You are viewing a plain text version of this content. The canonical link for it is here.
Posted to users@kafka.apache.org by Shone Sadler <sh...@gmail.com> on 2013/06/12 16:14:42 UTC
Versioning Schema's
Hello everyone,
After doing some searching on the mailing list for best practices on
integrating Avro with Kafka there appears to be at least 3 options for
integrating the Avro Schema; 1) embedding the entire schema within the
message 2) embedding a unique identifier for the schema in the message and
3) deriving the schema from the topic/resource name.
Option 2, appears to be the best option in terms of both efficiency and
flexibility. However, from a programming perspective it complicates the
solution with the need for both an envelope schema (containing a "schema
id" and "bytes" field for record data) and message schema (containing the
application specific message fields). This requires two levels of
serialization/deserialization.
Questions:
1) How are others dealing with versioning of schemas?
2) Is there a more elegant means of embedding a schema ids in a Avro
message (I am new to both currently ;-)?
Thanks in advance!
Shone
Re: Versioning Schema's
Posted by David Arthur <mu...@gmail.com>.
I've done this in the past, and it worked out well. Stored Avro schema
in ZooKeeper with an integer id and prefixed each message with the id.
You have to make sure when you register a new schema that it resolves
with the current version (ResolvingDecoder helps with this).
-David
On 6/13/13 4:07 AM, Shone Sadler wrote:
> Thanks Jun & Phil!
>
> Shone
>
>
> On Thu, Jun 13, 2013 at 12:00 AM, Jun Rao <ju...@gmail.com> wrote:
>
>> Yes, we just have customized encoder that encodes the first 4 bytes of md5
>> of the schema, followed by Avro bytes.
>>
>> Thanks,
>>
>> Jun
>>
>>
>> On Wed, Jun 12, 2013 at 9:50 AM, Shone Sadler <shone.sadler@gmail.com
>>> wrote:
>>> Jun,
>>> I like the idea of an explicit version field, if the schema can be
>> derived
>>> from the topic name itself. The storage (say 1-4 bytes) would require
>> less
>>> overhead than a 128 bit md5 at the added cost of managing the version#.
>>>
>>> Is it correct to assume that your applications are using two schemas
>> then,
>>> one system level schema to deserialize the schema id and bytes for the
>>> application message and a second schema to deserialize those bytes with
>> the
>>> application schema?
>>>
>>> Thanks again!
>>> Shone
>>>
>>>
>>> On Wed, Jun 12, 2013 at 11:31 AM, Jun Rao <ju...@gmail.com> wrote:
>>>
>>>> Actually, currently our schema id is the md5 of the schema itself. Not
>>>> fully sure how this compares with an explicit version field in the
>>> schema.
>>>> Thanks,
>>>>
>>>> Jun
>>>>
>>>>
>>>> On Wed, Jun 12, 2013 at 8:29 AM, Jun Rao <ju...@gmail.com> wrote:
>>>>
>>>>> At LinkedIn, we are using option 2.
>>>>>
>>>>> Thanks,
>>>>>
>>>>> Jun
>>>>>
>>>>>
>>>>> On Wed, Jun 12, 2013 at 7:14 AM, Shone Sadler <
>> shone.sadler@gmail.com
>>>>> wrote:
>>>>>
>>>>>> Hello everyone,
>>>>>>
>>>>>> After doing some searching on the mailing list for best practices on
>>>>>> integrating Avro with Kafka there appears to be at least 3 options
>> for
>>>>>> integrating the Avro Schema; 1) embedding the entire schema within
>> the
>>>>>> message 2) embedding a unique identifier for the schema in the
>> message
>>>> and
>>>>>> 3) deriving the schema from the topic/resource name.
>>>>>>
>>>>>> Option 2, appears to be the best option in terms of both efficiency
>>> and
>>>>>> flexibility. However, from a programming perspective it complicates
>>> the
>>>>>> solution with the need for both an envelope schema (containing a
>>> "schema
>>>>>> id" and "bytes" field for record data) and message schema
>> (containing
>>>> the
>>>>>> application specific message fields). This requires two levels of
>>>>>> serialization/deserialization.
>>>>>> Questions:
>>>>>> 1) How are others dealing with versioning of schemas?
>>>>>> 2) Is there a more elegant means of embedding a schema ids in a Avro
>>>>>> message (I am new to both currently ;-)?
>>>>>>
>>>>>> Thanks in advance!
