我想了解phoenix的查询执行计划。我正在执行下面的命令以获取查询执行计划。
命令：-

explain select "col1","col2", count(*) as "Count" from "tab_name" group by "col1","col2";

说明计划：-

+----------------------------------------------------------------------------------------------------------+
|                   PLAN                                                                                                     |
+----------------------------------------------------------------------------------------------------------+
|CLIENT 85-CHUNK PARALLEL 85-WAY FULL SCAN OVER tab_name                                                                                                                  |
|     SERVER AGGREGATE INTO DISTINCT ROWS BY [d."col1", d."col2"]  |
| CLIENT MERGE SORT                                                                                          |
+----------------------------------------------------------------------------------------------------------+

有谁能帮我理解Phoenix查询执行计划。
先谢谢你。