Row Structure for Packed64 Systems
Base table rows are stored in packed format on packed64 format systems, so they need not align on 8‑byte boundaries. Because of this, their row structure is simpler than that of equivalent base table rows on aligned row format systems (see “Row Structure for Aligned Row Format Systems” on page 687).
Note that the Row Hash value is 4 bytes wide irrespective of the number of hash buckets the system has (see “Teradata Database Hashing Algorithm” on page 173).
Packed64 Row Structure for a Nonpartitioned Primary Index Table with Load Isolation
The following graphic illustrates the basic structure of a Teradata Database row from a table on a packed64 format system with an nonpartitioned, or traditional, primary index. The table is load isolated, so the RowLoadID field is present.
Packed64 Row Structure for a Partitioned Table
The following graphic illustrates the basic structure of a Teradata Database row from a table on a packed64 format system with a partitioned primary index:
The difference between this and the format of a nonpartitioned primary index row is the presence of a an additional 2-byte or 8‑byte partition number field, which is also a component of the RowID (partitioned table rows are an additional 4 bytes wider if they also specify multivalue compression). It is this field that generates the need for a BYTE(10) data type specification for a RowID. For nonpartitioned primary index tables, the partition number is assumed to be 0, so the rowID of an nonpartitioned primary index table is also logically BYTE(10) (see “ROWID Columns” on page 724).