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Procedure documentation Checking Table Activity (Informix)  Locate the document in its SAP Library structure

Use

You can use the detailed database analysis in the SAP/Informix database monitor to check table activity.

Prerequisites

You need Informix version 7.x to use the full functionality described in this procedure.

Procedure

  1. Choose Tools ® CCMS ® Control/Monitoring ® Performance Menu ® Database ® Activity ® Detail Analysis Menu ® Table Activity.

The system displays the numbers of reads and writes for each table in the database. For each table, look at the fields Bufreads and Bufwrites to see information on access through the buffer (that is, from copies of the data held in main storage). You can see information on disk accesses under the fields Pagereads and Pagewrites.

You can change the information you see in the display as follows:
  1. To view information about the number of times a table has been accessed by a sequential scan and the number of rows in each table, choose Next info.

    2. The system displays different fields, including Seqscans and rows.

  2. To view information about ISAM reads and writes, choose Next info again.

    3. The system displays different fields, including Isreads, Iswrites, Isrewrites and Isdeletes.

  3. To view information about locking, choose Next info again.

    4. The system displays different fields, including Users, Lockreqs Deadlocks, Lktouts, Lockwts.

    Note

    You can change the display to alternately show the fields described in steps 1 (what you see when you start), 2, 3, and 4 by choosing Next info and Prev info.

  4. To view statistics information for a single table, select the table you want to examine and choose Last Statistic.

    5. The system displays the date the table’s statistics were last updated and the level of the update.

  5. To view statistics information for all tables, choose Edit ® Update Statistics ® Display all tables.

    6. For all tables, the system displays the date the table’s statistics were last updated and the level of the update.

  6. To always see statistics information for all tables, choose Edit ® Update Statistics ® Display permanently ® On.

    7. For all tables, the system always displays the date the table’s statistics were last updated and the level of the update.

  7. To refresh the statistics information for all tables, choose Edit ® Update Statistics ® Read/Display all new.

    8. The system displays the updated statistics information for all tables.

  8. You can view different starting points for the information (the system displays Informix Table Activity Monitor since DB start at first):
    9.

    Choose

    To

    Reset

    Set all figures to zero

    Since Reset

    Display table activity since the last time Reset was chosen

    Since DB Start

    Display table activity since your Informix database management system (DBMS) was started

    When you choose Reset or Since Reset, the system alters the title of the display accordingly, for example:

    Informix Table Activity Monitor since 11:36:18

  9. To sort the data by a field, place the cursor on a data element in a column heading and choose Sort. This is useful, for example, to see which tables have the most activity.

If you are viewing information on the number of sequential scans (see step 2), you can sort the information on this field, enabling you to see the tables with the most sequential scans. Look at the field rows to see whether the sequential scan makes sense (for tables with less than approximately 100 rows, it is normally better to do a sequential scan than to use an index).

 

See also:

Data Buffers (Informix)

BUFFERS (Informix)