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Discussion on: What are some good Interview questions?

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David Aldridge • Edited

I used to recruit for Oracle practitioners, mostly for data warehousing/BI roles, and had two open ended questions that I'd regularly use.

  • What are the differences between delete and truncate?
  • What factors affect whether a query runs quickly or slowly?

Both of these could be the subject of a considerable article - in fact the latter could be an entire book - and I'd usually ask prospective applicants to write something up before an interview and send it over, and it was a very good applicant sieve.

After I stopped working primarily on databases I wrote up the truncate vs delete as a Stackoverflow Q/A.

For the query performance question, I was always hoping for something that mentioned indexing, clustering factors, table size, partitioning, query rewrite, correct use of data types, caching, hardware issues, parallel query, optimiser goals etc.. I was usually disappointed, though.