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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.
Improving individual query performanceYou can test, monitor, and improve queries.
Optimize user-response time for queriesYou can influence the amount of time that Informix® takes to optimize a query and to return rows to a user.
Optimization goalsOptimizing total query time and optimizing user-response time are two optimization goals for improving query performance.
Preferred query plans for user-response-time optimizationWhen the optimizer chooses query plans to optimize user-response time, it computes the cost for retrieving the first row in the query for each plan and chooses the plan with the lowest cost. In some cases, the query plan with the lowest cost for retrieving the first row might not be the optimal path to retrieve all rows in the query.
Table scans versus index scansIn cases where the database server returns a large number of rows from a table, the lower-cost option for the total-query-time goal might be to scan the table instead of using an index. However, to retrieve the first row, the lower-cost option for the user-response-time goal might be to use the index to access the table.

Table scans versus index scans

In cases where the database server returns a large number of rows from a table, the lower-cost option for the total-query-time goal might be to scan the table instead of using an index. However, to retrieve the first row, the lower-cost option for the user-response-time goal might be to use the index to access the table.

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