📁 Miscellaneous


Impala Miscellaneous Functions

Impala Conditions with Example Impala supports the following conditional functions for testing equality, comparison operators, and nullity: ‘Case’ Example: 1) If else select case when 20 > 10 then 20 else 15 end; Output: 20 2) If else if select case when 9 > 10 then 20 when 1 > 2 then 1.0 else 15 end; Output: 15 ===================================================================================== ‘Coalesce’ Function Example: The COALESCE function in Impala returns the first […]


PMD (Programming Mistake Detector)

PMD (Programming Mistake Detector) What is PMD? PMD aka Programming Mistake Detector is Java Source Code Analyzer. It is used to clean erroneous code in our java projects based on predefined set of rules. PMD supports the ability to write custom rules. Issues reported by PMD may not be true errors always, but rather inefficient code, i.e. the application could still function properly even if they were not corrected. PMD […]


Creating UDF and UDAF for Impala

Installing the UDF Development Package

The output will be like below code. [cloudera@quickstart impala-udf-samples-master]$ cmake . — The C compiler identification is GNU 4.4.7 — The CXX compiler identification is GNU 4.4.7 — Check for working C compiler: /usr/bin/cc — Check for working C compiler: /usr/bin/cc — works — Detecting C compiler ABI info — Detecting C compiler ABI info – done — Check for working CXX compiler: /usr/bin/c++ […]


Postgres Commands

CREATE

We can see our new table by typing this:

List of relations Schema | Name | Type | Owner ——–+————+——-+———- public | playground | table | postgres (1 row) INSERT

  Message returned if only one row was inserted. oid is the numeric OID of the inserted row. Ex: INSERT oid 1 Message returned if more than one rows were inserted. # is the number of rows […]


Impala Best Practices 1

Below are Impala performance tuning options: Pre-execution Checklist Data types Partitioning File Format Data Type Choices Define integer columns as INT/BIGINT Operations on INT/BIGINT more efficient than STRING Convert “external" data to good “internal" types on load e.g. CAST date strings to TIMESTAMPS This avoids expensive CASTs in queries later Partitioning The fastest I/O is the one […]


Apache Storm Integration With Apache Kafka

Installing Apache Storm The prerequisite for storm to work on the machine. a. Download and installation commands for ZeroMQ 2.1.7: Run the following commands on terminals

b. Download and installation commands for JZMQ: