Netezza Joins Archives

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…

Comments Off

September 3, 2016

Netezza

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…

2 Comments

August 16, 2016

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…

Comments Off

August 14, 2016