Netezza Planners: Different types of Planners

Netezza planners are very important to improve the performance of the query that you fire onto Netezza performance server. Types of Netezza Planners There are different types planners that Netezza performance server uses: The Fact Relationship (factrel) planner Snowflake planner The Star planner The Fact Relationship (factrel) planner The Fact Relation Planner is a feature used to prevent large table re-distribution i.e. costly re-distribution or broadcasting of fact data when other alternatives may exist. Read: Data warehouse Star schema and Design Analyze and Optimize Netezza Query Performance Netezza Best Performance…

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Netezza Organize On Syntax and Examples

The Netezza Organize on is one of important feature introduced in the Netezza data warehouse appliance. With the help of Organize on keys, you can create the clustered base tables (CBT). You can specify up to four columns in organize on key. Read: Cluster Based Tables - CBT Netezza TwinFin Architecture IBM Netezza nzsql Command and its Usage Netezza ALTER TABLE Command Netezza Organize On Keys IBM Netezza Organizing keys are useful for the more frequently used columns that you specify as keys are used in query predicates, alone or in…

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Improve performance with help of Netezza Query Plan

Netezza uses the cost based optimizer to determine the best methods for scan, join order and data movement between the SPUs. Planner uses the Netezza query plan to redistributed or broadcast your data. You can use EXPLAIN VERBOSE <your_quey> command to display the Netezza query plan. The planner always tries to avoid redistributing large tables because of the performance impact. Decisions about redistribution are made by the planner and are based on costs like expected table sizes. Optimizer also uses the Netezza query plan to dynamically rewrite queries to improve…

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Netezza External Table and Examples

A Netezza external table allows you to access the external file as a database table, you can join the external table with other database table to get required information or perform the complex transformations. External table script can be used to access the files that are stores on the host or on client machine. If the files are stored on the client machine, Netezza uses REMOTESOURCE option to access those files. Netezza External Table Syntax Below are the various syntax types that you can use to create external table in…

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Netezza Analytic Functions

Netezza analytic functions compute an aggregate value that is based on a group of rows. A Netezza SQL analytic function works on the group of rows and ignores the NULL in the dat.  Netezza server is basically an analytics system and provides many useful functions that can perform day to day aggregations. As these functions are native to Netezza server, hence use of these Netezza analytic functions improves performance of SQL queries as well as server performance. Frequently used Netezza analytical functions are as follows: COUNT Analytic Function Returns the number of…

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Collocated Joins in Netezza: Optimizing Query Performance

In Netezza, if two tables are distributed on same column then such tables are called collocated tables. If you join two collocated tables than each SPU in system works 100% independent to each other as the relevant rows required for joining these tables exist in the same SPU. These types of joins are called collocated joins. Collocated Joins Example Let’s take an examples, assume that we have two tables a patient and hospital, both are distributed on patient id. Netezza distributes the rows with same distribution key (column) to same…

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Analyze and Optimize Netezza Query Performance

Analyze and Optimize Netezza Query Performance is very important part if you are performing the reporting on top of Netezza or processing large amount of data. Netezza query tuning is very important part to improve performance. Netezza uses cost based optimizer to determine the best methods for scan and join operations, orders and redistribute or broadcast operations. Netezza system may redistribute the data for some situations like joins, grouping aggregates, create tables and when loading data into Netezza tables. System will decide the redistribution based on the cost like table…

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