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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.
Indexes and index performance considerationsInformix® provides several types of indexes. Some performance issues are associated with indexes.
Managing indexesAn index on the appropriate column can save thousands, tens of thousands, or in extreme cases, even millions of disk operations during a query. However, indexes entail costs.
Indexes on columnsYou can create an index for one or more columns in a table. Indexes are required on columns that must be unique and are not specified as primary keys.
ClusteringClustering is a method for arranging the rows of a table so that their physical order on disk closely corresponds to the sequence of entries in the index.
Configuration parameters that affect the degree of clusteringThe clust field in the sysindexes or the sysindices table represents the degree of clustering of the index. The values of several configuration parameters affect the clust field.

Configuration parameters that affect the degree of clustering

The clust field in the sysindexes or the sysindices table represents the degree of clustering of the index. The values of several configuration parameters affect the clust field.

The value of this field is affected by:

The size of the buffer pool as specified by the BUFFERPOOL configuration parameter
The DS_MAX_QUERIES configuration parameter, which specifies the maximum number of PDQ queries that can run concurrently

Each of these configuration parameters affects the amount of buffer space available for a single user session. Additional buffers can result in better clustering (a smaller clust value in the sysindexes or sysindices tables).

You can create more buffers by performing one or both of the following tasks:

Increasing the size of the buffer pool by updating the value of the BUFFERPOOL configuration parameter
Decreasing the value of the DS_MAX_QUERIES configuration parameter

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