Use RLE for low-cardinality columns, where the average repetition count is less than 10???

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beth
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Use RLE for low-cardinality columns, where the average repetition count is less than 10???

Post by beth » Sun May 24, 2015 11:55 am

Hi all,

I was reading the 7.1 docs and came across this paragraph:
The advantage of RLE is that it reduces disk I/O and results in a smaller storage footprint for the database. Use RLE for low-cardinality columns, where the average repetition count is less than 10. For example, a gender column with 47 F values and 56 M values can benefit from RLE. A gender column with 6 F values and 10 M values, where the average repetition count is 8, does not benefit from RLE.
It doesn't make sens to me that it says "Use RLE for low-cardinality columns, where the average repetition count is less than 10" and then says "A gender column with 6 F values and 10 M values, where the average repetition count is 8, does not benefit from RLE."

Isn't 8 < 10 ??? So shouldn't it benefit from RLE?

BTW, here is a link to the confusing text:

https://my.vertica.com/docs/7.1.x/HTML/ ... nce|_____2

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