Teradata Parsing Engine Details

parsing engine
You may think that Teradata is super faster in handling data requests. The background is Parsing engine. It handles efficiently. I have given complete functions to your read now. 

 Basic functionalities of Teradata Parsing Engine
    • It handles session control
    • Logon/Logoff
    • Managing Session
    • BYNET
    • AMP
      Other functions
      • Acts like parser
      • Parse and Optimize SQL requests
      • Dispatching optimized plan to AMPs over BYNET
      • Send Query result back to requesting client
      • Responsible for Hashing data
      Flow diagram:

      Session control --> Parser --> Optimizer--> Dispatcher
      • Locally couples SMP Nodes in multi node system
      • Carries message between AMPs and PEs
      • Communication between nodes -point to point broadcast
      • Merges answer sets back to PE
      Performs DB and file management operations:
      • - Finding requested rows
      • - LOCKS
      • - Sorting
      • - Joins
      • - Output data conversion
      • -Accounting/Journaling

      Comments

      Post a Comment

      Popular posts from this blog

      SQL for Quantile Function in Teradata

      Image
      A Quantile is used to divide rows into a number of categories or grouping of roughly the same number of rows in each group. Quantile Function The percentile is the QUANTILE most commonly used in business. This means that the request is based on a value of 100 for the number of partitions SELECT Product_ID1, Sales_Date1, Daily_Sales1 ,QUANTILE(100, Daily_Sales1 ) AS "Quantile1" FROM Sales_Table WHERE Product_ID1 < 3000 AND Sales_Date1 > 1000930 ; The calculation is percentile for every row in the Sales table on Daily sales.
      Read more

      3 Uses of SAMPLE function in Teradata

      Image
      Usage-1 It returns a rows randomly from Teradata database. Syntax for SAMPLE function: SAMPLE [WITH REPLACEMENT]    [RANDOMIZED ALLOCATION]                  [WHEN <condition>  THEN]                  {<number-of-rows> | <percentage>}    […,<number-of-rows> | <percentage>]                  [ELSE {<number-of-rows> |    <percentage }   END] Usage 2 It allows the user to get absolute number of rows or percentage of rows. Usage 3 It also allows the rows to get from multiple samples How to get random rows from a table: SELECT * from sample_table SAMPLE 5; How to get certain percentage of rows: SELECT * from sample_table SAMPLE .30; How to get multiple SAMPLE data from a single tables with out duplicates: SELECT * from sample_table SAMPLE .20, SAMPLE .30 ORDER BY 1,2; SQL query to get 3 samples with duplicates: So 'WITH REPLACEMENT" you will get duplicate rows: SELECT ST_
      Read more

      All You Need NULL Value Functions

      Image
      The below are the Null value functions in Tearadata. One is "NVL" and another one is "NVL2". These two functions are part of Teradata SQL . NVL -The NVL function replace null value with a string or numeric value. This is the functionality is same as Teradata function NULLIF. It requires two arguments. If the value is not null, it will not do anything. The best SQL Null functions  NVL function:  SELECT NVL (NULL,'USA'), NVL('SPAIN','USA'); ----------- USA SPAIN Also Read: Top 70 Teradata Interview Questions The NVL2 function : Returns one of two specified values (arguments#2 and Arguments#3) based on weather the first arguments in NULL or not. It requires three arguments. The rule is as follows: If expression 1 is not null, expression 2 is returned If expression 1 is null, expression 3 is returned The best NVL2 example SELECT NVL2(NULL,'FRANCE','SPAIN'), NVL2('ENGLAND','FRANCE','SPAIN'
      Read more