Kafka consumer, is there a way to filter out messages using key only?

[Hao Sun]

Hi, I am using 1.7 on K8S.

I have a huge amount of data in kafka, but I only need a tiny portion of it.

It is a keyed stream, the value in JSON encoded. I want to avoid deserialization of the value, since it is very expensive. Can I only filter based on the key?

I know there is a KeyedDeserializationSchema, but can I use it to filter data?

[Dawid Wysakowicz-2]

Hi,

I'm afraid that there is no out-of-the box solution for this, but what you could do is to generate from KeyedDeserializationSchema some marker (Optional, null value...) based on the message key, that would allow you later to filter it out. So assuming the Optional solution the result of KeyedDeserializationSchema#deserialize could be Optional.empty() for invalid keys and Optional.of(deserializedValue) for valid keys.

Best,

Dawid

On 18/12/2018 20:22, Hao Sun wrote:

Hi, I am using 1.7 on K8S.

I have a huge amount of data in kafka, but I only need a tiny portion of it.

It is a keyed stream, the value in JSON encoded. I want to avoid deserialization of the value, since it is very expensive. Can I only filter based on the key?

I know there is a KeyedDeserializationSchema, but can I use it to filter data?

[Dominik Wosiński]

Hey, 
AFAIK, returning null from deserialize function in FlinkKafkaConsumer will indeed filter the message out and it won't be further processed. 

Best Regards,

Dom.

śr., 19 gru 2018 o 11:06 Dawid Wysakowicz <[hidden email]> napisał(a):

Hi,

I'm afraid that there is no out-of-the box solution for this, but what you could do is to generate from KeyedDeserializationSchema some marker (Optional, null value...) based on the message key, that would allow you later to filter it out. So assuming the Optional solution the result of KeyedDeserializationSchema#deserialize could be Optional.empty() for invalid keys and Optional.of(deserializedValue) for valid keys.

Best,

Dawid

On 18/12/2018 20:22, Hao Sun wrote:

Hi, I am using 1.7 on K8S.

I have a huge amount of data in kafka, but I only need a tiny portion of it.

It is a keyed stream, the value in JSON encoded. I want to avoid deserialization of the value, since it is very expensive. Can I only filter based on the key?

I know there is a KeyedDeserializationSchema, but can I use it to filter data?

[Hao Sun]

Cool, thanks! I used the option value approach, worked well.

On Thu, Dec 27, 2018, 03:49 Dominik Wosiński <[hidden email]> wrote:

Hey, 
AFAIK, returning null from deserialize function in FlinkKafkaConsumer will indeed filter the message out and it won't be further processed.

Best Regards,

Dom.

śr., 19 gru 2018 o 11:06 Dawid Wysakowicz <[hidden email]> napisał(a):

Hi,

I'm afraid that there is no out-of-the box solution for this, but what you could do is to generate from KeyedDeserializationSchema some marker (Optional, null value...) based on the message key, that would allow you later to filter it out. So assuming the Optional solution the result of KeyedDeserializationSchema#deserialize could be Optional.empty() for invalid keys and Optional.of(deserializedValue) for valid keys.

Best,

Dawid

On 18/12/2018 20:22, Hao Sun wrote:

Hi, I am using 1.7 on K8S.

I have a huge amount of data in kafka, but I only need a tiny portion of it.

It is a keyed stream, the value in JSON encoded. I want to avoid deserialization of the value, since it is very expensive. Can I only filter based on the key?

I know there is a KeyedDeserializationSchema, but can I use it to filter data?