Multivalue compression and the indication of nullability are different matters, but with one common task: The storage of information about column values in every single row. To keep space requirements low, Teradata stores information about nullability and multivalue compress together in the so-called presence bytes. The alert reader might recognize that the name "presence byte" suggests that it's indicating the presence of NULL values. In earlier...
teradata group by
  If you work in a well-organized environment where diligence and discipline prevail and great effort is put into designing things right, in the beginning, the following post might seem outlandish to you. Else, read on. In a more “experimental” table design landscape, you will soon come across inconsistencies between column names, Teradata data types and their length decimal or format...

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teradata access paths

The Teradata Access Paths

Data access on Teradata can be classified by the number of involved AMPs, and the method Teradata is using to search the rows inside...
teradata temporal

Teradata Temporal Query Processing Review

It is assumed that you are familiar with the basic concepts of historization to get the most out of this article. Temporal data management is...

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What are Deadlocks? Deadlocks occur when each of two transactions holds the lock on a database object the other transaction needs next. Here is an example: Transaction 1 locks some rows in table 1, and transaction 2 locks some rows in table 2. The next step of transaction 1 is to lock rows in table 2  and...
teradata sliding window merge join
One of a kind: DWH Pro gives you a detailed description about the Teradata sliding window merge join. There is almost no information available about how this join process works. Therefore we decided to immerse ourselves deeply in this topic and present you our insights. Before explaining the details of the...
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Did you know that the columns selected in an SQL select statement can impact query performance? The following example will prove above statement.  The example query is doing an INNER JOIN between two tables: CREATE SET TABLE TheDatabase.TheTable1 ( REF_PK BIGINT NOT NULL, COL1 CHAR(20) NOT NULL, COL2 INTEGER, ... COL99 CHAR(100) ) PRIMARY INDEX ( COl1 );   CREATE MULTISET TABLE...

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Teradata Partitioning – Row vs. Column

Teradata Partitioning - Row vs. Column Column and row partitioning are two different methods of partitioning tables, with the goal to minimize data access resource usage. Row...

Teradata Stored Procedures – Error Handling

Overview Error handling in Teradata Stored Procedures is condition based, having the same functionality offered by modern programming languages (C++, Java, etc.). Without the availability of...
teradata join index

The Teradata Join Index Guide – We leave no Questions...

 What is the Teradata Join Index (JI)? Join indexes store pre-joined tables, the result of aggregations, or merely change a table to a different physical structure. No matter...
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