Informix SQL Workload Test

To minimize the workload on the physical disk, the Informix Dynamic server is provided with a buffer. In the buffer, the server stores the recently accessed data, as well as query plans for recently submitted queries and invoked stored procedures. This makes it possible to retrieve the result of a query without accessing the physical disk for frequently accessed tables. Too few queries in the buffer means more direct disk accesses! To minimize reads to physical disks, more number of queries should execute from the buffer. This in turn minimizes load on the physical disk and reduces the time taken for query execution. Using this test, you can determine the number of reads that are currently performed in the buffer and the physical disk and also figure out the average and maximum time taken for query execution. In the process, the test also measures the time that the SQL statement had to wait for I/O, the maximum time the system waited for locks during SQL statement executions, etc.

Target of the test : A Informix Dynamic Server

Agent deploying the test : An internal agent

Outputs of the test : One set of results for the Informix server being monitored.

Configurable parameters for the test
Parameters Description

Test Period

This indicates how often should the test be executed.

Host

The IP address of the Informix Dynamic server.

Port

The port number at which the specified host listens to.

Instance

The Informix server instance being monitored.

User

A valid Informix user name.

Password

The password corresponding to the above user.

Confirm Password

Confirm the Password by retyping it here.

DBLocale

Specify the language/locale in which your database is installed. This will allow you to return the query in the language supported by your database. By default this attribute is set to “none”, which means that by default, queries are returned in the English locale.

ClientLocale

Specify the language/locale in which the eG agent is running. Normally, when you use an internal agent to monitor Informix, the ClientLocale and DBLocale will be same. However, the ClientLocale may differ when you are monitoring the Informix tests using a remote agent (agentless monitoring). By default, the ClientLocale is set to “none”, indicating that the eG agent runs in the English locale, by default.

Detailed Diagnosis

To make diagnosis more efficient and accurate, the eG Enterprise suite embeds an optional detailed diagnostic capability. With this capability, the eG agents can be configured to run detailed, more elaborate tests as and when specific problems are detected. To enable the detailed diagnosis capability of this test for a particular server, choose the On option. To disable the capability, click on the Off option.

The option to selectively enable/disable the detailed diagnosis capability will be available only if the following conditions are fulfilled:

  • The eG manager license should allow the detailed diagnosis capability
  • Both the normal and abnormal frequencies configured for the detailed diagnosis measures should not be 0.
Measurements made by the test
Measurement Description Measurement Unit Interpretation

Avg physical reads

Indicates the rate at which the reads performed by the queries that executed directly on the physical disk.

Reads/execution

A high value indicates that one/more queries are reading too frequently from the physical disk. This is an unhealthy practice and can be attributed poor cache usage.

Use the detailed diagnosis of this measure to know which queries are not executing in the cache and the number of times each of these queries read directly from the physical disk. This way, you can quickly identify that query which exerts the maximum pressure on the physical disk.

Max physical reads

Indicates the maximum number of reads performed by the queries that executed directly on the physical disk.

Reads/execution

 

Avg buffer reads

Indicates the average number of reads performed by the queries that executed from buffers.

Reads/execution

 

Max buffer reads

Indicates the average number of reads performed by the queries that executed from buffers.

Reads/execution

 

Avg elapsed time

Indicates the average time taken for the query execution.

Seconds

 

Max elapsed time

Indicates the maximum time taken for the query execution.

Seconds

 

Avg lock wait time

Indicates the average time the system waited for locks during SQL statement executions.

Seconds

Ideally, this value should be very low. A high value or a consistent increase in the value may choke the database server and severely hamper its overall performance. Therefore, if the value of this measure is high, you might first need to identify what is causing the lock waits. use the detailed diagnosis of this measure to more details on the lock waits.

Max lock wait time

Indicates the maximum time the system waited for locks during SQL statement executions.

Seconds

 

Avg I/O wait time

Indicates the average amount of time that the SQL statement had to wait for I/O.

Seconds

Using the detailed diagnosis of this measure reveals the information like name of the user, the number of reads performed on the physical disk and the buffer, the time the system waited for locks, the count of locks, etc.

Max I/O wait time

Indicates the maximum amount of time that the SQL statement had to wait for I/O.

Seconds