is an expression of any data type. For the purpose of hash segmentation, each expression is a column reference.
Syntax
[ tablename. ] columnname
Semantics
tablename
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is one of:
- the name of a table
- an alias for a table defined by means of a FROM clause in a query
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columnname
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is the name of a column that must be unique across all the tables being used in a query
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Notes
- There are no space characters in a column reference.
Hash segmentation allows you to segment a projection based on a built-in hash function that provides even distribution of data across some or all of the nodes in a cluster, resulting in optimal query execution.
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