14.8 Notes : Hitachi Advanced Database Command Reference

Do not perform read or write operations on the output data files (by using other applications) while the adbexport command is executing.

The adbexport command can export the following types of tables:

Base tables for which the EXPORT TABLE privilege has been granted
Viewed tables for which the EXPORT TABLE privilege has been granted
Dictionary tables
System tables

For details about how to improve the performance of retrieval processing by the SQL statement that is executed, see Reducing the execution time of the adbexport command in Tuning to shorten command execution time in Tuning in the HADB Setup and Operation Guide.

When the -n option is specified, the SQL statement used for retrieving table data will be SELECT * FROM "schema-name"."table-identifier".

Use X'0A' (LF) or X'0D0A' (CRLF) for the line break code in files specified in the options of the adbexport command.

Use the adbcancel command to cancel execution of the adbexport command. Alternatively, use a method such as the adbstop --force command or the OS's kill command to forcibly terminate the server process. For details about how to use the adbcancel command to suspend an executing command, see 1.6 When suspending (forcibly terminating) an executing command.

Data export processing is performed by server processes. Therefore, using the Ctrl+C keys to forcibly terminate the adbexport command process will not interrupt data export processing that is being performed by server processes (this processing continues). When the data export processing is completed, the command outputs the KFAA81001-I message to the message log file.

When multiple output data files are specified, the number of data items output for each file varies. Consequently, a file containing zero data items might be created.

The output results of a retrieval with the ORDER BY clause specified are as follows:

Exporting data to a single output data file

Data is exported to the output data file in the order specified in the ORDER BY clause.
Exporting data to two or more output data files

Data is extracted in the order specified in the ORDER BY clause, but data is grouped together and then output to the output data files. Within each file, data is sorted in the order specified in the ORDER BY clause.

If the number of retrieval results is small, all data might be output in a single data file, or an output file might be created in which no records are output.

Example:

Base table T1 contains 10 data items subject to export and values from 1 to 10 are stored in column C1. This example uses the adbexport command to export the retrieval results to three output data files in ascending order of the data in column C1.

Make sure that there is no duplication of absolute paths for the files specified in an adbexport command's options. This applies to the following files:

Export option file (specified in the -z option)
Output data path file (specified as a command option)
Output data files (specified in the output data path file)

Make sure that the names of these files differ from any file names used by any programs other than the adbexport command. If a duplicate file name is used, data in the file might be corrupted. Also make sure that symbolic links and relative paths are specified correctly.

If the adbexport command is executed while another command or application program is running, HADB might not be able to allocate the required number of processing real threads. If that happens, HADB waits until the required number of processing real threads can be allocated before executing the adbexport command. If allocation of processing real threads is placed in wait status, see the topic Points to consider about the number of processing real threads to be used during command execution in Points to consider when executing commands concurrently in Preparing Resources in the HADB Setup and Operation Guide and take appropriate action.

If none is specified for the -k option in the adbexport command, data without enclosing characters is output. For data with a length of zero bytes, nothing is output. Therefore, the data cannot be distinguished from the null value.