>How does update on source record get reflected on JDV platform. Will that be a new record in JDV or an updated record.
If the update occurred outside the JDV it will not know about it. There is no data stored in the JDV, so there is no concept of new record, when the query issued against the source table you will see the updated record. If you are using materialized view, then a refresh is needed.
>Is it possible for JDV to run continuous queries and get all the changes as different records from an IBM DB2 database.
If there is change marker on data, then yes. But would like to know, what is intention in reading these changed records?
I join this topic.
I think the question is : "what happens is the data outside JDV changes ?
I have a datasource connected to a flat file on some folder.
The first time I initialize the datasource, it will read the content.
after the vdb has been deployed, what if the flat file is updated. It the vdb content as well updated ?
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As Ramesh indicated, JDV doesn't store or contain data. Therefore, if the data is updated, the next time a query is issue to the VDB, it will read the latest content from the file.
So, each time a query is sent to the VDB, the sources are fully read.
I did not undertand like this.
So, if I connect a datasource to DataGrid Server, each time a query will be sent to VDB, a full scan of the DG will be done ??
As to whether a full scan is done or not, depends on how you want to enable access to the data source. And this can be controlled in how you model the data source. You have options like:
- you can always provide the where clause in the query you submit
- creating a view that has configured access paths to the data source, ensuring criteria is always required when querying, so that you ensure that you are asking only for what you need
- creating views with other data sources so that join criteria will ensure the source query to the data grid is searching for a subset.
Also, to ensure DataGrid is searched properly, the cache needs to be correctly indexed.
Hope this helps.