CAT-LOG files

CAT-LOG files are log files for the catalog space (see section “Logging”).

Contents of the CAT-LOG file

In CAT-LOG files, SESAM/SQL logs all the changes in the catalog space. Changes in the catalog space are caused by SQL statements used to administer the storage structure, by utility statements, by SQL statements used to administer user entries, and by SQL statements for the definition and administration of schemas. In particular, SESAM/SQL logs all changes to the RECOVERY_UNITS and DA_LOGS catalog tables in CAT-LOG files.Moreover, SESAM/SQL documents each copy made of the database and each copy made of the catalog space in the CAT-LOG file. The creation of a copy of the database or the catalog space automatically triggers a change of CAT-LOG file. The SESAM backup copies serve as resumption points when applying logged modifications during the repair of the database or the catalog space (see section “Recovering the database, catalog space and user spaces”).

Storage medium, primary and secondary assignments

SESAM/SQL creates the first CAT-LOG file during the execution of the utility statement CREATE CATALOG. The file is created on the storage medium (disk) and the primary assignment is made in accordance with the information contained in the first CAT-LOG media record in the media table (the secondary assignment is always 0). SESAM/SQL creates subsequent CAT-LOG files in accordance with the information given in the media table.

The following default values apply for primary and secondary assignment of the CAT-LOG files: 768 (primary assignment) and 0 (secondary assignment).

BS2000 file name

CAT-LOG files have the following file name in BS2000:
   user_id.catalog.version.C.nnnn

user_id catalog version nnnn

BS2000 user ID Name of the database six-digit version number of a SESAM backup copy of the catalog space serial number of the CAT-LOG file, which indicates that it is the nnnnth created since the SESAM backup copy with the number version for the catalog space. Gaps may occur in the consecutive numbering.

Opening the CAT-LOG file

If, when opening the CAT-LOG file at open time, the storage media defined via CREATE CATALOG or ALTER MEDIA DESCRIPTION for the CAT-LOG file are full or cannot be accessed, then CC occurs. After this CC, only read access to the database is possible. The CC changes the entry in the SQL database catalog from ACCESS=WRITE to ACCESS=READ.

To ensure that the file can be opened correctly, the user must create memory space on the relevant medium or make the medium accessible. If this not possible, issue a CREATE FILE command with the name of the CAT-LOG file (name from the error message in the SYSLST file). The user must use the SESADM administration program to reset the entry in the SQL database catalog to ACCESS=WRITE.

Switchover to a different CAT-LOG file

SESAM/SQL switches to a different CAT-LOG file in the following situations:

• When a new SESAM backup copy of the whole database or the catalog space is created. In this case, the new CAT-LOG file is given the version number of the new SESAM backup copy of the catalog space and the serial number 0001, e.g. catalog.000017.C.0001.

• The serial number of the DA-LOG file overflows.
  In this case the new CAT-LOG file is given the version number incremented by one and the serial number 0001, e.g. catalog.000018.C.0001.

• The space in the CAT-LOG file is exhausted.

• An error occurs in the BS2000 DMS.

In the latter two cases, the new CAT-LOG file retains the same version number as its predecessor and the serial number is incremented, e.g. catalog.000017.C.0002.

In addition, the CHANGE-CATLOG administration statement can be used to switch the CAT-LOG file and the DA-LOG files to the relevant database(s) (see the “Database Operation” manual). In this case, the version number also remains unchanged and the serial number is incremented.