Michael, I think you’re right to call this out. I frequently find myself stringing together flows with ExecuteScripts (which you should be able to use to pull a schema out by creating an Avro DataFileStream from the InputStream and then calling getSchema().toString()) or conversions to/from JSON and Avro to handle all the scenarios.
I think the heart of the solution shouldn’t just be the addition of an output attribute including the schema, but something generic like you mention in your (4), especially considering that there are at least 7 issues [1-7] open for variations on this. Instead of a just a converter processor, though, it’d probably be smart to make it some kind of controller service so it can be easily exposed to other processors like ExecuteSQL and QueryDatabaseTable. -joey 1. https://issues.apache.org/jira/browse/NIFI-2743 2. https://issues.apache.org/jira/browse/NIFI-1623 3. https://issues.apache.org/jira/browse/NIFI-1623 4. https://issues.apache.org/jira/browse/NIFI-1702 5. https://issues.apache.org/jira/browse/NIFI-1704 6. https://issues.apache.org/jira/browse/NIFI-1398 7. https://issues.apache.org/jira/browse/NIFI-2725 > On Dec 28, 2016, at 3:18 PM, Knapp, Michael <[email protected]> > wrote: > > Nifi Devs, > > I noticed you have two processors (ExecuteSQL and QueryDatabaseTable) that > perform SQL select statements and put the results into a flow file. While I > am not sure what their difference is, I did notice that they both produce > avro, and the schema is inferred from the result set. While the schema is > included in the output file’s contents, I am not sure of any easy way to get > that from a *StreamCallback. So I am wondering, > > > 1. Could we update the processor to support multiple output formats? I > think CSV should definitely be supported. Parquet might also be useful for > me. JSON is an option but since you already have a ConvertAvroToJSON > processor that is not a big deal for me. > > 2. Could we update the processor to include the schema as one of the > output flow file attributes? > > 3. Is there any utility to get an avro schema from the input stream > callback? > > 4. Has anybody thought about writing a processor to convert Avro to > CSV? Or even something more generic than that, a generic format conversion > processor? It could support CSV, JSON, Avro, Parquet, XML, and possibly > others. > > Please let me know, > > Michael Knapp > Capital One > ________________________________________________________ > > The information contained in this e-mail is confidential and/or proprietary > to Capital One and/or its affiliates and may only be used solely in > performance of work or services for Capital One. The information transmitted > herewith is intended only for use by the individual or entity to which it is > addressed. If the reader of this message is not the intended recipient, you > are hereby notified that any review, retransmission, dissemination, > distribution, copying or other use of, or taking of any action in reliance > upon this information is strictly prohibited. If you have received this > communication in error, please contact the sender and delete the material > from your computer.
