How does compression work in Teradata?

Compression is used to reduce the storage used by the tables. In Teradata, compression can compress up to 255 distinct values including NULL. Since the storage is reduced, Teradata can store more records in a block. This results in improved query response time since any I/O operation can process more rows per block.

Which compression can be activated outside of the Create Table statement?

In case of MVC and ALC values need to be define in CREATE TABLE statement, But BLC is activated outside of table definition.

What is Multi value compression in Teradata?

Multivalue compression(MVC) is widely used in Teradata,It allows the users to compress the most commonly appearing values in one or more columns.

What is block level compression in Teradata?

Block Level Compression (BLC) is a feature introduced with Teradata 13.10 and allows for compression of entire data blocks, contrary to other compression methods applied on column level (MVC, ALC). Only the data blocks containing rows are compressed.

What is PPI in Teradata?

Partitioned Primary Index (PPI) is an indexing mechanism in Teradata Database. PPI is used to improve performance for large tables when you submit queries that specify a range constraint. PPI allows you to reduce the number of rows to be processed by using partition elimination.

What is join index in Teradata?

JOIN INDEX is a materialized view. Its definition is permanently stored and the data is updated whenever the base tables referred in the join index is updated. JOIN INDEX may contain one or more tables and also contain pre-aggregated data. Join indexes are mainly used for improving the performance.

How does block compression work?

How Does Block Compression Work? Block compression is a technique for reducing the amount of memory required to store color data. By storing some colors in their original size, and other colors using an encoding scheme, you can dramatically reduce the amount of memory required to store the image.

How do I change PPI in Teradata?

Teradata ALTER PPI Performance

CREATE MULTISET TABLE PPI_Test. (
ALTER TABLE PPI_Test MODIFY PRIMARY INDEX ADD RANGE BETWEEN DATE ‘2016-01-01’ AND DATE ‘2016-12-31’ EACH INTERVAL ‘1’ DAY;
CREATE MULTISET TABLE PPI_Test_Copy.

What is FastLoad in Teradata?

Teradata FastLoad is used to load a large amount of data in an empty table on a Teradata System or load data from the client to the Database system. It allows fast loading of a single empty table with no SIs, JIs, HIs, or RI (FKs) or column partitioning.

What is materialized table in Teradata?

A materialized view (MV) is a cross between a view and an index. It is like an index in the way that it is used automatically by the database system to improve the performance of a query. Teradata refers to the materialized view structure by the term “Join Index”, a name that reflects its similarity to indexes.

What is block compression in Teradata?

What is block compression?

Block compression is a texture compression technique for reducing texture size. When compared to a texture with 32-bits per color, a block-compressed texture can be up to 75 percent smaller. Applications usually see a performance increase when using block compression because of the smaller memory footprint.

How is block level compression used in Teradata?

Block Level Compression (BLC) in Teradata. Block Level Compression (BLC) is a space reduction technique in Teradata. It has been introduced in 13.10 and is used to apply compression to all the permanent data blocks in a table. The compression rate can be achieved by this technique is 60% on an average.

How are data blocks stored in Teradata point?

Data is stored in the disk array in the form of data blocks and this data blocks are stored in the cylinder. Currently Teradata uses Lempel-Ziv algorithm for block level compression. After applying the BLC, each cylinder will hold more numbers of data blocks in it. To know about Lempel-Ziv algorithm refer to Lempel-Ziv Compression Technique.

How does block level compression ( BLC ) work?

The compression rate can be achieved by this technique is 60% on an average. How BLC works? Data is stored in the disk array in the form of data blocks and this data blocks are stored in the cylinder.

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