>>>>>>
>>>>>> Shone
>>>>>>
>>>>>
Re: Versioning Schema's
Posted by Shone Sadler <sh...@gmail.com>.
Thanks Jun & Phil!
Shone
On Thu, Jun 13, 2013 at 12:00 AM, Jun Rao <ju...@gmail.com> wrote:
> Yes, we just have customized encoder that encodes the first 4 bytes of md5
> of the schema, followed by Avro bytes.
>
> Thanks,
>
> Jun
>
>
> On Wed, Jun 12, 2013 at 9:50 AM, Shone Sadler <shone.sadler@gmail.com
> >wrote:
>
> > Jun,
> > I like the idea of an explicit version field, if the schema can be
> derived
> > from the topic name itself. The storage (say 1-4 bytes) would require
> less
> > overhead than a 128 bit md5 at the added cost of managing the version#.
> >
> > Is it correct to assume that your applications are using two schemas
> then,
> > one system level schema to deserialize the schema id and bytes for the
> > application message and a second schema to deserialize those bytes with
> the
> > application schema?
> >
> > Thanks again!
> > Shone
> >
> >
> > On Wed, Jun 12, 2013 at 11:31 AM, Jun Rao <ju...@gmail.com> wrote:
> >
> > > Actually, currently our schema id is the md5 of the schema itself. Not
> > > fully sure how this compares with an explicit version field in the
> > schema.
> > >
> > > Thanks,
> > >
> > > Jun
> > >
> > >
> > > On Wed, Jun 12, 2013 at 8:29 AM, Jun Rao <ju...@gmail.com> wrote:
> > >
> > > > At LinkedIn, we are using option 2.
> > > >
> > > > Thanks,
> > > >
> > > > Jun
> > > >
> > > >
> > > > On Wed, Jun 12, 2013 at 7:14 AM, Shone Sadler <
> shone.sadler@gmail.com
> > > >wrote:
> > > >
> > > >> Hello everyone,
> > > >>
> > > >> After doing some searching on the mailing list for best practices on
> > > >> integrating Avro with Kafka there appears to be at least 3 options
> for
> > > >> integrating the Avro Schema; 1) embedding the entire schema within
> the
> > > >> message 2) embedding a unique identifier for the schema in the
> message
> > > and
> > > >> 3) deriving the schema from the topic/resource name.
> > > >>
> > > >> Option 2, appears to be the best option in terms of both efficiency
> > and
> > > >> flexibility. However, from a programming perspective it complicates
> > the
> > > >> solution with the need for both an envelope schema (containing a
> > "schema
> > > >> id" and "bytes" field for record data) and message schema
> (containing
> > > the
> > > >> application specific message fields). This requires two levels of
> > > >> serialization/deserialization.
> > > >> Questions:
> > > >> 1) How are others dealing with versioning of schemas?
> > > >> 2) Is there a more elegant means of embedding a schema ids in a Avro
> > > >> message (I am new to both currently ;-)?
> > > >>
> > > >> Thanks in advance!
> > > >>
> > > >> Shone
> > > >>
> > > >
> > > >
> > >
> >
>
Re: Versioning Schema's
Posted by Jun Rao <ju...@gmail.com>.
Yes, we just have customized encoder that encodes the first 4 bytes of md5
of the schema, followed by Avro bytes.
Thanks,
Jun
On Wed, Jun 12, 2013 at 9:50 AM, Shone Sadler <sh...@gmail.com>wrote:
> Jun,
> I like the idea of an explicit version field, if the schema can be derived
> from the topic name itself. The storage (say 1-4 bytes) would require less
> overhead than a 128 bit md5 at the added cost of managing the version#.
>
> Is it correct to assume that your applications are using two schemas then,
> one system level schema to deserialize the schema id and bytes for the
> application message and a second schema to deserialize those bytes with the
> application schema?
>
> Thanks again!
> Shone
>
>
> On Wed, Jun 12, 2013 at 11:31 AM, Jun Rao <ju...@gmail.com> wrote:
>
> > Actually, currently our schema id is the md5 of the schema itself. Not
> > fully sure how this compares with an explicit version field in the
> schema.
> >
> > Thanks,
> >
> > Jun
> >
> >
> > On Wed, Jun 12, 2013 at 8:29 AM, Jun Rao <ju...@gmail.com> wrote:
> >
> > > At LinkedIn, we are using option 2.
