DA-LOG formatting by SEDI70

The SEDI70 program formats CAT-LOG and DA-LOG files (logging files for the catalog space and user spaces) for printing according to the input parameters of the media recovery files.

The following information is important to interpret the output:

• The CAT-LOG file contains all changes to the metadata that are applied to the catalog during a DBH session. These changes are logged as DMLs (INSERT, UPDATE, DELETE) because the metadata is stored in the catalog as a table.
  Changes to the metadata can be made

  • by a user (e.g. by CREATE TABLE, ALTER TABLE ...)

  • by the system (e.g. by entering the DA-LOG files in the SYS_INFO_SCHEMA.SYS_DA_LOGS or by changing the “time of change” time stamp in the SYS_INFO_SCHEMA.SYS_SPACES during the first update of a space within a DBH session)

• All changes to the user tables that are made during a DBH session to user spaces when the logical data backup is switched on are logged in the DA-LOG file.
  There is a system table in the user space with the table ID 1. It is used to ensure consistency between the catalog space and user space.

• CAT-LOG and DA-LOG files are divided into “units”. The units contained in a CAT-LOG or DA-LOG file can be found in the CAT-REC file or in the SYS_INFO_SCHEMA.SYS_DA_LOGS. New units are created in the following cases, for example:

  • When a file is opened (beginning of session, CAT-LOG/DA-LOG switch, COPY CATALOG)

  • In the case of logical starting points (COPY SPACE)

  • In the case of selection (LOAD)

• Changes are logged in the order in which the were made. A change is only written permanently by a COMMIT WORK. The association between the change and the corresponding COMMIT WORK is done using the 28-byte user ID. If a restart label (unit record) exists between the change and a follow-up COMMIT WORK, then the change is rolled back.
• Changes that have the same user ID and the same statement ID were produced by an external statement. For example, an update statement with 100 matches produces 100 update records in the log files. If an error occurs in the nth match (e.g. a data error), then a cancel statement takes effect. This means that all update increments with the same user ID and the same statement ID are invalid. The transaction boundary is not affected by this, i.e. it is still open and a COMMIT WORK later on commits all remaining changes of the user.

The following always applies: Output sent to SYSOUT and SYSLST is not upwardly compatible. Output layout may vary depending on the version used.