Data warehousing /Business intelligence

Question

Does anyone have a list of data warehousing /Business intelligence interview questions?
or can share the Data warehousing/BI interview experience with me?

Answer 1

I've included links to them.
Don?t over index your OLTP tables, as every index you add increases the time it takes to perform INSERTS, UPDATES, and DELETES. There is a fine line between having the ideal number
of indexes (for SELECTs) and the ideal number for data modifications
Too many indexes on frequently updated (inclusive of inserts, updates and deletes) tables incur extra index maintenance
overhead. Generally, OLTP database designs should keep the number of indexes to a
functional minimum, again due to the high volumes of similar transactions combined with the cost of index maintenance.
Unused indexes incur the cost of index maintenance for inserts, updates, and deletes without benefiting any users. Unused
indexes should be eliminated. Any index that has been used (by select, update or delete operations) will appear in sys.dm_db_index_usage_stats. Thus, any defined index not included in this DMV has not been used since the last re-start of SQL Server.
I generally start to get concerned when I see more than about five or six relational indexes on a volatile table. Having too many relational indexes
has a negative effect on insert, update, and delete performance. Ultimately, it is a judgment call, based on your workload, your hardware and I/O subsystem, and on your experience.
Standard practices call for indexing strategies in OLTP systems to target an increase in concurrency versus query support; however, more indexes have to be created than is
desired to reach acceptable query performance. The lower the proportion of write operations is in the system, the higher the level of indexing that can be tolerated, unless the timing of specific write operations is critical ref.http://www.bidn.com/blogs/TomLannen/bidn-blog/2625/indexing-strategies-for-oltp-databases
Ahsan Kabir Please remember to click Mark as Answer and Vote as Helpful on posts that help you. This can be beneficial to other community members reading the thread. http://www.aktechforum.blogspot.com/