HCatalog Basics
- HCatalog is an extension of Hive, that exposes the Hive metadata to other tools and frameworks.
- To define a HCatalog schema, one simply needs to define a table in Hive.
- The usefulness of HCatalog is, when one needs to expose the schema outside of Hive i.e to other frameworks - ex : Pig
- To load a table student, managed by HCatalog:
- stu_table= LOAD 'student' USING org.apache.hcatalog.pig.HCatLoader();
- the schema of stu_table is whatever the schema of student is.
- Similarly, to store we use :
- STORE stu_table INTO 'student' USING org.apache.hcatalog.pig.HCatStorer();
- Using PIG shell, we can run Hive DDL command.
- grunt> sql create table movies (
- title string,
- rating string,
- length double)
- partitioned by (genre string)
- stored as ORC;
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