Cloud Computing
  • 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
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