- Specified system data structures
- Data subtables
- Large object (LOB) subtables
- Unique and nonunique secondary indexes (USIs and NUSIs), including geospatial indexes
- System-defined join indexes (SJIs)
The following table summarizes the specific level-one checks. These checks are in addition to the general checks performed for all check levels. For more information on these general checks, see CheckTable General Checks.
Object Checked | What CheckTable Does |
---|---|
table dictionary or table header |
To correct the table header or the partitioning of rows, use the ALTER TABLE statement with the REVALIDATE PRIMARY INDEX option. For more information on ALTER TABLE, see Teradata Vantage™ - SQL Data Definition Language Syntax and Examples, B035-1144. |
reference index |
|
data subtable |
This check is performed only for tables that have fallback. This check requires access to all AMPs in a cluster. If any AMP in a cluster is down or unavailable, no AMPs in that cluster are checked.
|
LOB subtable |
In the case of LOB subtables, there is not a one-to-one correspondence in the row counts of the base data table and the LOB subtable, since LOBs may span multiple physical rows in the LOB subtable. For example if a base data table row points to a LOB that is 198,000 bytes in length, there will be four rows in the LOB subtable for this object (three rows containing 64,000 bytes and one row containing 6,000 bytes). When the counts are compared against the base data table, these four rows are counted by CheckTable as a single row. |
USI | checks if any AMP has any USIs flagged as invalid. CheckTable compares the following:
For USIs and NUSIs, an invalid index is not an error. Unless the index is excluded explicitly from the check, CheckTable issues a warning. This check requires access to all AMPs in a cluster. If any AMP in a cluster is down or unavailable, no AMPs in that cluster are checked.
|
NUSI |
Because the NUSI rows reside on the same AMP as the data rows, this check can be run without having all AMPs online. However, relationships between data and index subtables on unavailable AMPs are not checked. For USIs and NUSIs, an invalid index is not an error. Unless the index is excluded explicitly from the check, CheckTable issues a warning. |
SJI |
SJIs are generated by Teradata Database for temporal tables that have temporal unique constraints. For more information on temporal tables and constraints, see Teradata Vantage™ - Temporal Table Support , B035-1182 . |