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lceberg Catalog

Last updated: 2024-07-04 10:18:23
    Mutil Catalog Iceberg offers Doris the capability of accessing external Iceberg tables directly without tedious data import tasks, and give full play to its inherent OLAP capability to perform data analysis on Iceberg tables:
    Iceberg data source can be connected to Doris.
    It enables joint queries across Doris and the Iceberg data source, and thus allows more complex analysis.
    This document mainly introduces how to use lceberg Catalog and preacautions during usage.
    Note:
    This feature is applicable to Tencent Cloud TCHouse-D 1.2 and later versions.
    Iceberg V1/V2 table formats are supported, with V2 only supporting the Position Delete method, not supporting Equality Delete.

    Creation Method

    Data on HDFS:
    CREATE RESOURCE ice_hms_resource PROPERTIES (
    'hive.metastore.uris' = 'thrift://172.16.xxxx:7004',
    'type' = 'hms',
    'dfs.nameservices'='HDFS1005116', 'dfs.ha.namenodes.HDFS1005116'='nn1,nn2',
    'dfs.namenode.rpc-address.HDFS1005116.nn1'='172.16.xxxx:4007',
    'dfs.namenode.rpc-address.HDFS1005116.nn2'='172.16.xxxx:4007',
    'dfs.client.failover.proxy.provider.HDFS1005116'='org.apache.hadoop.hdfs.server.namenode.ha.ConfiguredFailoverProxyProvider'
    );
    Data on COS:
    CREATE CATALOG hive_cossab PROPERTIES ( "AWS_ENDPOINT" = "cos.ap-guangzhou.myqcloud.com", "AWS_REGION" = "ap-guangzhou", "AWS_SECRET_KEY" = "Wu9ByN6g4D8seHj0770jxxxxxxx", "use_path_style" = "true", "hive.metastore.uris" = "thrift://172.16.xxxx:7004", "type" = "hms", "AWS_ACCESS_KEY" = "AKIDaWJcCi9Rc4TqjV9hYHn9Nxxxxxxxxx" );

    Type Matching

    Supported column type of Iceberg corresponds to Doris as follows:
    HMS Type
    Doris Type
    Comment
    boolean
    boolean
     -
    tinyint
    tinyint
     -
    smallint
    smallint
     -
    int
    int
     -
    bigint
    bigint
     -
    date
    date
     -
    timestamp
    datetime
     -
    float
    float
     -
    double
    double
     -
    char
    char
     -
    varchar
    varchar
     -
    decimal
    decimal
     -
    array<type>
    array<type>
    Nested arrays, such as array<array<int>>, are supported.
    map<KeyType, ValueType>
    map<KeyType, ValueType>
    Nested structure is not supported; KeyType and ValueType must be basic types.
    struct<col1: Type1, col2: Type2, ...>
    struct<col1: Type1, col2: Type2, ...>
    Nested structure is not supported; Type1, Type2, ... must be basic types.
    other
    unsupported
     -

    Time Travel

    Reading a specified Snapshot from the Iceberg table is supported.
    Every write operation on the Iceberg table will produce a new snapshot.
    By default, read requests only read the snapshot of the latest version.
    You can use the FOR TIME AS OF and FOR VERSION AS OF statements to read historical version data based on the snapshot ID or the time when the snapshot was generated as shown in the following examples:
    SELECT * FROM iceberg_tbl FOR TIME AS OF "2022-10-07 17:20:37";
    SELECT * FROM iceberg_tbl FOR VERSION AS OF 868895038966572;

    Query Usage

    There is no difference from ordinary Doris OLAP tables.
    select * from ice_catalog_name.database_name.table_name;
    
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