database - Is a bitmap index the best choice for a range query?

Question

I'm trying to choose between these query plans for a range query:

• Sequential table scan
• Bitmap index
• B+ tree index
• Hash index

My instinct is that a bitmap index would work here based on what I've read. Does that sound right?

Answer 1

这个链接有一个很好的解释：http ://dylanwan.wordpress.com/2008/02/01/bitmap-index-when-to-use-it/

当然还有维基百科：http ://en.wikipedia.org/wiki/Bitmap_index

简而言之，它取决于唯一值占总行数的百分比。如果您只有几个唯一值，则位图索引可能是要走的路。