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Avro >> mail # user >> Using Arrays in Apache Avro


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Raihan Jamal 2013-09-24, 18:02
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Mika Ristimaki 2013-09-24, 18:40
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Re: Using Arrays in Apache Avro
Thanks a lot Mika. Yeah, it works now but my second question is- Does the
avro schema that I have made looks good as compared to JSON value that we
were using previously?
I thought we can use an array for that so designed like that using an
Apache Avro..

And also why Avro Array uses java.util.List datatype? Just curious to know
on that as well.

Thanks for the help.

*Raihan Jamal*
On Tue, Sep 24, 2013 at 11:40 AM, Mika Ristimaki
<[EMAIL PROTECTED]>wrote:

> Hi,
>
> Avro array uses java.util.List datatype. So you must do something like
>
> List<Double> nums = new ArrayList<Double>();
> nums.add(new Double(9.97));
> .
> .
>
> On Sep 24, 2013, at 9:02 PM, Raihan Jamal <[EMAIL PROTECTED]> wrote:
>
> Earlier, I was using JSON in our project so one of our attribute data
> looks like below in JSON format. Below is the attribute `e3` data in JSON
> format.
>  {"lv":[{"v":{"prc":9.97}},{"v":{"prc":5.56}},{"v":{"prc":21.48}}]}
>  Now, I am planning to use Apache Avro for our Data Serialization format.
> So I decided to design the Avro schema for the above attributes data. And I
> came up with the below design.
>
>   {
>      "namespace": "com.avro.test.AvroExperiment",
>      "type": "record",
>      "name": "AVG_PRICE",
>      "doc": "AVG_PRICE data",
>      "fields": [
>          {"name": "prc", "type": {"type": "array", "items": "double"}}
>      ]
>     }
>
> Now, I am not sure whether the above schema looks right or not
> corresponding to the values I have in JSON? Can anyone help me on that?
> Assuming the above schema looks correct, if I try to serialize the data
> using the above avro schema, I always get the below error-
>
> double[] nums = new double[] { 9.97, 5.56, 21.48 };
>  Schema schema = new
> Parser().parse((AvroExperiment.class.getResourceAsStream("/aspmc.avsc")));
>  GenericRecord record = new GenericData.Record(schema);
> record.put("prc", nums);
>  GenericDatumWriter<GenericRecord> writer = new
> GenericDatumWriter<GenericRecord>(schema);
> ByteArrayOutputStream os = new ByteArrayOutputStream();
>
> Encoder e = EncoderFactory.get().binaryEncoder(os, null);
>  // this line gives me exception..
>  writer.write(record, e);
> Below is the exception, I always get-
>
> *    Exception in thread "main" java.lang.ClassCastException: [D
> incompatible with java.util.Collection*
>  Any idea what wrong I am doing here?
>
>
>
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Mika Ristimaki 2013-09-24, 19:20
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graham sanderson 2013-09-24, 19:42
NEW: Monitor These Apps!
elasticsearch, apache solr, apache hbase, hadoop, redis, casssandra, amazon cloudwatch, mysql, memcached, apache kafka, apache zookeeper, apache storm, ubuntu, centOS, red hat, debian, puppet labs, java, senseiDB