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course: ksqlDB 101

Hands On: Converting Data Formats with ksqlDB

2 min
Allison

Allison Walther

Integration Architect (Presenter)

Hands On: Converting Data Formats with ksqlDB

This exercise will teach you how to change data formats in ksqlDB.

Inspect Your Existing Data

  1. Begin by printing your orders_flat stream from Hands On: Flatten Nested Records with ksqlDB to show the existing JSON data:

    PRINT orders_flat FROM BEGINNING;

    Click Run query.

  2. Stop the query. Then expand a record to see the JSON structure.

Change Your Data's Format and Inspect It Again

  1. Enter a CREATE STREAM AS statement, with VALUE_FORMAT set to delimited:

    CREATE STREAM orders_csv
WITH(VALUE_FORMAT='delimited', KAFKA_TOPIC='orders_csv') AS
SELECT * FROM orders_flat EMIT CHANGES;

    Click Run query. This will help to clean up the JSON you saw in Step 2.

  2. Run a PRINT statement to see your newly delimited data:

    PRINT orders_csv FROM BEGINNING;

    Click Run query, then scroll down and expand a record to see the comma-delimited fields.

    It's as easy as that: VALUE_FORMAT helps you to change formats within ksqlDB.

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Total 28

  1. Introduction to ksqlDB
    2 min
  2. Interacting with ksqlDB
    2 min
  3. Hands On: Interacting with ksqlDB
    5 min
  4. Creating, Exporting, and Importing Data
    2 min
  5. Filtering with ksqlDB
    1 min
  6. Hands On: Filtering with ksqlDB
    1 min
  7. Lookups and Joins with ksqlDB
    2 min
  8. Hands On: Lookups and Joins with ksqlDB
    2 min
  9. Transforming Data with ksqlDB
    2 min
  10. Hands On: Transforming Data with ksqlDB
    2 min
  11. Flatten Nested Records with ksqlDB
    1 min
  12. Hands On: Flatten Nested Records with ksqlDB
    2 min
  13. Converting Data Formats with ksqlDB
    2 min
  14. Hands On: Converting Data Formats with ksqlDB
    2 min
  15. Merging Two Streams with ksqlDB
    1 min
  16. Hands On: Merging Two Streams with ksqlDB
    2 min
  17. Splitting Two Streams with ksqlDB
    2 min
  18. Hands On: Splitting Two Streams with ksqlDB
    2 min
  19. Streams and Tables
    2 min
  20. Stateful Aggregations (Materialized Views)
    2 min
  21. Hands On: Stateful Aggregations (Materialized Views)
    2 min
  22. Push Queries and Pull Queries
    2 min
  23. Hands On: Push Queries and Pull Queries
    2 min
  24. Under the Covers of ksqlDB
    2 min
  25. ksqlDB Code Lifecycle
    2 min
  26. Apply Lambda Functions to Arrays and Maps
    2 min
  27. Hands On: Apply Lambda Functions to Arrays and Maps
    2 min
  28. Monitoring ksqlDB
    1 min

Related Resources

Presentation

Inside ksqlDB

Tutorial

How To Convert a Stream's Serialization Format

Docs

Schema Registry Integration

Docs

Serialization

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Hands On: Converting Data Formats with ksqlDB

In this exercise, we'll work with changing data formats. The first thing that we're gonna want to do is print out this orders_flat stream to show the existing JSON data. KsqlDB formats it pretty poorly. Let's expand a record to see the JSON structure. Go ahead and enter a create stream as statement with the value format specified to delimit it. This will help clean up that JSON structure we saw earlier. Run the query. Now let's run a print orders_CSV statement to show our newly delimited data. Again, scroll down and expand a record to show the comma-delimited fields. And it's as easy as that. Value format helps you change between different formats within ksqlDB.