Thursday, 27 February 2014

Convert csv data to Avro data

In one of my previous post I explained how we can convert json data to avro data and vice versa using avro tools command line option. Today I was trying to see what options we have for converting csv data to avro format, as of now we don't have any avro tool option to accomplish this . Now, we can either write our own java program (MapReduce program or a simple java program) or we can use various SerDe's available with Hive to do this quickly and without writing any code :)

To convert csv data to Avro data using Hive we need to follow below steps:
  1. Create a Hive table stored as textfile and specify your csv delimiter also.
  2. Load csv file to above table using "load data" command.
  3. Create another Hive table using AvroSerDe.
  4. Insert data from former table to new Avro Hive table using "insert overwrite" command.

To demonstrate this I will use use below data (student.csv):
Now execute below queries in Hive:

Now you can get data in Avro format from Hive warehouse folder. To dump this file to local file system use below command:
hadoop fs -cat /path/to/warehouse/test.db/avro_table/* > student.avro

If you want to get json data from this avro file you can use avro tools command:
java -jar avro-tools-1.7.5.jar tojson student.avro > student.json

So we can easily convert csv to avro and csv to json also by just writing 4 HQLs.


  1. Nice post Rohit, with avro can you change the schema after the table is created? Let's say I got a new column to the existing data source, can I update the avro schema??

    1. not very sure if we can alter avro_table. you can try this out