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AdministeringIn addition to administering the database server, you can tune performance, replicate data, and archive data.
System administrationThese topics contain concepts, procedures, and reference information for database and database server administrators to use for managing and tuning HCL OneDB™ database servers.
Performance GuideThe HCL OneDB™ Performance Guide describes how to configure and operate your HCL OneDB™ database server to improve overall system throughput and to improve the performance of SQL queries.
Fragmentation guidelinesOne of the most frequent causes of poor performance in relational database systems is contention for data that resides on a single I/O device. Proper fragmentation of high-use tables can significantly reduce I/O contention. These topics discuss the performance considerations that are involved when you use table fragmentation.
Distribution schemes that eliminate fragmentsFragment elimination is a database server feature that reduces the number of fragments involved in a database operation. This capability can improve performance significantly and reduce contention for the disks on which fragments reside.
Query expressions for fragment elimination A query expression (the expression in the WHERE clause) can consist of simple expressions, not simple expressions, and multiple expressions.
Range expressions in query The database server can handle one or two column fragment elimination on queries with any combination of five relational operators in the WHERE clause.

Range expressions in query

The database server can handle one or two column fragment elimination on queries with any combination of five relational operators in the WHERE clause.

Range expressions use the following relational operators:

<
>
<=
>=
!=

The database server can also eliminate fragments when these range expressions are combined with the following operators:

AND, OR, NOT
IS NULL, IS NOT NULL
MATCH, LIKE

If the range expression contains MATCH or LIKE, the database server can also eliminate fragments if the string does not begin with a wildcard character. The following examples show query expressions that can take advantage of fragment elimination:

columna MATCH "ab*"
columna LIKE "ab%" OR columnb LIKE "ab*"