分区表查询时，根据查询条件，自动过滤掉未命中的分区，只在命中的分区中查询
使用优化方法分区表查询SQL的WHERE条件或者经GBase 8a MPP Cluster整理后的WHERE条件符合以下两种情况，即可应用分区筛选：
partition_name = constantpartition_name IN (constant1, constant2,……)WHERE条件可以涵盖：<、<=、>、>=、 =、 <>、IN、BETWEEN...AND...等。
示例:
gbase> CREATE TABLE t1 (n INT) PARTITION BY RANGE(n)
-> (
-> PARTITION p0 VALUES LESS THAN (100),
-> PARTITION p1 VALUES LESS THAN (200),
-> PARTITION p2 VALUES LESS THAN (300),
-> PARTITION p3 VALUES LESS THAN (400)
-> );
Query OK, 0 rows affected (Elapsed: 00:00:00.13)
gbase> INSERT INTO t1 VALUES(1),(2),(3),(4),(5);
Query OK, 5 rows affected (Elapsed: 00:00:00.10)Records: 5Duplicates: 0 Warnings: 0
gbase> INSERT INTO t1 VALUES(101),(102),(103),(104),(105);
Query OK, 5 rows affected (Elapsed: 00:00:00.08)Records: 5Duplicates: 0 Warnings: 0
gbase> INSERT INTO t1 VALUES(201),(202),(203),(204),(205);
Query OK, 5 rows affected (Elapsed: 00:00:00.10)Records: 5Duplicates: 0 Warnings: 0
gbase> INSERT INTO t1 VALUES(301),(302),(303),(304),(305);
Query OK, 5 rows affected (Elapsed: 00:00:00.09)Records: 5Duplicates: 0 Warnings: 0
gbase> SELECT * from t1 WHERE n <4;
+------+
| n |
+------+
|1 |
|2 |
|3 |
+------+
3 rows in set (Elapsed: 00:00:00.05)
gbase> SELECT * from t1 WHERE n >300;
+------+
| n |
+------+
|301 |
|302 |
|303 |
|304 |
|305 |
+------+
5 rows in set (Elapsed: 00:00:00.03)
gbase> SELECT * FROM t1 WHERE n IN (101,309);
+------+
| n5 数据库管理指南|
+------+
|101 |
+------+
1 row in set (Elapsed: 00:00:00.04)
gbase> SELECT * FROM t1 WHERE n BETWEEN 1 AND 199;
+------+
| n |
+------+
|1 |
|2 |
|3 |
|4 |
|5 |
|101 |
|102 |
|103 |
|104 |
|105 |
+------+
10 rows in set (Elapsed: 00:00:00.05)
