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Data Modeling Considerations In relational data modeling theory, each entity needs a primary key. Each primary key value uniquely identifies an object. Early releases of Teradata followed the rules of relational data modeling tightly and did not allow row duplicates in a table, and Teradata Multiset Tables were not available. As a logical data modeler,
To understand the problem of hash collisions in Teradata, I will give a short overview of how rows are distributed in Teradata. If you are not familiar with Teradata Architecture or have forgotten the details, I recommend reading the following article first: As you already know, a table’s rows are distributed to the AMPs using
Both Teradata and Snowflake offer temporary tables. In this blog post, I’ll show you which types of tables Teradata and Snowflake provide, what similarities and differences they have. We will also look at table types that are only available in Teradata or only in Snowflake. I will show you what these can best be used
Often we have already reduced the size of our tables immensely using Multivalue Compression, and yet we need more space. Shrinking A Teradata Table To A Minimum Size I used once a simple trick for you that has allowed me to reduce a table already optimized with multivalue compression to 10% of its size. This
By way of introduction, I would like to mention that Teradata block-level compression is often performed by default nowadays. Therefore, this blog post’s considerations are only useful on Teradata systems, where this is not the case. Since Teradata Block Level Compression has been around, I often see that multi-value compression is not used. First, I
How Do I Select The Appropriate Data Type In Teradata? Datatype conversions are very costly and can require a lot of CPU on large tables. The wrong selection of datatypes has a negative effect on the execution plan. In this article, I will explain the details and how to get optimal performance from your queries
What is a Teradata Volatile Table? Volatile tables are very similar to derived tables, but their existence is not limited to their transaction; they stay materialized until the sessions in which they have been created ends. Volatile tables are created with the following syntax: CREATE VOLATILE TABLE Customer ( CustomerId INTEGER NOT NULL, LastName VARCHAR(255)
Teradata temporary tables come in different types and for different purposes. This article shows you the properties and uses of each one. 1. Derived Tables Are materialized by a select statement within a query Only exist within the time the query is executed Use the spool space of the executing user Disappear at the moment