10.11.5 Preparations for outputting SQL trace information

(1) Checking the disk capacity

The SQL trace information is output to SQL trace files. The maximum size of one SQL trace file is specified in the adb_sql_trc_txtfile_size operand in the server definition (the default is 256 megabytes). A maximum of eight SQL trace files are created. Make sure that you have sufficient disk capacity for the trace files that are created.

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(2) Specifying server definitions

You use the adb_sql_trc_out operand in the server definition to specify whether the SQL trace information is to be output. The default is Y (SQL trace information is output).

In general, we recommend that you collect all SQL trace information because the information is useful for troubleshooting and tuning purposes. However, because the SQL trace information is output to files, the performance of SQL statement processing performance might be adversely affected. As the amount of information to be output increases, the effects on processing performance might also increase. If the effects on SQL statement processing performance are too significant, you can use the following server definition operands to reduce the amount of SQL trace information that is output:

• adb_sql_trc_param

  This operand specifies whether dynamic parameter information is to be output. The default is Y (dynamic parameter information is output).

• adb_sql_trc_accesspath

  This operand specifies whether access path information and access path statistical information are to be output. The default is Y (access path information and access path statistical information are output).

• adb_sql_trc_level

  This operand specifies the unit for outputting SQL trace information. The default is SQL (SQL trace information is output for each SQL statement).

Note

After the HADB server has started, you can use the adbchgsqltrc command to stop output of SQL trace information or to change the SQL trace information that is to be output.

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