eXtremeDB相关问题解答(4)

 

1.      联合索引包含的字段是否需要单独创建索引，什么时候需要单独创建

符合索引Index on A B C

                  对于单独索引，字段A不用创建；如果检索B和C，需要创建单独索引。

2.      最佳散列表的创建

A:散列表创建的支持可以通过

(type=Database.IndexType.Hashtable, unique=true) -----------createsa hash index

(initSize=N)       ----------- for ahash index, where N is the initial size of the hash table

 

3.      监控界面java如何开启

A:可以直接通过我们的IE界面查看数据库相关信息。eXtremeDB\win64vs2010\samples\native\core\22-httpview

 

4.      如何查看数据库的执行计划及时间；

通过\eXtremeDB\win64vs2010\samples\native\sql\xsql编译后，可以执行xsql(DATABASE_NAME | @HOST)[:PORT | :*]

形如：

XSQL>traceon

XSQL>select* from S;

Executestatement: select * from S

sid    sname   status  dat    city    keywords       autoid

------------------------------------------------------------------------------

S4     SN4     4       01/01/7008:00:00              []      15

S3     SN3     3       01/01/7008:00:00              []      14

S2     SN2     2       01/01/7008:00:00              []      13

S1     SN1     1       01/01/7008:00:00              []      12

S0     SN0     0       01/01/7008:00:00              []      11

S5     SN5     5       01/01/7008:00:00              []      16

S9     SN9     9       01/01/7008:00:00              []      20

S8     SN8     8       01/01/7008:00:00              []     19

S7     SN7     7       01/01/7008:00:00              []      18

S6     SN6     6       01/01/7008:00:00              []      17

 

Selectedrecords: 10

Elapsedtime: 0

XSQL>select* from S where sid='S5';

Executestatement: select * from S where sid='S5'

Hashindex search through table 'S' < sid >

       expression: (Eq (Column 1) S5)

sid    sname   status  dat    city    keywords       autoid

------------------------------------------------------------------------------

S5     SN5    5       01/01/7008:00:00              []      16

 

Selectedrecords: 1

Elapsedtime: 31

XSQL>help