> > >
> > > Thanks,
> > >
> > > Jun
> > >
> > >
> > > On Wed, Jun 12, 2013 at 7:14 AM, Shone Sadler <shone.sadler@gmail.com
> > >wrote:
> > >
> > >> Hello everyone,
> > >>
> > >> After doing some searching on the mailing list for best practices on
> > >> integrating Avro with Kafka there appears to be at least 3 options for
> > >> integrating the Avro Schema; 1) embedding the entire schema within the
> > >> message 2) embedding a unique identifier for the schema in the message
> > and
> > >> 3) deriving the schema from the topic/resource name.
> > >>
> > >> Option 2, appears to be the best option in terms of both efficiency
> and
> > >> flexibility. However, from a programming perspective it complicates
> the
> > >> solution with the need for both an envelope schema (containing a
> "schema
> > >> id" and "bytes" field for record data) and message schema (containing
> > the
> > >> application specific message fields). This requires two levels of
> > >> serialization/deserialization.
> > >> Questions:
> > >> 1) How are others dealing with versioning of schemas?
> > >> 2) Is there a more elegant means of embedding a schema ids in a Avro
> > >> message (I am new to both currently ;-)?
> > >>
> > >> Thanks in advance!
> > >>
> > >> Shone
> > >>
> > >
> > >
> >
>
Re: Versioning Schema's
Posted by "Hargett, Phil" <ph...@mirror-image.com>.
For one of our key Kafka-based applications, we ensure that all messages in the stream have a common binary format, which includes (among other things) a version identifier and a schema identifier. The version refers to the format itself, and the schema refers to the "payload," which s the data for the application itself.
Because we have a small number of schemas (50-100) and we only introduce 5-10 per year, we stash the mapping from schema identifier to schema details for easy access in ZooKeeper.
This does basically create 2 levels of serialization but most processing we do occurs just by reading the common format, and not deserializing the payload. Only specialized code has to do that extra step.
On Jun 12, 2013, at 12:50 PM, "Shone Sadler" <sh...@gmail.com> wrote:
> Jun,
> I like the idea of an explicit version field, if the schema can be derived
> from the topic name itself. The storage (say 1-4 bytes) would require less
> overhead than a 128 bit md5 at the added cost of managing the version#.
>
> Is it correct to assume that your applications are using two schemas then,
> one system level schema to deserialize the schema id and bytes for the
> application message and a second schema to deserialize those bytes with the
> application schema?
>
> Thanks again!
> Shone
>
>
> On Wed, Jun 12, 2013 at 11:31 AM, Jun Rao <ju...@gmail.com> wrote:
>
>> Actually, currently our schema id is the md5 of the schema itself. Not
>> fully sure how this compares with an explicit version field in the schema.
>>
>> Thanks,
>>
>> Jun
>>
>>
>> On Wed, Jun 12, 2013 at 8:29 AM, Jun Rao <ju...@gmail.com> wrote:
>>
>>> At LinkedIn, we are using option 2.
>>>
>>> Thanks,
>>>
>>> Jun
>>>
>>>
>>> On Wed, Jun 12, 2013 at 7:14 AM, Shone Sadler <shone.sadler@gmail.com
>>> wrote:
>>>
>>>> Hello everyone,
>>>>
>>>> After doing some searching on the mailing list for best practices on
>>>> integrating Avro with Kafka there appears to be at least 3 options for
>>>> integrating the Avro Schema; 1) embedding the entire schema within the
>>>> message 2) embedding a unique identifier for the schema in the message
>> and
>>>> 3) deriving the schema from the topic/resource name.
>>>>
>>>> Option 2, appears to be the best option in terms of both efficiency and
>>>> flexibility. However, from a programming perspective it complicates the
>>>> solution with the need for both an envelope schema (containing a "schema
>>>> id" and "bytes" field for record data) and message schema (containing
>> the
>>>> application specific message fields). This requires two levels of
>>>> serialization/deserialization.
>>>> Questions:
>>>> 1) How are others dealing with versioning of schemas?
>>>> 2) Is there a more elegant means of embedding a schema ids in a Avro
>>>> message (I am new to both currently ;-)?
>>>>
>>>> Thanks in advance!
>>>>
>>>> Shone
>>>>
>>>
>>>
>>
Re: Versioning Schema's
Posted by Shone Sadler <sh...@gmail.com>.
Jun,
I like the idea of an explicit version field, if the schema can be derived
from the topic name itself. The storage (say 1-4 bytes) would require less
overhead than a 128 bit md5 at the added cost of managing the version#.
