C M P   2 . 0  

Tag Name 

Description 

Required 

datasource 

This specifies the name of the type mapping, which 

No, default is 

mapping 

determines how Java types are mapped to SQL types, and 

Hypersonic 

how EJB QL functions are mapped to database specific 

SQL 

functions. Type mapping is discussed in Appendix C of the 

JBossCMP Documentation. 

create table 

If true, JBossCMP will attempt to create a table for the 

No, default is 

entity. When the application is deployed, JBossCMP checks 

true 

if a table already exists before creating the table. If a table is 

found, it is logged, and the table is not created. This option is 

very useful during the early stages of development when the 

table structure changes often. 

remove table 

If true, JBossCMP will attempt to drop the table for each 

No, default is 

entity and each relation table mapped relationship. When the  false 

application is undeployed, JBossCMP will attempt to drop 

the table. This option is very useful during the early stages of 

development when the table structure changes often. 

read only 

If true, the bean provider will not be allowed to change the 

No, default is 

value of any fields. This option is discussed in Chapter 3 of 

false 

the JBossCMP Documentation. 

read time out 

This is the amount of time in milliseconds that a read on a 

No, default is 

read only field is valid. This option is discussed in Chapter 3  300 

of the JBossCMP Documentation. 

row locking 

If true, JBossCMP will lock all rows loaded in a transaction.   No, default is 

Most databases implement this by using the SELECT FOR 

false 

UPDATE syntax when loading the entity, but the actual 

syntax is determined by the row locking template in the 

datasource mapping used by this entity. 

pk constraint 

If true, JBossCMP will add a primary key constraint when 

No, default is 

creating tables. 

true 

read ahead 

This controls caching of query results and cmr fields for the 

No, see Chapter 

entity. This option is discussed in Chapter 6 of the 

6 of the 

JBossCMP Documentation. 

JBossCMP 

Documentation.

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