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https://issues.apache.org/jira/browse/IGNITE-19935?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Pavel Tupitsyn updated IGNITE-19935:
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Description:
A hash of two columns currently is
{code}
var coloHash = hash(col1, hash(col2, 0));
{code}
which means we need to access the *value of col1* after we compute the *hash of
col2*. In other words, there is no way to calculate individual column hashes
and combine them later.
In practice this means we can't combine serialization and hashing when
colocation column order is different from serialization order. As a result, we
have to do the same work twice:
1. Extract colocation column values (from tuple or POJO)
But should be
var coloHash = hashCombine(hash(col2), hash(col1))
> Allow combining individual colocation hashes
> --------------------------------------------
>
> Key: IGNITE-19935
> URL: https://issues.apache.org/jira/browse/IGNITE-19935
> Project: Ignite
> Issue Type: Improvement
> Affects Versions: 3.0.0-beta1
> Reporter: Pavel Tupitsyn
> Assignee: Pavel Tupitsyn
> Priority: Major
> Labels: ignite-3
> Fix For: 3.0.0-beta2
>
>
> A hash of two columns currently is
> {code}
> var coloHash = hash(col1, hash(col2, 0));
> {code}
> which means we need to access the *value of col1* after we compute the *hash
> of col2*. In other words, there is no way to calculate individual column
> hashes and combine them later.
> In practice this means we can't combine serialization and hashing when
> colocation column order is different from serialization order. As a result,
> we have to do the same work twice:
> 1. Extract colocation column values (from tuple or POJO)
> But should be
> var coloHash = hashCombine(hash(col2), hash(col1))
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