Rules for Partition Formats in a Column-Partitioned Table - Analytics Database - Teradata Vantage

SQL Data Definition Language Detailed Topics

Deployment
VantageCloud
VantageCore
Edition
Enterprise
IntelliFlex
VMware
Product
Analytics Database
Teradata Vantage
Release Number
17.20
Published
June 2022
Language
English (United States)
Last Update
2023-07-11
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B035-1184
lifecycle
latest
Product Category
Teradata Vantage™
  • If you specify COLUMN format for a column partition, Vantage stores 1 or more column partition values in a physical container.

    A column partition value consists of the values of the columns contained in the column partition.

  • The following rule applies to autocompression for a column partitioning level.
    Autocompression Option or Default Column Partitioning Level Override Setting for Partition
    COLUMN AUTO COMPRESS NO AUTO COMPRESS.
    COLUMN NO AUTO COMPRESS AUTO COMPRESS.
  • If you specify COLUMN without also specifying AUTO COMPRESS or NO AUTO COMPRESS for a column partitioning level, Vantage assigns AUTO COMPRESS for the partitioning level.
  • If you specify ROW format for a column partition, Vantage stores only 1 column partition value in a physical subrow.

    A subrow is a standard Teradata row format, and the term is used to emphasize that it is part of a column partitioning.

  • If you specify a column or constraint grouping or both with COLUMN format in the column list, the grouping defines a column partition and Vantage stores 1 or more column partition values in a physical container using COLUMN format.

    If you specify a column or constraint grouping or both with ROW format in the column list, the grouping defines a column partition that stores only 1 column partition value in a physical subrow using ROW format.

    If you specify neither COLUMN nor ROW format for a column or constraint grouping, the grouping defines a column partition and Vantage determines whether to use a COLUMN or ROW format for that column partition.

  • If you do not specify an explicit COLUMN or ROW format for a partition, Vantage makes the determination for you implicitly.

    When the COLUMN or ROW format is system-determined, Vantage bases its choice of format on the size of a column partition value for the column partition and other factors such as whether a column partition value for the column partition has fixed or variable length and whether the column partition is a single-column or multicolumn partition.

    Vantage generally assigns a COLUMN format to a narrow column partition and assigns a ROW format to a wide column partition. In this context, a column partition is considered to be narrow when its size is roughly 256 or fewer bytes.

    The width of a variable length column in a column partition is estimated as



    You can submit a HELP COLUMN statement or select the ColumnPartitionFormat column from the DBC.ColumnsV(X) view to determine which format Vantage elected to use for a column partition.