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 level. The checksum setting applies to primary and fallback data rows for the hash index.

If you do not specify a value, the system assumes the system-wide default value for this table type. The result is identical to specifying DEFAULT. If you are changing the checksum for this table to the system-wide default value, then specify DEFAULT.

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.
DEFAULT
The default setting is the current DBS Control checksum setting specified for this table type.
OFF
Disables checksum disk I/O integrity checks. OFF is equivalent to NONE, which is deprecated.

Example: Hash Index With Checksum

The following hash index is created with disk I/O checksum ON:
     CREATE HASH INDEX line_hidx_6, CHECKSUM=ON 
       (l.shipdate) ON lineitem
     BY (l_shipdate)
     ORDER BY VALUES;
This creates an index that is equivalent in structure to the following join index:
     CREATE JOIN INDEX line_jidx_6, CHECKSUM=ON AS
      SELECT (l_orderkey), (l_shipdate, lineitem.ROWID) 
      FROM lineitem
      ORDER BY l_orderkey
     PRIMARY INDEX (l_shipdate);