Convert CSV Data to Avro Data
Convert CSV Data to Avro Data
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In one of my previous posts 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 the steps below:
- Create a Hive table stored as textfile and specify your csv delimiter also.
- Load csv file to above table using "load data" command.
- Create another Hive table using AvroSerDe.
- Insert data from former table to new Avro Hive table using "insert overwrite" command.
To demonstrate this I will use use the data below (student.csv):
0,38,91
0,65,28
0,78,16
1,34,96
1,78,14
1,11,43
Now execute below queries in Hive:
--1. Create a Hive table stored as textfile USE test; CREATE TABLE csv_table ( student_id INT, subject_id INT, marks INT) ROW FORMAT DELIMITED FIELDS TERMINATED BY ',' STORED AS TEXTFILE; --2. Load csv_table with student.csv data LOAD DATA LOCAL INPATH "/path/to/student.csv" OVERWRITE INTO TABLE test.csv_table; --3. Create another Hive table using AvroSerDe CREATE TABLE avro_table ROW FORMAT SERDE 'org.apache.hadoop.hive.serde2.avro.AvroSerDe' STORED AS INPUTFORMAT 'org.apache.hadoop.hive.ql.io.avro.AvroContainerInputFormat' OUTPUTFORMAT 'org.apache.hadoop.hive.ql.io.avro.AvroContainerOutputFormat' TBLPROPERTIES ( 'avro.schema.literal'='{ "namespace": "com.rishav.avro", "name": "student_marks", "type": "record", "fields": [ { "name":"student_id","type":"int"}, { "name":"subject_id","type":"int"}, { "name":"marks","type":"int"}] }'); --4. Load avro_table with data from csv_table INSERT OVERWRITE TABLE avro_table SELECT student_id, subject_id, marks FROM csv_table;
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.
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Published at DZone with permission of Rishav Rohit , DZone MVB. See the original article here.
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