Importing data from Sqoop into Hive External Table with Avro encoding

I wanted to figure out how to import content of RDBMS table into Hive with Avro encoding, during this process i wanted to use external hive tables so that i have complete control over the location of files.
Note: I have a different/easier method for doing this in Importing data from Sqoop into Hive External Table with Avro encoding updated
First i did create following table in the mysql database which is on the same machine as that of my HortonWorks Sandbox
  1. First create CUSTOMER table like this in mysql
    
    CREATE TABLE CUSTOMER (       
    contactid INTEGER NOT NULL ,       
    firstname VARCHAR(50),       
    lastname  VARCHAR(50),       
    email varchar(50) );
    
  2. After creating table add couple of records in it by executing following insert statement insert into customer values(1,'Sachin','Tendulark','sachin@gmail.com');
  3. Next step is to run sqoop query that downloads records of the table into HDFS at /tmp/customer/sample. In real world you might want to download only first 10 records or so into Hive, because you need few sample records just to create avro schema
    
    sqoop import --connect jdbc:mysql://localhost/test --table CUSTOMER --username sqoop1 
    --password sqoop -m 1 --create-hive-table 
    --hive-table CONTACT --as-avrodatafile  --target-dir /tmp/customer/sample
    
  4. Running sqoop command it will dump records in HDFS, so first download the avro file generated by sqoop
    
    hdfs dfs -get /tmp/customer/sample/part-m-00000.avro
    
  5. Use the avro-tools-*.jar, to read schema of the file generated by sqoop. by executing following command
    
    java -jar avro-tools-1.7.5.jar getschema part-m-00000.avro > customer.avsc
    
    This is how the customer.avsc file looks like in my case
    
    {
      "type" : "record",
      "name" : "CUSTOMER",
      "doc" : "Sqoop import of CUSTOMER",
      "fields" : [ {
        "name" : "contactid",
        "type" : [ "int", "null" ],
        "columnName" : "contactid",
        "sqlType" : "4"
      }, {
        "name" : "firstname",
        "type" : [ "string", "null" ],
        "columnName" : "firstname",
        "sqlType" : "12"
      }, {
        "name" : "lastname",
        "type" : [ "string", "null" ],
        "columnName" : "lastname",
        "sqlType" : "12"
      }, {
        "name" : "email",
        "type" : [ "string", "null" ],
        "columnName" : "email",
        "sqlType" : "12"
      } ],
      "tableName" : "CUSTOMER"
    }
    
  6. Next step is to upload the avro schema file that you created in the last step back to HDFS, in my case i had HDFS folder called /tmp/customer/schema and i uploaded the avro schema file in it
    
    hdfs dfs -put customer.avsc /tmp/customer/schema/
    
  7. Now go to hive and execute the following command to define External Customer Hive table with avro schema defined in last step
    
    CREATE EXTERNAL TABLE CUSTOMER
    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'
    LOCATION '/tmp/customer/data'
    TBLPROPERTIES ('avro.schema.url'='hdfs:///tmp/customer/schema/customer.avsc');
    
  8. Last step is to run sqoop again but this time with all the data in the external directory that Customer hive table is pointing to.
    
    sqoop import --connect jdbc:mysql://localhost/test --table CUSTOMER --username sqoop1 
    --password sqoop -m 1 --as-avrodatafile 
     --target-dir /tmp/customer/data --compression-codec snappy
    
Now if you run select query on the CUSTOMER table you should be able to get all the data that you see in your RDBMS

9 comments:

Anonymous said...

hi sunil,
while trying to run the commands as you described in your blog.
getting error as below
"Error: Unable to access jarfile avro-tools..."

can you please help me out to identify the reason or m i missing any configurations?

phanikb said...

You need to download avro-tools.jar for internet and need to move to the directory where you want to trigger that above command.

bharat batra said...

I am not able to read the data from customer no class found error org/serial/snappy/Snappy.
Anyone please advise.

wirawan0 said...

I thought AVRO format must be used in conjunction to its schema, not by itself. In other word, I was not expecting AVRO to be self-descripting by storing the schema inside the file. Am I wrong here? Since one of the commands above demonstrated that there is a tool to extract the schema out from the AVRO file.

Sameer said...

Nice Article. thanks!!

Srividya Parthasarathy said...

good one to poc avro...

Vamsi Krishna said...

what is the purpouse of [--create-hive-table and--hive-table CONTACT] in step 3 in sqoop command?we are not importing any data into hive table.Just we are generating schema file based on sample data.where you are using this contact[hive table] in your post.

Vamsi Krishna said...
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Barış Taşkend said...
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