Is it correct to assume that your applications are using two schemas then,
one system level schema to deserialize the schema id and bytes for the
application message and a second schema to deserialize those bytes with the
application schema?
Thanks again!
Shone
On Wed, Jun 12, 2013 at 11:31 AM, Jun Rao <ju...@gmail.com> wrote:
> Actually, currently our schema id is the md5 of the schema itself. Not
> fully sure how this compares with an explicit version field in the schema.
>
> Thanks,
>
> Jun
>
>
> On Wed, Jun 12, 2013 at 8:29 AM, Jun Rao <ju...@gmail.com> wrote:
>
> > At LinkedIn, we are using option 2.
> >
> > Thanks,
> >
> > Jun
> >
> >
> > On Wed, Jun 12, 2013 at 7:14 AM, Shone Sadler <shone.sadler@gmail.com
> >wrote:
> >
> >> Hello everyone,
> >>
> >> After doing some searching on the mailing list for best practices on
> >> integrating Avro with Kafka there appears to be at least 3 options for
> >> integrating the Avro Schema; 1) embedding the entire schema within the
> >> message 2) embedding a unique identifier for the schema in the message
> and
> >> 3) deriving the schema from the topic/resource name.
> >>
> >> Option 2, appears to be the best option in terms of both efficiency and
> >> flexibility. However, from a programming perspective it complicates the
> >> solution with the need for both an envelope schema (containing a "schema
> >> id" and "bytes" field for record data) and message schema (containing
> the
> >> application specific message fields). This requires two levels of
> >> serialization/deserialization.
> >> Questions:
> >> 1) How are others dealing with versioning of schemas?
> >> 2) Is there a more elegant means of embedding a schema ids in a Avro
> >> message (I am new to both currently ;-)?
> >>
> >> Thanks in advance!
> >>
> >> Shone
> >>
> >
> >
>
Re: Versioning Schema's
Posted by Jun Rao <ju...@gmail.com>.
Actually, currently our schema id is the md5 of the schema itself. Not
fully sure how this compares with an explicit version field in the schema.
Thanks,
Jun
On Wed, Jun 12, 2013 at 8:29 AM, Jun Rao <ju...@gmail.com> wrote:
> At LinkedIn, we are using option 2.
>
> Thanks,
>
> Jun
>
>
> On Wed, Jun 12, 2013 at 7:14 AM, Shone Sadler <sh...@gmail.com>wrote:
>
>> Hello everyone,
>>
>> After doing some searching on the mailing list for best practices on
>> integrating Avro with Kafka there appears to be at least 3 options for
>> integrating the Avro Schema; 1) embedding the entire schema within the
>> message 2) embedding a unique identifier for the schema in the message and
>> 3) deriving the schema from the topic/resource name.
>>
>> Option 2, appears to be the best option in terms of both efficiency and
>> flexibility. However, from a programming perspective it complicates the
>> solution with the need for both an envelope schema (containing a "schema
>> id" and "bytes" field for record data) and message schema (containing the
>> application specific message fields). This requires two levels of
>> serialization/deserialization.
>> Questions:
>> 1) How are others dealing with versioning of schemas?
>> 2) Is there a more elegant means of embedding a schema ids in a Avro
>> message (I am new to both currently ;-)?
>>
>> Thanks in advance!
>>
>> Shone
>>
>
>
Re: Versioning Schema's
Posted by Jun Rao <ju...@gmail.com>.
At LinkedIn, we are using option 2.
Thanks,
Jun
On Wed, Jun 12, 2013 at 7:14 AM, Shone Sadler <sh...@gmail.com>wrote:
> Hello everyone,
>
> After doing some searching on the mailing list for best practices on
> integrating Avro with Kafka there appears to be at least 3 options for
> integrating the Avro Schema; 1) embedding the entire schema within the
> message 2) embedding a unique identifier for the schema in the message and
> 3) deriving the schema from the topic/resource name.
>
> Option 2, appears to be the best option in terms of both efficiency and
> flexibility. However, from a programming perspective it complicates the
> solution with the need for both an envelope schema (containing a "schema
> id" and "bytes" field for record data) and message schema (containing the
> application specific message fields). This requires two levels of
> serialization/deserialization.
> Questions:
> 1) How are others dealing with versioning of schemas?
> 2) Is there a more elegant means of embedding a schema ids in a Avro
> message (I am new to both currently ;-)?
>
> Thanks in advance!
>
> Shone
>