Answered Questions

  • Storing Character String

    In a compiler there is 36 bit for a word and to store a character 8bits are needed. IN this to store a character two words are appended. Then for storing a K characters string, How many words are neededA. 2k/9B. (2k+8)/9C. (k+8)/9D. 2*(k+8)/9E. none

  • Java SUPER

    Is SUPER a keyword or method? Explain Why?

  • How do we maintain Primary key in Fact Table ?

    Is there any option other than Surrogate key or concatenated key?

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    • Member Since May-2008 | May 9th, 2009

    Two main reasons to generate and maintain a surrogate key on DW side:

    1. If your DW has multiple sources for a dimension or fact, the PK ID fields can have same values from different sources. The only way you can handle this is by maintaining the composite primary key on these columns. Now lets imagine that you have some 10 dimensions in a subject area, you would expect to have only 10 keys in the Fact, but by having the composite keys you would endup creating 20 or more keys on the fact. This would inturn adversely affect your query performance.

    2. Another case, suppose some data migration activities take place on the source side -- which is quite possible if the source system platform is changed or your company acquiered another company and integrating the data etc -- if the source side architect decides to change the PK field value itself of a table in source, then your DW would see this as a new record and insert it and this would result in data inconsistency /discrepency between the source and DW and it could be a nightmare to fix the issue. By having a separate surrogate key on DW side that is generated based on the grain of the source table (not on the IDs), you are immune to any such PK value changes on the source side.

  • why is multiple inheritance not allowed in java?


    • Oct 12th, 2017

    Java does not supports multiple inheritance at all, but it supports similar feature interface. Which removes the ambiguity problem (Deadly Diamonds Of Death) and complexity of multiple inheritance....


    • Sep 7th, 2017

    Because sub class goes into the state of ambiguity if diffrent super classes implement same method name or same variable name.