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Templeton provides a REST-like web API for HCatalog and related Hadoop components. Developers can make HTTP requests to the Templeton web server to execute HCatalog DDL commands. With the REST APIs in place for HCatalog DDL commands, it is desirable to have a JAVA APIs in HCAT which can help end users to execute DDL commands without using CLI.

Design

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New Classes

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This class is a sub class of HCatCommandDesc and will be used by the users to create descriptor and validate it for the "create table" command.

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HCatCreateDBDesc

This class is a sub class of HCatCommandDesc and will be used by the users to create descriptors and validate it for the "create database" command.

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HCatAddPartitionDesc

This class is a sub class of HCatCommandDesc and will be used by the users to create descriptos and validate it for the "add partition" command.

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HCatTable

This class encapsulates the table information returned the HCatClient implementation class and provides a uniform view to the user.

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HCatDatabase

This class encapsulates the database information returned the HCatClient implementation class and provides a uniform view to the user.

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HCatPartition

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Usage

 Configuration config = new Configuration();
 config.add("hive-site.xml");
 HCatClient client = HCatClient.create(config);

 HCatCreateTableDesc desc = new HCatCreateTableDesc();
 desc.setTableName("demo_table");
 desc.setDatabaseName("db1");
 desc.setFileFormat("rcfile");
 ArrayList<HCatFieldSchema> cols = new ArrayList<HCatFieldSchema>();
 cols.add(new HCatFieldSchema("col1", Type.INT, "comment1"));
 cols.add(new HCatFieldSchema("col2", Type.STRING, "comment2"));
 desc.setCols(cols);

 //Validate
 desc.validateCommandDesc();
 boolean success = client.createTable(desc);

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