15.10 - CHECKSUM - Teradata Database

Teradata Database SQL Data Definition Language Syntax and Examples

prodname
Teradata Database
vrm_release
15.10
created_date
December 2015
category
Programming Reference
featnum
B035-1144-151K

A table-specific disk I/O integrity checksum for detection of hardware read errors. The checksum level setting applies to primary data rows, fallback data rows, and all secondary index rows for the table.

For a system-defined join index, the integrity checking setting you specify for a base table also applies to any system-defined join indexes defined on that table. You cannot specify integrity checking for a system-defined join index directly.

The HIGH, MEDIUM, LOW settings are deprecated and are equivalent to specifying ON.
ON
Calculate checksums using the entire disk block. Sample 100% of the disk blocks to generate a checksum. ON is equivalent to ALL, which is deprecated.
OFF
Disables checksum disk I/O integrity checks. OFF is equivalent to NONE, which is deprecated.
DEFAULT
The default setting is the current DBS Control checksum setting specified for this table type.
IMMEDIATE
The checksum setting is updated immediately for this table, including all data blocks and cylinder indexes. If you do not specify this option, the checksum setting is updated the next time the data blocks and cylinder indexes are updated and written to disk.

Example: Changing CHECKSUM to the Default

The following ALTER TABLE request changes the disk I/O integrity checksum value to the system default:
     ALTER TABLE employee,CHECKSUM = DEFAULT;