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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 Informix® database servers.
Performance GuideThe Informix® Performance Guide describes how to configure and operate your HCL Informix® database server to improve overall system throughput and to improve the performance of SQL queries.
Queries and the query optimizerThese topics describe query plans, explain how the database server manages query optimization, and discuss factors that you can use to influence the query plan. These topics also describe performance considerations for SPL routines, the UDR cache, and triggers.
Time costs of a queryYou can adjust a few, but not all, of the response-time effects of actions that the database server performs when processing a query.
Index lookup costsThe database server incurs additional costs when it finds a row through an index. The index is stored on disk, and its pages must be read into memory with the data pages that contain the desired rows.
Searching for NCHAR or NVARCHAR columns in an indexA query using an index on an NCHAR or NVARCHAR scans the entire index, resulting in additional time costs.

Searching for NCHAR or NVARCHAR columns in an index

A query using an index on an NCHAR or NVARCHAR scans the entire index, resulting in additional time costs.

Global Language Support (GLS) Only

Indexes that are built on NCHAR or NVARCHAR columns are sorted using a locale-specific comparison value.

In some locales, the comparison value is not based on the code-set order. The index build uses the locale-specific comparison value to store the key values in the index. As a result, a query using an index on an NCHAR or NVARCHAR scans the entire index because the database server searches the index in code-set order.

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