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Hudi External Table

Last updated: 2024-07-04 10:14:44
    Note:
    The content showcased in this document is only suitable for Tencent Cloud TCHouse-D v1.1 and below. For later versions, it is recommended to use the Multi-Catalog feature for interfacing with external data directories.
    The Hudi External Table of Doris provides Doris the capability to directly access Hudi external tables. This eliminates the tedious work of data importing, and leverages OLAP capabilities of Doris for data analysis in Hudi tables:
    1. Doris can access Hudi data source.
    2. Supports joint queries of table in Doris and Hive, the Hudi data source for more complex analysis.
    This document mainly introduces the usage and considerations of this feature.

    Usage

    Creating Hudi External Tables in Doris

    You can create Hudi external tables in Doris in the following two ways. There is no need to claim the definition of column when creating the table, for Doris can obtain column information from HiveMetaStore during query.
    1. Create an independent external table for mounting the Hudi table. For the related syntax, see CREATE TABLE.
    -- Syntax
    CREATE [EXTERNAL] TABLE table_name
    [(column_definition1[, column_definition2, ...])]
    ENGINE = HUDI
    [COMMENT "comment"]
    PROPERTIES (
    "hudi.database" = "hudi_db_in_hive_metastore",
    "hudi.table" = "hudi_table_in_hive_metastore",
    "hudi.hive.metastore.uris" = "thrift://127.0.0.1:9083"
    );
    
    -- Example: Mount the hudi_table_in_hive_metastore under the hudi_db_in_hive_metastore in HiveMetaStore. The schema is not specified during mounting.
    CREATE TABLE `t_hudi`
    ENGINE = HUDI
    PROPERTIES (
    "hudi.database" = "hudi_db_in_hive_metastore",
    "hudi.table" = "hudi_table_in_hive_metastore",
    "hudi.hive.metastore.uris" = "thrift://127.0.0.1:9083"
    );
    
    -- Example: Specify the schema during mounting
    CREATE TABLE `t_hudi` (
    `id` int NOT NULL COMMENT "id number",
    `name` varchar(10) NOT NULL COMMENT "user name"
    ) ENGINE = HUDI
    PROPERTIES (
    "hudi.database" = "hudi_db_in_hive_metastore",
    "hudi.table" = "hudi_table_in_hive_metastore",
    "hudi.hive.metastore.uris" = "thrift://127.0.0.1:9083"
    );

    Parameter description:

    External Table Column:
    The column name can be left unspecified. In this case, Doris will obtain the column information from HiveMetaStore during the query. This method of table creation is recommended.
    The name of the specified column must exist in the Hudi table.
    The ENGINE must be specified to HUDI.
    PROPERTIES attributes:
    hudi.hive.metastore.uris: The address for the Hive Metastore service.
    hudi.database: The name of the corresponding database when Hudi is mounted.
    hudi.table: The name of the corresponding table when Hudi is mounted.

    Display table structure

    You can view the table structure with SHOW CREATE TABLE peek .

    Type Matching

    The following table shows the corresponding relationships between supported Hudi column types and Doris:
    Hudi
    Doris
    Description
    BOOLEAN
    BOOLEAN
    -
    INTEGER
    INT
    -
    LONG
    BIGINT
    -
    FLOAT
    FLOAT
    -
    DOUBLE
    DOUBLE
    -
    DATE
    DATE
    -
    TIMESTAMP
    DATETIME
    Converting timestamp to datetime may cause loss of precision
    STRING
    STRING
    -
    UUID
    VARCHAR
    Use VARCHAR as a substitute
    DECIMAL
    DECIMAL
    -
    TIME
    -
    Not supported
    FIXED
    -
    Not supported
    BINARY
    -
    Not supported
    STRUCT
    -
    Not supported
    LIST
    -
    Not supported
    MAP
    -
    Not supported
    Note
    Currently, the supported Hudi version is 0.10.0 by default. Other versions haven't been tested.

    Query Usage

    You can use the Hudi external table in Doris the same way as using Doris OLAP tables, except that the Doris data models (Rollup, Pre-Aggregation, and Materialized Views, etc.) are unavailable.
    select * from t_hudi where k1 > 1000 and k3 ='term' or k4 like '%doris';
    
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