Category Archive: TD Basics

May 21

Teradata No Primary Index Tables

What are No Primary Index tables ? Starting with Teradata Release 13, tables can be defined without having a primary index. As we all know, the primary index is the main idea behind an evenly data distribution on a Teradata system. By design, the primary index ensures that a Teradata system is unconditionally scalable. Hence, …

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Mar 21

Partition Primary Index – Advantage and Disadvantage

Advantage of Partition Primary Index – Partitioned Primary Index is one of the unique features of Teradata, which is used for distribution of rows based on different partitions so that they can be retrieved much faster than any other conventional approach. Maximum partitions allowed by Teradata – 65,535 It also reduces the overhead of scanning the complete …

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Feb 25

Partition Primary Index – Basics

Partitioned primary index or PPI is used for physically splitting the table into a series of subtables. With the proper use of Partition primary Index we can save queries from time consuming full table scan. Instead of scanning full table, only one particular partition is accessed. Follow the example below to get the insight of PPI – …

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Jan 17

Compression in Teradata

What is Compression in Teradata Compression is the feature of Teradata which helps to reduce the disk storage. It is useful in reducing the disk space required by FIXED LENGTH columns or NULLS. It is a loss less compression so no data will be lost in it. We can do compression on the following data …

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May 16

Secondary Index in Teradata

Before you start with SI, well I must say that as a prerequisite you must first read about the Primary index in Teradata. So after knowing about Primary index the point here is that when we already have UPI and NUPI then what’s the use of this Secondary Index? Well the best possible answer for …

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Feb 21

Collect Statistics in Teradata

Statistics are data demographics (or hints) used by the Teradata optimizer. There are many ways to generate a query plan for a given SQL, and collecting statistics ensures that the optimizer will have the most accurate information to create the best access and join plans. The optimizing phase of Teradata, makes decisions on how to …

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Dec 25

Join Indexes

The join index JOIN the two tables together and keeps the result set in the permanent space of Teradata. This JOIN index will hold the result set of the two table, and at the time of JOIN parsing engine will decide whether it is fast to build the result set from the actual BASE tables …

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