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Netezza System Tables and Views

There are lot of Netezza system tables and views views available. You can get the more information about the users, tables, synonyms etc. Read: Netezza data types and length restrictions Netezza Query History details using nz_query_history Table Netezza System Tables and Views Below are the list of some commonly used system tables and views: View Table Description _v_sys_columns Return a list of all columns of table available in database. This is very important system view that can be used to search columns. _v_aggregate _t_aggregate Returns a list of all defined…

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September 4, 2016

Netezza

How to Resolve Netezza SPU Swap Partition Error

You might have seen Netezza SPU swap partition error when you are performing some complex transformation that may have included many large table with many complex join. This error does not mean that we have a space issue on any of our Netezza data slices or disks.We get his error when maximum available temporary work space is full. This temporary work space is used by all the temporary tables, sorting, aggregations, joining, implicit data skew (data distribution at run-time) etc. This issue may also occur if the query have cross…

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September 3, 2016

Netezza

Big Data Appliance Netezza Key Features

Netezza is an embedded and advanced analytics database. Netezza key features includes predict with more accuracy, deliver the predictions faster and respond rapidly to the any changes. IBM Netezza Analytics advanced technology supports data warehousing and in-database analytics into a scalable, high-performance, massively parallel advanced analytic platform that is designed to work with petascale data volumes. Below are the some of the Netezza Key features: Netezza bigdata appliance supports both, Business Intelligence and in-database advanced analytics. Lightning fast performance - scalable (10-100x) performance at petascale. Very Efficient even if being used…

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September 3, 2016

Netezza

List of Netezza Data Types and Best Practices

Data type is an attribute that specifies type of data of any object. Each column, variable and expression has related data type in SQL. However, different database offers the different data types for columns. Netezza data types are almost similar to what the traditional RDBMS supports. When you issue Netezza create table command each column in a database tables has to have name and a data type associated with it. The data type is based on the types of data which are stored inside the each column of the table.…

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September 2, 2016

Greenplum

Greenplum Encryption Options and Best Practices

To minimize the data breaches, now a day’s companies are increasingly adding security and cryptographic functions to their data at rest. This applies to the most of the big data appliances such as Greenplum, Netezza, Redshift etc. In this post we will see how the Greenplum encryption works. Greenplum support the data encryption at various level: Encrypting the Connections to the Database Encryption of data in Transit Encryption of data at Rest Database Connections Encryption In the Greenplum systems, connections between clients and the master database can be encrypted with SSL. This…

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September 1, 2016

Netezza

Netezza Date Functions and Examples

This article is about detailed descriptions and examples of the standard Netezza date functions that you can use to manipulate date columns in the Netezza SQL and Netezza stored procedure. In the real word scenarios many application manipulate the date and time data types. Date types are highly formatted and very complicated. Each date value contains the century, year, month, day, hour, minute, and second. Each RDBMS may employ different date functions, and there may also be differences in the syntax for each RDBMS even when the function call is the…

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August 31, 2016

General

Quick and best way to Compare Two Tables in SQL

Say you have requirement to compare two tables. You have two tables in same database or server that you wish to compare, and check if any changes in the column values or see if any row is missing in either of tables. Below are some of the methods you can use to compare two tables in SQL. Compare Two Tables using UNION ALL UNION allows you to compare data from two similar tables or data sets. It also handles the NULL values to other NULL values which JOIN or WHERE…

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August 29, 2016

Greenplum

Built-in Greenplum Analytics Functions and Examples

Window functions or Greenplum analytics functions compute an aggregated value that is based on a group of rows. These functions allow the application developers to more easily write complex online analytical processing (OLAP) queries using standard SQL commands. For example, with Greenplum analytics functions or windows expressions, users can calculate moving averages or sums over various intervals, ranks as selected column values etc. Read: Greenplum Computed Column Support and Alternative Greenplum Architecture Greeplum Analytic Functions Examples Here are the examples of some commonly used Greenplum analytics functions: COUNT Analytics functions…

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August 27, 2016

Greenplum

Greenplum Skew and How to Avoid it

Greenplum is a MPP shared nothing environment. Data is spread across the many segments located on the multiple segment hosts. If the data is distributed properly, no two segments in the system have same data. The even distribution of the data is determined by the column(s) provided in the DISTRIBUTED BY clause. Greenplum skew is the table situation that degrade the performance. System distributes the rows with same distribution values to same segment. Hence, the more the unique value in the distribution column, the better. In case if the data…

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August 25, 2016

Greenplum

Greenplum Interview Questions and Answers – Part1

Explain Greenplum Architecture. Read Post: Greenplum Architecture How data is distributed using hash algorithm? Read Post : How Greenplum Hash Distribution Works What are different ways to get data into Greenplum data warehouse? COPY FROM Gpload INSERT statement Create EXTERNAL TABLE Explain how data is stored in Greenplu? Data is stored based on selected field (s) which are used for distribution. When you have a Distribution Key by Hash the values of the Distribution Key are run through a Hash Formula. Then, a map is used to distribute the row to the…

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August 23, 2016