Task 4: Load Initial Data

Load the cache group.

1. Reconnect as the TimesTen cache administration user. Use the ttIsql cachegroups command to view the definition of the customer_orders cache group:

   % ttIsql "DSN=cache1;UID=cacheadmin;PwdWallet=/wallets/cacheadminwallet"
   Command> cachegroups;
   
   Cache Group CACHEADMIN.CUSTOMER_ORDERS:
   
     Cache Group Type: Read Only
     Autorefresh: Yes
     Autorefresh Mode: Incremental
     Autorefresh State: Paused
     Autorefresh Interval: 5 Minutes
     Autorefresh Status: ok
     Aging: No aging defined
   
     Root Table: SALES.CUSTOMERS
     Table Type: Read Only
   
     Child Table: SALES.ORDERS
     Table Type: Read Only
   
   1 cache group found.

   See ttIsql in the Oracle TimesTen In-Memory Database Reference.

   Note that, in the output above, the state of autorefresh operations are currently Paused for all of the cache groups that you just created.

   Autorefresh State: Paused 

   By default, all read-only cache groups defined with incremental autorefresh start as paused (note that the default interval value is 5 minutes).

2. Load the cache group with a LOAD CACHE GROUP statement for the first load of the read-only cache group. The LOAD CACHE GROUP populates the cache tables (initially, the cache tables are empty) and changes the autorefresh state from PAUSED to ON.

   
   
   
   Description of the illustration roquicks6.eps
   
   

   The following example performs a LOAD CACHE GROUP statement for the first load of the customer_orders read-only cache group since the cache tables are empty. In this case, the example specifies 3 parallel threads to make the load more efficient and a commit is issued every 256 rows during the load operation.

   LOAD CACHE GROUP customer_orders COMMIT EVERY 256 ROWS PARALLEL 3;
   2 cache instances affected.

   See LOAD CACHE GROUP in the Oracle TimesTen In-Memory Database SQL Reference.

3. Use the ttIsql cachegroups command again to show that the state for autorefresh state is now On for the customer_orders cache group:

   Command> cachegroups;
   
   Cache Group CACHEADMIN.CUSTOMER_ORDERS:
   
     Cache Group Type: Read Only
     Autorefresh: Yes
     Autorefresh Mode: Incremental
     Autorefresh State: On
     Autorefresh Interval: 5 Minutes
     Autorefresh Status: ok
     Aging: No aging defined
   
     Root Table: SALES.CUSTOMERS
     Table Type: Read Only
   
     Child Table: SALES.ORDERS
     Table Type: Read Only
   
   1 cache group found.

4. Query the contents of sales.customers cache table.

   Command> SELECT * FROM sales.customers;
   122, West, Jim Johnston
   663, MidWest, Pat Reed
   2 rows found.

Since this is a static read-only cache group with autorefresh, all changes on the Oracle database are automatically refreshed into the cache group at the default interval. Since these are read-only cache tables in TimesTen, any DML statements run against them will fail.