | column_name | ordinal_position | column_default | is_nullable | data_type | comment | extra_info ---------------+--------------+------------+---------------+------------------+----------------+-------------+-----------+-----------+------------ pinot | default | meetuprsvp | venue_name | 1 | NULL | YES | varchar | DIMENSION | NULL pinot | default | meetuprsvp | rsvp_count | 2 | NULL | YES | integer | METRIC | NULL pinot | default | meetuprsvp | group_city | 3 | NULL | YES | varchar | DIMENSION | NULL pinot | default | meetuprsvp | event_id | 4 | NULL | YES | varchar | DIMENSION | NULL pinot | default | meetuprsvp | group_country | 5 | NULL | YES | varchar | DIMENSION | NULL pinot | default | meetuprsvp | group_id | 6 | NULL | YES | bigint | DIMENSION | NULL pinot | default | meetuprsvp | group_name | 7 | NULL | YES | varchar | DIMENSION | NULL pinot | default | meetuprsvp | event_name | 8 | NULL | YES | varchar | DIMENSION | NULL pinot | default | meetuprsvp | mtime | 9 | NULL | YES | timestamp | TIME | NULL pinot | default | meetuprsvp | event_time | 10 | NULL | YES | bigint | DIMENSION | NULL

Querying Pinot

The Pinot catalog exposes all pinot tables inside a flat schema. The schema name is immaterial when querying but running SHOW SCHEMAS, will show just one schema entry of default.

The name of the pinot catalog is the catalog file you created above without the .properties extension.

For example, if you created a file called mypinotcluster.properties, you can see all the tables in it using the command::

SHOW TABLES from mypinotcluster.default

OR::

SHOW TABLES from mypinotcluster.foo

Both of these commands will list all the tables in your pinot cluster. This is because Pinot does not have a notion of schemas.

Consider you have a table called clicks in the mypinotcluster. You can see a list of the columns in the clicks table using either of the following::

DESCRIBE mypinotcluster.dontcare.clicks;
SHOW COLUMNS FROM mypinotcluster.dontcare.clicks;

Finally, you can access the clicks table::

SELECT count(*) FROM mypinotcluster.default.clicks;

How the Apache Pinot connector works

The connector tries to push the maximal sub-query inferred from the presto query into pinot. It can push down everything Pinot supports including aggregations, group by, all UDFs etc. It generates the correct Pinot query keeping Pinot's quirks in mind.

By default, it sends aggregation and limit queries to the Pinot broker and does a parallel scan for non-aggregation/non-limit queries. The pinot broker queries create a single split that lets the Pinot broker do the scatter gather. Whereas, in the parallel scan mode, there is one split created for one-or-more Pinot segments and the Pinot servers are directly contacted by the Presto servers (ie., the Pinot broker is not involved in the parallel scan mode)

There are a few configurations that control this behavior:

  • pinot.prefer-broker-queries: This config is true by default. Setting it to false will also create parallel plans for aggregation and limit queries.
  • pinot.forbid-segment-queries: This config is false by default. Setting it to true will forbid parallel querying and force all querying to happen via the broker.
  • pinot.non-aggregate-limit-for-broker-queries: To prevent overwhelming the broker, the connector only allows querying the pinot broker for short queries. We define a short query to be either an aggregation (or group-by) query or a query with a limit less than the value configured for pinot.non-aggregate-limit-for-broker-queries. The default value for this limit is 25K rows.