有没有办法在Redshift中复制或克隆表之间的授权？

Question

由于Redshift的仅附加属性，我们经常需要合并表以删除重复记录并显示最新版本的记录。要准备此过程，将重命名基表并创建其副本。将执行脚本以扫描插入表并将最新的唯一记录移动到新的基表中。但是，如果表在此过程开始之前已经运行了一段时间，那么在创建克隆时，表上可能会有未授权的授权。

我们经常没有原始表DDL，虽然我们能够通过https://github.com/awslabs/amazon-redshift-utils/blob/master/src/AdminViews/v_generate_tbl_ddl.sql获取它，但这不会生成任何授权的表定义。

有没有办法复制具有就地授予的表，或生成一个脚本来创建基于旧表的授权？

尝试过使用https://github.com/awslabs/amazon-redshift-utils/blob/master/src/AdminViews/v_generate_tbl_ddl.sql，但这不会生成任何grant语句，只会生成set owner语句。

也看了has_table_privilege，但这似乎不是最简单的行动方案。

Answer 1

我不想将此标记为答案，因为我确信有人有更好的方法，但我能够编写一个脚本来查看两个表之间的读权限差异并生成grant语句：

SELECT
    'GRANT SELECT ON TABLE ' || admin_table.schemaname || '.' || admin_table.objectname || ' to ' || old_table.usename || ';' AS grant_statement
FROM (
    SELECT *
    FROM (
        SELECT
            schemaname
            ,objectname
            ,usename
            ,has_table_privilege(usrs.usename, fullobj, 'select') AND has_schema_privilege(usrs.usename, schemaname, 'usage')  AS sel
        FROM (
            SELECT schemaname, 't' AS obj_type, tablename AS objectname, schemaname + '.' + tablename AS fullobj FROM pg_tables
            UNION
            SELECT schemaname, 'v' AS obj_type, viewname AS objectname, schemaname + '.' + viewname AS fullobj FROM pg_views
        ) AS objs
        , (SELECT * FROM pg_user) AS usrs
        ORDER BY fullobj
    )
    WHERE (sel = true)
    AND schemaname = '{schema_name}' AND objectname = '{old_table_name}') AS old_table
    FULL OUTER JOIN (
        SELECT *
        FROM (
            SELECT
                schemaname
                ,objectname
                ,usename
                ,has_table_privilege(usrs.usename, fullobj, 'select') AND has_schema_privilege(usrs.usename, schemaname, 'usage')  AS sel
            FROM (
                SELECT schemaname, 't' AS obj_type, tablename AS objectname, schemaname + '.' + tablename AS fullobj FROM pg_tables
                UNION
                SELECT schemaname, 'v' AS obj_type, viewname AS objectname, schemaname + '.' + viewname AS fullobj FROM pg_views
            ) AS objs
            , (SELECT * FROM pg_user) AS usrs
            ORDER BY fullobj
        )
        WHERE (sel = true)
        AND schemaname = '{schema_name}' AND objectname = '{new_table_name}') AS new_table
            ON old_table.schemaname = new_table.schemaname
            AND old_table.sel = new_table.sel
            AND old_table.usename = new_table.usename
    JOIN (
        SELECT *
        FROM (
            SELECT
                schemaname
                ,objectname
                ,usename
                ,has_table_privilege(usrs.usename, fullobj, 'select') AND has_schema_privilege(usrs.usename, schemaname, 'usage')  AS sel
            FROM (
                SELECT schemaname, 't' AS obj_type, tablename AS objectname, schemaname + '.' + tablename AS fullobj FROM pg_tables
                UNION
                SELECT schemaname, 'v' AS obj_type, viewname AS objectname, schemaname + '.' + viewname AS fullobj FROM pg_views
            ) AS objs
            , (SELECT * FROM pg_user) AS usrs
            ORDER BY fullobj
        )
        WHERE (sel = true)
        AND schemaname = '{schema_name}' AND objectname = '{new_table_name}') AS admin_table
            ON admin_table.usename = '{admin_user}'
    WHERE new_table.usename IS NULL
    AND old_table.sel IS true;```