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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



        Versions
        121314
        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

        4 comments:

        1. Anonymous1/30/2014

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

          ReplyDelete
        2. Yes Changed to 1MB rgt?

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

          ReplyDelete