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sqlfresher2k7
Aged Yak Warrior
623 Posts |
 Posted - 2007-11-26 : 22:00:49
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| There was an existing database design, which contains 4 tables.The three table contains the duplicate data.Table A contains 100 columnsTable B contains 80 columnsTable C contains 50 columnsThe data of 3 tables(1,2,3) will be de-duplicated,cleansed and loaded to Table D which contains 138 columns.My question is Table1,Table2,Table3 doesn't have a primary key defined.Table4 has a primary key.What is impact of not having a primary keys.What are the potential problem to have table4 colums of 138.Performance issues.I proposed to denormalize the database.since they don't want at this stage.I also proposed to have primary keys for the three tables..Please give me the valuable suggestions..... |
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blindman
Master Smack Fu Yak Hacker
2365 Posts |
Posted - 2007-11-27 : 08:55:33
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| 138 columns is probably excessive, and indicative of a need to normalize the schema. But if this datapile is only being used for reporting and not transaction processing, the single-table approach may be justified.Regardless, every table should have a primary key defined, either surrogate or natural. What are the natural keys on these four tables?e4 d5 xd5 Nf6 |
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jackv
Master Smack Fu Yak Hacker
2179 Posts |
Posted - 2007-12-04 : 12:17:06
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| What type of queries will you be running on this table? Is it an OLTP ?Jack Vamvas--------------------Search IT jobs from multiple sources- http://www.ITjobfeed.com |
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design issue