Return-Path: X-Original-To: apmail-avro-user-archive@www.apache.org Delivered-To: apmail-avro-user-archive@www.apache.org Received: from mail.apache.org (hermes.apache.org [140.211.11.3]) by minotaur.apache.org (Postfix) with SMTP id 427DAFE08 for ; Sat, 6 Apr 2013 20:36:26 +0000 (UTC) Received: (qmail 99375 invoked by uid 500); 6 Apr 2013 20:36:26 -0000 Delivered-To: apmail-avro-user-archive@avro.apache.org Received: (qmail 99310 invoked by uid 500); 6 Apr 2013 20:36:25 -0000 Mailing-List: contact user-help@avro.apache.org; run by ezmlm Precedence: bulk List-Help: List-Unsubscribe: List-Post: List-Id: Reply-To: user@avro.apache.org Delivered-To: mailing list user@avro.apache.org Received: (qmail 99302 invoked by uid 99); 6 Apr 2013 20:36:25 -0000 Received: from minotaur.apache.org (HELO minotaur.apache.org) (140.211.11.9) by apache.org (qpsmtpd/0.29) with ESMTP; Sat, 06 Apr 2013 20:36:25 +0000 Received: from localhost (HELO [192.168.2.181]) (127.0.0.1) (smtp-auth username scottcarey, mechanism login) by minotaur.apache.org (qpsmtpd/0.29) with ESMTP; Sat, 06 Apr 2013 20:36:25 +0000 User-Agent: Microsoft-MacOutlook/14.3.2.130206 Date: Sat, 06 Apr 2013 13:36:17 -0700 Subject: Re: Issue writing union in avro? From: Scott Carey Sender: Scott Carey To: "user@avro.apache.org" Message-ID: Thread-Topic: Issue writing union in avro? In-Reply-To: Mime-version: 1.0 Content-type: multipart/alternative; boundary="B_3448100185_9108371" > This message is in MIME format. Since your mail reader does not understand this format, some or all of this message may not be legible. --B_3448100185_9108371 Content-type: text/plain; charset="US-ASCII" Content-transfer-encoding: 7bit This is due to using the JSON encoding for avro and not the binary encoding. It would appear that the Python version is a little bit lax on the spec. Some have built variations of the JSON encoding that do not label the union, but there are drawbacks to this too, as the type can be ambiguous in a very large number of cases without a label. Why are you using the JSON encoding for Avro? The primary purpose of the JSON serialization form as it is now is for transforming the binary to human readable form. Instead of building your GenericRecord from a JSON string, try using GenericRecordBuilder. -Scott On 4/5/13 4:59 AM, "Jonathan Coveney" wrote: > Ok, I figured out the issue: > > If you make string c the following: > String c = "{\"name\": \"Alyssa\", \"favorite_number\": {\"int\": 256}, > \"favorite_color\": {\"string\": \"blue\"}}"; > > Then this works. > > This represents a divergence between the python and the Java implementation... > the above does not work in Python, but it does work in Java. And of course, > vice versa. > > I think I know how to fix this (and can file a bug with my reproduction and > the fix), but I'm not sure which one is the expected case? Which > implementation is wrong? > > Thanks > > > 2013/4/5 Jonathan Coveney >> Correction: the issue is when reading the string according to the avro >> schema, not on writing. it fails before I get a chance to write :) >> >> >> 2013/4/5 Jonathan Coveney >>> I implemented essentially the Java avro example but using the >>> GenericDatumWriter and GenericDatumReader and hit an issue. >>> >>> https://gist.github.com/jcoveney/5317904 >>> >>> This is the error: >>> Exception in thread "main" java.lang.RuntimeException: >>> org.apache.avro.AvroTypeException: Expected start-union. Got >>> VALUE_NUMBER_INT >>> at com.spotify.hadoop.mapred.Hrm.main(Hrm.java:45) >>> Caused by: org.apache.avro.AvroTypeException: Expected start-union. Got >>> VALUE_NUMBER_INT >>> at org.apache.avro.io.JsonDecoder.error(JsonDecoder.java:697) >>> at org.apache.avro.io.JsonDecoder.readIndex(JsonDecoder.java:441) >>> at >>> org.apache.avro.io.ResolvingDecoder.doAction(ResolvingDecoder.java:229) >>> at org.apache.avro.io.parsing.Parser.advance(Parser.java:88) >>> at >>> org.apache.avro.io.ResolvingDecoder.readIndex(ResolvingDecoder.java:206) >>> at >>> org.apache.avro.generic.GenericDatumReader.read(GenericDatumReader.java:152) >>> at >>> org.apache.avro.generic.GenericDatumReader.readRecord(GenericDatumReader.jav >>> a:177) >>> at >>> org.apache.avro.generic.GenericDatumReader.read(GenericDatumReader.java:148) >>> at >>> org.apache.avro.generic.GenericDatumReader.read(GenericDatumReader.java:139) >>> at com.spotify.hadoop.mapred.Hrm.main(Hrm.java:38) >>> >>> Am I doing something wrong? Is this a bug? I'm digging in now but am curious >>> if anyone has seen this before? >>> >>> I get the feeling I am working with Avro in a way that most people do not :) >>> >> > --B_3448100185_9108371 Content-type: text/html; charset="US-ASCII" Content-transfer-encoding: quoted-printable
This is due to using the JSO= N encoding for avro and not the binary encoding.  It would appear that = the Python version is a little bit lax on the spec.  Some have built va= riations of the JSON encoding that do not label the union, but there are dra= wbacks to this too, as the type can be ambiguous in a very large number of c= ases without a label.

