Nonstop Database, HiRDB Version 9 UAP Development Guide
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4.9.2 Application criteria
The rapid grouping facility can be used when an SQL that satisfies all the following conditions is executed:
- HiRDB/Parallel Server
- The GROUP BY clause is specified.
- Use of the rapid grouping facility is defined in the system common definitions, front-end server definitions, client environment definitions, or routine definitions.
- The selection expression column length is 4,096 or less.
- The grouping process is not for an inquiry specification that becomes the input for a set operation (UNION, EXCEPT).
- DISTINCT is not specified within the set function.
- A character string-type column with a defined length of 256 bytes or more, a BINARY-type column, or a BLOB-type column is not specified in the set function.
- When a HAVING clause is specified in the specification of a query in which the GROUP BY clause is specified, no subquery is specified in the HAVING clause.
- No subquery is specified in the selection expression.
In the following case, rapid grouping is performed regardless of whether or not the SQL optimization option is specified:
- Grouping can be executed without sorting, using a grouping column index.
The following facilities cannot be used when the rapid grouping facility is used:
- Facility for creating multiple objects
- AND multi-index use (however, this function is used with structured repetition predicates and functions dedicated to index type plug-ins).
- HiRDB/Single Server
- The GROUP BY clause is specified.
- Use of the rapid grouping facility is defined in the system common definitions, client environment definitions, or routine definitions.
- The grouping process is not for an inquiry specification that becomes the input for a set operation (UNION, EXCEPT).
- DISTINCT is not specified within the set function.
- A character string-type column with a defined length of 256 bytes or more, a BINARY-type column, or a BLOB-type column is not specified in the set function.
In the following case, rapid grouping is performed regardless of whether or not the SQL optimization option is specified:
- Grouping can be executed without sorting, using a grouping column index or by sorting join columns for sort/merge join.
The following facility is not used when the rapid grouping facility is used:
- AND multi-index use (however, this function is used with structured repetition predicates and functions dedicated to index type plug-ins).
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