In many cases, it is worthless to have an index on a 2-values field. Say you have 1,000,000 rows and that 40% are 0 and 60% are 1 what will be the added value of this index? More time will be lost going from the index pages to real data pages then a table scan will take.



>>Because this flag is only has two value (0,1). I read some articles. They said in this case. Index is not very useful.
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>>Thanks
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>If this is written, then it is better not to read these articles.