Pointer errors are related to an individual record occurrence in a specific set. CA IDMS/DB Audit can correct pointer errors in user-defined sets, integrated index sets, and CALC sets. There are six types of pointer errors.
1. Next, prior, or owner db-key points outside area page ranges in the subschema
CA IDMS/DB Audit verifies that all member records of a multi-member set to be audited, and the areas where the records reside, are copied into the subschema used by CA IDMS/DB Audit. (Except CA IDMS/DB Audit cannot verify that all CALC records are copied into the subschema when CALCSET audit is requested.) Therefore, the page number for a next, prior, or owner pointer must be for a page within an area copied into the subschema.
For example, in Figure 2.3, assume that the only area copied in the subschema is DEPT-REGION. As a result, only records within the DEPT-REGION area can be copied into the subschema. In this case, John Allen's next db-key is not within the DEPT-REGION page ranges and is in error. CA IDMS/DB Audit will fix the error by correcting the pointer so that it points to HISTORY.
Figure 2.3: Area Points to Area Outside Page Range
2. Next, prior or owner db-key points to a non-readied area
CA IDMS/DB Audit verifies whether all member records of a set to be audited, and the areas where the records reside, are copied into the subschema used by CA IDMS/DB Audit. (Except CA IDMS/DB Audit cannot verify that all CALC records are copied into the subschema when CALCSET audit is requested.) Therefore, the page number in a next, prior, or owner pointer must be for a page within an area readied by CA IDMS/DB Audit.
For example, in Figure 2.4, assume that the DEPT-REGION area was readied and the STUDENT-REGION area was not readied, because NOACCESS was specified by the user. As a result, Joan Brown's next db-key is invalid, because it points to a record that is in the non-readied area. CA IDMS/DB Audit corrects the next db-key to point to ENGLISH.
Figure 2.4: Record Points to Non-Readied Area
3. Next, prior, or owner db-key points to a non-existent record
In Figure 2.5, Carol Smith's next db-key points within the DEPT-REGION area, but the record for the specified db-key does not exist. Because the set is a user set, CA IDMS/DB Audit corrects the next pointer so that it points to the Joan Brown record.
Figure 2.5: Record Points to Non-Existent Record
4. Next, prior or owner db-key points to an invalid record type for the set
CA IDMS/DB Audit verifies whether all member records of a set are copied into the subschema used by CA IDMS/DB Audit. (Except CA IDMS/DB Audit cannot verify that all CALC records are copied into the subschema when CALCSET audit is requested.) Therefore, a valid next, prior, or owner db-key must point to a valid record type for that set.
For example, in Figure 2.6, the only valid record types for the DEPT-TEACHER set are a DEPT record and a TEACHER record. Therefore, Jane Doe's next db-key is in error because it is pointing to SUBJECT record Creative Writing. CA IDMS/DB Audit corrects the error by changing the next pointer so that it points to the MATH record.
Figure 2.6: Record Points to Invalid Record Type
5. Next, prior or owner db-key is null
The next, prior, or owner db-key for this record is equal to HIGH-VALUES. If the set is user-defined, CA IDMS/DB Audit corrects the error by entering a valid pointer.
6. Db-key of record is outside the from/thru page range for record type
This type of error probably occurs because a schema was compiled when the database was originally developed, and a FROM/THRU page range was not specified for the record type. As a result, the FROM/THRU page range defaulted to the low-area-page/high-area-page number of the area. The schema was recompiled with a different FROM/THRU page range for the record type. Some records stored before the recompilation now fall outside the new FROM/THRU page range.
This error does not affect the walking of a set, but it can cause CALC records stored before the recompilation to be lost. This loss happens because the CA-IDMS CALC routine uses the current FROM/THRU page range in its calculation of the randomized CALC page number.
In Figure 2.7, the FROM/THRU page range for the TEACHER record is pages 2500 thru 2550. The db-key of Charles Spencer falls outside this range. CA IDMS/DB Audit does not fix this type of error.
Figure 2.7: Record Points to Db-key Outside Page Range
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