DV: QlikView Developer | Jim: Database Administrator
DV: Hi Jim, can I get full access to Sales table on ORCAPROD?
Jim: Why do you need full access?
DV: I need it to extract the data to build a QlikView application for Finance and Operations.
Jim: In that case, don’t you just need read access to the database or relevant tables?
DV: ah ok, what is the difference between read access and full access?
Jim: With full access you will have permissions to read, write and possibly provide access to other users. However, with read access you will just have read-only permissions to the table. In your case, you don’t need write permissions as you will be extracting the data from the database/tables.
DV thought – “I’ll remember this now, never ask for full access when I have to extract the data from the DB”.
DV: Thank you Jim, can you provide me read-only access to the table(s)?
Jim: Sure, but don’t need access to Service Account instead of your personal account or may be you need both?
DV: I’m not sure, what is Service Account?
Jim: A service account is a user account that is created explicitly to provide a security context for services running on Windows. Think of service account as a special user account that an application or service uses to interact with the operating system. Services use the service accounts to log on and make changes to the operating system or changes to the underlying files, in your case it will be QVW and QVD files. Through permissions, you can control the actions that the service can perform.
DV: That’s helpful to know, now I understand what is service account and why it is used. Thank you!
Jim: I’m glad you understand that now. BTW – are you aware that this table hold over 10 million rows? So, please make sure that you use “Where” clause whilst testing or extracting the data from the table. Also, we have a non-clustered index on “BusinessDate”, so try to use it.
DV: hmm! sorry, I’m not sure what is a non-clustered Index and what is it do with the “BusinessDate” field?
Jim: NP, With a clustered index the rows are stored physically on the disk in the same order as the index. There can therefore be only one clustered index. With a non clustered index there is a second list that has pointers to the physical rows. You can have many non clustered indexes, although each new index will increase the time it takes to write new records. So, when you use “BusinessDate” as part of “where” clause it will in-turn use the non-clustered index.
DV: That is very helpful. Thank you very much Jim!