is there any metadata store like 'hive metastore' in BigQuery?

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滥情空心 2021-01-03 09:45

I am new to BigQuery. I just want to know, whether do we have anything like hive metastore (metadata about all tables, columns and their description) in BigQuery?

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  •  执笔经年
    2021-01-03 10:15

    BigQuery offers some special tables whose contents represent metadata, such as the list of tables and views in a dataset. The "meta-tables" are read-only. To access metadata about the tables and views in a dataset, use the __TABLES_SUMMARY__ meta-table in a query's SELECT statement. You can run the query using the BigQuery web UI, using the command-line tool's bq query command, or by calling the jobs.insert API method and configuring a query job.

    Another more detailed meta-table is __TABLES__ - see example below

        SELECT table_id,
            DATE(TIMESTAMP_MILLIS(creation_time)) AS creation_date,
            DATE(TIMESTAMP_MILLIS(last_modified_time)) AS last_modified_date,
            row_count,
            size_bytes,
            CASE
                WHEN type = 1 THEN 'table'
                WHEN type = 2 THEN 'view'
                WHEN type = 3 THEN 'external'
                ELSE '?'
            END AS type,
            TIMESTAMP_MILLIS(creation_time) AS creation_time,
            TIMESTAMP_MILLIS(last_modified_time) AS last_modified_time,
            dataset_id,
            project_id
        FROM `project.dataset.__TABLES__`  
    

    for table schema - columns, description - you can utilize bq command line - for example:

    bq show publicdata:samples.shakespeare  
    

    with result as

     tableId      Last modified                  Schema
     ------------- ----------------- ------------------------------------
     shakespeare   01 Sep 13:46:28   |- word: string (required)
                                     |- word_count: integer (required)
                                     |- corpus: string (required)
                                     |- corpus_date: integer (required)
    

    see more at https://cloud.google.com/bigquery/bq-command-line-tool#gettable

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