Social Icons

Teradata Facts

Below are some of the hard facts about Teradata Database and Limitations between versions.

    • Each AMP holds a portion of the rows for every table in the system.
    • Each Table has a Primary Index that is Unique or Non-Unique
    • The Hash Map Determines which AMP will own the Row
    • A Unique Primary Index Spreads the Data Evenly
    • The AMP Adds a Uniqueness Value to Create the Row-ID
    • Each AMP Sorts Their Tables by the Row-ID
    • A Non-Unique Primary Index Skews the Data
    • Unique Primary Index Queries are a Single AMP Retrieve
    • A Non-Unique Primary Index is also a Single AMP Retrieve
    • Teradata has a No Primary Index Table called a NoPI Table
    • There are Normal Tables and then There are Partitioned Tables
    • Partitioning is Designed to Eliminate the Full Table Scan
    • A Partition # and Row-ID = Row Key
    • An AMP Stores its Rows Sorted in only Two Different Ways
    • AMPs Moves Their Data Blocks into Memory to Read/Write
    • Most Taxing thing for an AMP is Moving Blocks into Memory
    • Rows are Stored in Data Blocks which are stored in Cylinders
    • Rows for an AMP Stored Inside a Data Block in a Cylinder
    • An AMP's Master Index is Used to Find the Right Cylinder
    • There is One Master Index and Thousands of Cylinder Indexes
    • The Row Reference Array is always in Row-ID order
    • The maximum block size (before a split) was 255 sectors (127.5 K), but now it is 2047 sectors (1 MB).
    • A Block Splits into Two Blocks at Maximum Block Size.
    • Once the block grows to the maximum size, then Teradata will split the single block into two separate blocks. The default for the split is 2047 sectors or 1 MB.
    • The maximum for all Teradata V14 data block splits are 2047 sectors or 1 MB, but the defaults differ based on whether or not it is an enterprise class system, or an appliance
    • Each Table has a 48-bit TableID
      Differences in Teradata vesrions V12, V13 and V14

        Max Vdisk Size1.26 TB1.26 TB7.2 TB
        Max Block Size (sectors)255255255
        Max Table Header Size128 KB1 MB1 MB
        Max Databases/Users4.2 Billion4.2 Billion4.2 Billion
        Max Partitions65,53565,5359.2 * 10 18
        Max Partition Levels151562
        Max spool tables per query204820482048
        Max Tables in a Join64128128
        Max columns in a table204820482048
        Max columns in an index646464
        Max SQL request size1 MB1 MB1 MB
        Max AMPs and PEs16,38416,38432,720


        1. Anonymous1/30/2014

          max block size(sectors) has been changed in 14 th version

        2. Yes Changed to 1MB rgt?

        3. yes naresh its 1 MB

        4. Hi Admin, Can you please post Teradata 14 Features and new concepts.