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Getting started with Hadoop using Kognitio Console (part 2)

by MikeAtkinson » Tue Jun 14, 2016 3:26 pm

In Part 1 we saw how to create a HDFS_CON connector to create a bridge between the Kognitio Analytical Platform and the Hadoop system it is running on. In this post we look at how to use Console to browse Hadoop data and create an external table from that data.

Using the External Data Source.

Open the External Data Sources item in the metadata tree (this might take a while) and data sources available to the user will be shown, in this case hdfs_data which we created in part 1.

Double-click on the External Data Source and the data browser will be opened. This allows navigation of the hadoop tree and examination of files

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On navigation down to /user/presales there is a small file test.csv, bringing up the pop-up menu on this.

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Clicking on "view file" shows the contents of the file in the right hand pane.

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Create external table

Clicking on "Create external table" brings up the "Create External Table" dialog, it may take some time to read a sample of the data and then it profiles that sample to suggest column definitions.

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Clicking the "More Options" button brings up tabs which allow the sampling, data format and connector parameters (which are used to access the data) to be changed.

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You can also change the table name (which is guessed at from the file name), schema, and column definitions.

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On selecting "OK" the external table is created.

Using the external table

The external table can then the accessed like any other table using SQL.

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A view of the table may be created and by right clicking on the view and selecting "Create view image" a dialog is shown which allows view images of various types to be shown.

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This view can then be accessed much faster than the underlying table.

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