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Status

Current state:   [One of "Under Discussion", "Accepted", "Rejected"]

Discussion thread: here [Change the link from the KIP proposal email archive to your own email thread]

JIRA: here [Change the link from KAFKA-1 to your own ticket]13511 

Please keep the discussion on the mailing list rather than commenting on the wiki (wiki discussions get unwieldy fast).

Motivation

Describe the problems you are trying to solve.

Public Interfaces

Briefly list any new interfaces that will be introduced as part of this proposal or any existing interfaces that will be removed or changed. The purpose of this section is to concisely call out the public contract that will come along with this feature.

A public interface is any change to the following:

• Binary log format

• The network protocol and api behavior

• Any class in the public packages under clientsConfiguration, especially client configuration

  • org/apache/kafka/common/serialization

  • org/apache/kafka/common

  • org/apache/kafka/common/errors

  • org/apache/kafka/clients/producer

  • org/apache/kafka/clients/consumer (eventually, once stable)

• Monitoring

• Command line tools and arguments

• Anything else that will likely break existing users in some way when they upgrade

Proposed Changes

TimestampConverter should have a config to define which precision to use when convert from and to Long epoch timestamps.

Currently, the Kafka Connect SMT TimestampConverter can convert Timestamp from multiples sources types (String, Long or Date) into different target types (String, Long or Date).

The problem is that Long as a source or as a target type is required to be epoch in milliseconds.

In many cases, epoch is represented with different precisions within external systems : seconds, milliseconds, microseconds, nanoseconds

This issue was raised several times : 

• KAFKA-12364
• KAFKA-10561

Public Interfaces

Add a config property epoch.precision, defaultmillis for compatibility.

Proposed Changes

New config property for TimestampConverter

"transforms.TimestampConverter.type": "org.apache.kafka.connect.transforms.TimestampConverter$Value",
"transforms.TimestampConverter.field": "event_date_long",
"transforms.TimestampConverter.epoch.precision": "micros",
"transforms.TimestampConverter.target.type": "Timestamp"

int32 and seconds

Since int32 should not be used for timestamp, obsolete systems that produces int32 into Kafka and want should willingly chain Cast SMT and then TimestampConverter SMT if they want to use this feature.

"transforms": "Cast,TimestampConverter",
"transforms.Cast.type": "org.apache.kafka.connect.transforms.Cast$Value",
"transforms.Cast.spec": "event_date_int:int64",
"transforms.TimestampConverter.type": "org.apache.kafka.connect.transforms.TimestampConverter$Value",
"transforms.TimestampConverter.field": "event_date_int",
"transforms.TimestampConverter.epoch.precision": "seconds",
"transforms.TimestampConverter.target.type": "Timestamp"

java.util.Date and SimpleDateFormat limitations

Since these classes can only handle precisions down to the millisecond, it should be stated that:

• converting Long microseconds into any target type leads to a precision loss (truncation after millis)
• converting any source type into Long microseconds, the microseconds part will always be 000

This raises an interesting question (out of the scope of this KIP I guess) regarding the future of java.util.DateDescribe the new thing you want to do in appropriate detail. This may be fairly extensive and have large subsections of its own. Or it may be a few sentences. Use judgement based on the scope of the change.

Compatibility, Deprecation, and Migration Plan

...

The change will not break the compatibility.

Rejected Alternatives

If there are alternative ways of accomplishing the same thing, what were they? The purpose of this section is to motivate why the design is the way it is and not some other way.