使用 HCatalog 连接器查询 Hive 表

定义 HCatalog 架构后，您就可以通过在查询中使用该架构名称，来查询 Hive 数据库中的数据。

=> SELECT * from hcat.messages limit 10;
 messageid |   userid   |        time         |             message
-----------+------------+---------------------+----------------------------------
         1 | nPfQ1ayhi  | 2013-10-29 00:10:43 | hymenaeos cursus lorem Suspendis
         2 | N7svORIoZ  | 2013-10-29 00:21:27 | Fusce ad sem vehicula morbi
         3 | 4VvzN3d    | 2013-10-29 00:32:11 | porta Vivamus condimentum
         4 | heojkmTmc  | 2013-10-29 00:42:55 | lectus quis imperdiet
         5 | coROws3OF  | 2013-10-29 00:53:39 | sit eleifend tempus a aliquam mauri
         6 | oDRP1i     | 2013-10-29 01:04:23 | risus facilisis sollicitudin sceler
         7 | AU7a9Kp    | 2013-10-29 01:15:07 | turpis vehicula tortor
         8 | ZJWg185DkZ | 2013-10-29 01:25:51 | sapien adipiscing eget Aliquam tor
         9 | E7ipAsYC3  | 2013-10-29 01:36:35 | varius Cum iaculis metus
        10 | kStCv      | 2013-10-29 01:47:19 | aliquam libero nascetur Cum mal
(10 rows)

由于您通过 HCatalog 连接器访问的表的行为就像 Vertica 表一样，您可以执行同时使用 Hive 数据和原生 Vertica 数据的操作，如 join：

=> SELECT u.FirstName, u.LastName, d.time, d.Message from UserData u
-> JOIN hcat.messages d ON u.UserID = d.UserID LIMIT 10;
FirstName | LastName |        time         |                  Message
----------+----------+---------------------+-----------------------------------
Whitney   | Kerr     | 2013-10-29 00:10:43 | hymenaeos cursus lorem Suspendis
Troy      | Oneal    | 2013-10-29 00:32:11 | porta Vivamus condimentum
Renee     | Coleman  | 2013-10-29 00:42:55 | lectus quis imperdiet
Fay       | Moss     | 2013-10-29 00:53:39 | sit eleifend tempus a aliquam mauri
Dominique | Cabrera  | 2013-10-29 01:15:07 | turpis vehicula tortor
Mohammad  | Eaton    | 2013-10-29 00:21:27 | Fusce ad sem vehicula morbi
Cade      | Barr     | 2013-10-29 01:25:51 | sapien adipiscing eget Aliquam tor
Oprah     | Mcmillan | 2013-10-29 01:36:35 | varius Cum iaculis metus
Astra     | Sherman  | 2013-10-29 01:58:03 | dignissim odio Pellentesque primis
Chelsea   | Malone   | 2013-10-29 02:08:47 | pede tempor dignissim Sed luctus
(10 rows)