Why are you using the JSON en= coding for Avro?  The primary purpose of the JSON serialization form as= it is now is for transforming the binary to human readable form. 
Instead of building your GenericRecord from a JSON string, try using G= enericRecordBuilder. 

-Scott

On 4/5/13 4:59 AM, "Jonathan Co= veney" <jcoveney@gmail.com> wr= ote:

Ok, I figured out the issue:

If you make string c the following:
String c =3D "{\"name\": \"Alyssa\", \"favorite_number\": {\"int\": 256}, \"f= avorite_color\": {\"string\": \"blue\"}}";

Then this works.

This represents a divergence between the python and the Java implementation= ... the above does not work in Python, but it does work in Java. And of cour= se, vice versa.

I think I know how to fix this (and can file a bug with my reproduction and= the fix), but I'm not sure which one is the expected case? Which implementa= tion is wrong?

Thanks


2= 013/4/5 Jonathan Coveney <jcoveney@gmail.com>
Correction: the issue is when reading the string acco= rding to the avro schema, not on writing. it fails before I get a chance to = write :)


2013/4/5 Jonathan Coveney <jcoveney@gmail.com= >
I implemented es= sentially the Java avro example but using the GenericDatumWriter and Generic= DatumReader and hit an issue.
This is the error:
Exception in thread "main" java.lang.RuntimeException: org.apache.avro.Avro= TypeException: Expected start-union. Got VALUE_NUMBER_INT
    at com.spotify.hadoop.mapred.Hrm.main(Hrm.java:45)
Caused by: org.apache.avro.AvroTypeException: Expected start-union. Got VAL= UE_NUMBER_INT
    at org.apache.avro.io.JsonDecoder.error(JsonDecoder.java= :697)
    at org.apache.avro.io.JsonDecoder.readIndex(JsonDecoder.= java:441)
    at org.apache.avro.io.ResolvingDecoder.doAction(Resolvin= gDecoder.java:229)
    at org.apache.avro.io.parsing.Parser.advance(Parser.java= :88)
    at org.apache.avro.io.ResolvingDecoder.readIndex(Resolvi= ngDecoder.java:206)
    at org.apache.avro.generic.GenericDatumReader.read(Gener= icDatumReader.java:152)
    at org.apache.avro.generic.GenericDatumReader.readRecord= (GenericDatumReader.java:177)
    at org.apache.avro.generic.GenericDatumReader.read(Gener= icDatumReader.java:148)
    at org.apache.avro.generic.GenericDatumReader.read(Gener= icDatumReader.java:139)
    at com.spotify.hadoop.mapred.Hrm.main(Hrm.java:38)



--B_3448100185_9108371--