Roman Puchkovskiy created IGNITE-20133:
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             Summary: Compute hashes for integral/decimal columns in a stable 
way
                 Key: IGNITE-20133
                 URL: https://issues.apache.org/jira/browse/IGNITE-20133
             Project: Ignite
          Issue Type: Improvement
            Reporter: Roman Puchkovskiy
             Fix For: 3.0.0-beta2


The idea is to make hash computation for integral and decimal types satisfy the 
following property: if a column type is changed from an integral to a decimal 
type, the hashes for values that are already stored remain the same.

This will allow us to permit chaning type (integral -> decimal and decimal -> 
longer decimal) of a column that is included in a HASH index.

A hash that has this property is the following function: 
hash(val.toString(TRIM_TRAILING_ZEROS)). For instance, for 1 it will be 
hash("1"), for 1.000 it will also be hash("1"), but for 1.23 it will give 
hash("1.23").



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