Netezza

Netezza Joins and it’s Algorithms

Netezza joins combines the columns of the reports from the more than one table. SQL JOIN clause is used to combine rows from two or more tables, based on a common field between them. The best way to understand the Netezza joins is to get to know the SQL joins and then consider the algorithm that is used by database to resolve them. Read: Netezza nzsql Command and its Usage Netezza Generate Statistics: A Guide and Best Practices Commonly used Netezza Utilities Netezza Joins: Equi Join An equijoin is a join…

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August 14, 2016
Netezza

Netezza Generate Statistics: A Guide and Best Practices

Netezza uses the cost based optimizer to determine best methods determine redistribution, scan, join, join orders. The optimizer uses statistics information to determine the most efficient way to run a query. System uses the Netezza GENERATE STATISTICS command to generate information about each column proportion of the duplicate values,unique values, NULL values and the maximum and minimum values. How Statistics are collected? Netezza system collects statistics in various ways: Statistics are automatically generated for certain database operations Collect full statistics by running Netezza GENERATE STATISTICS command. This operation is required when table changes significantly, say…

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August 13, 2016
Netezza

Netezza nzsql Command and its Usage

The Netezza nzsql command invokes a SQL command interpreter on the Netezza host or any Unix/Linux system that can act as a edge node to connect to Netezza host. Read: Netezza Basic Commands Commonly used basic Netezza Linux Commands You can use the nzsql command to perform all the sql related stuffs. E.g. create database objects, run queries, and manage various databases created on that particular server. You cannot manage the object created in different host or server. Read: nzload Command and its Usage in Netezza Netezza nzsql Internal Slash…

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August 12, 2016