Netezza

Netezza Create Table Command and Examples

Use the Netezza CREATE TABLE command to create a new, initially empty table in the current database. The CREATE TABLE command automatically creates a data type that represents the tuple type (structure type) corresponding to one row of the table. Netezza Create Table Command Syntax CREATE [ TEMPORARY | TEMP ] TABLE <table> ( <col> <type> [<col_constraint>][,<col> <type> [<col_constraint>]…] [<table_constraint>[,<table_constraint>… ] ) [ DISTRIBUTE ON { RANDOM | [HASH] (<col>[,<col>…]) } ] [ ORGANIZE ON { (<col>) | NONE } ] [ ROW SECURITY ] Read: Importance of right Distribution…

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November 8, 2016
Netezza

Netezza Failover – High Availability Architecture

Netezza appliance include necessary components to function seamlessly in the event of any hardware issue so that its availability is more that 99.99%. This is called Netezza high availability architecture that perform seamlessly in case of Netezza failover. There are two host in a cluster in all Netezza appliances so that if one fails other once can take over the task that is being carried out. Netezza Failover - High Availability Architecture Overview Netezza appliance uses the Linux-HA (high availability) and Distributed Replicated Block Device (DRBD) for the host cluster…

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October 31, 2016
Netezza

Changing Netezza Table Distribution key and Example

Choosing right distribution key is one of the important factor to improve the performance of Netezza server. If you have created the table with RANDOM distribution or with different column with lots of duplicate records then you should immediately change the distribution key otherwise that will reduces the performance. Changing Netezza table distribution key is process of redistributing the Netezza table using Netezza nzsql. Changing Netezza Table Distribution key and Example You can achieve the redistribution in couple of ways: Redistribute using CTAS Creating new table and loading data at…

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October 15, 2016
Netezza

Netezza Best Practices to Improve Performance

Today there is a increased demand in advanced analytics on big data. Netezza is designed with built in functionalities to perform advanced analytics on really big data sets. To improve the performance, you should follow some Netezza best practices. Best practice should not mean hundreds of rules and regulations to follow. Recommended that basic principles are followed on following features of Netezza: Distribution Data types Statistics Zone maps Clustered base tables Groom table command Netezza Best Practices on Distributions In a Netezza data warehouse appliance good distribution is fundamental element…

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October 2, 2016
Netezza

Netezza Internal DataTypes: rowid, createxid, deletexid and datasliceid

Netezza supports internal datatypes that are used by system to perform internal tasks on the table records. Netezza internal datatypes includes: rowid, transaction ID (createxid, deletexid), and dataslice. Shows Netezza internal Datatypes: Internal Datatype Column Name rowid rowid transaction ID Createxid deletexid dataslice datasliceid Netezza Internal DataTypes: Rowid Identifies a specific and unique record in the database. These row numbers are not necessarily sequential within a table. Usually, the initial rowid value is 100,000. The Netezza host assigns a range of sequential rowids to each SPU in the system. When…

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September 23, 2016
Netezza

Netezza Hash Function Usage and Examples

You can use Netezza hash function to encode the data by transforming the input into a hash code or hash values. If you use the hash function, no two inputs have same hash values. The hash algorithm is designed to minimise the collision (two inputs having same hash value). You can use the hash function to speed up the data record retrieval by using simple one way lookup. Hash code is used as an index into a hash table which has a pointer to data records. Netezza hash function also…

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September 14, 2016
Netezza

Netezza Skew and How to avoid it

You will hear a lot about "Netezza Skew" if you are developing data warehouse on Netezza, Redshift, Teradata, hive or Impala database. The performance of the system is directly linked to uniform distribution of the user data  across all of the data slices in the system. When you create a table and then load the data into the system, the rows of the table should be distributed uniformly among all the data slices. If some data slices have more rows of a table than others this scenarios is called skew.…

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July 6, 2016
Netezza

Importance of right Netezza Distribution key

This post is all about how data is distributed (Netezza distribution key) in Netezza server. Feel free to make comments or suggestions to improve it, or pass it on if you like. Let’s first understand how NPS stores the data on disk drives. Each Snippet Processor in the Snippet Processing Unit (SPU) has a dedicated hard drive has its separate CPU, FPGA, separate RAM memory, hard disks  and the data on stored on drive is called a data slice. Read: Changing Netezza Table Distribution Key Cluster Based Tables (CBT) in…

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July 6, 2016