15.00 - LOB and XML Subtable Sizing Equation - Teradata Database

Teradata Database Design

prodname
Teradata Database
vrm_release
15.00
category
User Guide
featnum
B035-1094-015K

LOB and XML Subtable Sizing Equation

The following parameter definitions are used with this equation.

 

     Parameter

                                                          Definition

BaseRowCount

Estimated cardinality for the base table.

OIDSize

  • 40 bytes for nonpartitioned primary index and 2‑byte PPI tables.
  • 45 bytes for 8‑byte PPI tables.
  • RowOverhead

    The number of bytes devoted to subtable row overhead.

  • If the base table has a non-partitioned primary index, the subtable row overhead is 12 bytes.
  • If the base table has a partitioned primary index, the subtable row overhead is 16 bytes.
  • AvgLOBSize

    Average LOB or XML string size for the table.

    Remember that all row lengths must be an even number of bytes (see “Byte Alignment” on page 770), so be sure to take this into account.