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Questions tagged [ksqldb]

ksqlDB: an event streaming database for Apache Kafka.

ksqlDB is a source-available event streaming database for Apache Kafka® developed by Confluent. It is distributed, scalable, reliable, and real-time. ksqlDB combines the power of real-time stream processing with the approachable feel of a relational database through a familiar, lightweight SQL syntax.

You can download ksqlDB at https://github.com/confluentinc/ksql

There is a quickstart at: https://ksqldb.io/quickstart.html

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KSQL query and tables storage

I was looking for a documentation about where KSQL storage querys and tables. For example, since KSQL was built to work with Kafka, when I create a table from a topic, or when I write a query, where are stored the tables or the query results? More…
Maurizio Cimino
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KSQL Table-Table Left outer Join emit same join result more than once

using KSQL, and performing left outer join, i can see the result of my join sometime emitted more than once. In other words, the same join result is emitted more than once. I am not talking about, a version of the join with the null value on the…
MaatDeamon
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Does KSQL support Kafka stream Processing Guarantees?

I wonder if KSQL support https://docs.confluent.io/current/streams/concepts.html#processing-guarantees Exactly_once semantic ?
MaatDeamon
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KSQL and lookup Table akka GlobalKtable akka broadcast Join?

Does KSQL support GlobalKtable join with Ktable ? I could not find anything like that at this point. If not is there any known workaround ?
MaatDeamon
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KSQL Server Elastic Scaling in Kubernetes

in the context of kubernetes or else, does it make sense to have one KSQL SERVER per application? When i read the capacity planning for KSQL Server, it is seems the basic settings are for running multiple queries on one server. However I feel like…
MaatDeamon
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KSQL Query number of Thread

is there a way to specify the number of Threads that a KSQL query running on a KSQL Server should consume ? Is other words the parallelism of the query. Is there any limit to the number of application that can be run on a KSQL Server ? When or how…
MaatDeamon
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Kafka Stream Ksql Json

Does kafka stream / Ksql actually support json natively somehow? What are the other formats supported ? I have seen that is it possible to have flat json interpreted as table. I want to understand that part a bit better; what are the other formats…
MaatDeamon
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Kafka-Connect JDBC Connector tinyint to boolean mapping

I have a Kafka-Connect job configured to query a MySQL table periodically and place messages on a queue. The structure of these messages are defined using an Avro schema. I am having an issue with the mapping for one of my columns. The column is…
Paddyd
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KSQL is failing with CharConversionException: Invalid UTF-32 character when reading stream

I'm streaming some data into Kafka using Kafka Connect. I'm able to view this data using print 'kdc-01-orders' from beginning;. The data looks to be correct JSON. Just to make sure, I parsed it as JSON successfully. So I created a table using that…
user377628
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How to set group.id in KSQL application

I need to set a 'group.id' property in my KSQL application. I know that is possible in Kafka Stream application by 'application.id' property, but it dosn't work for KSQL.
Marco Catalano
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KSQL 'SELECT *' query takes 10 seconds before it starts returning any results

I have a ksql table with less than 1000 records in it. When I run this query select * from table_name it takes up to 10 seconds before the query starts to return any data. The machine running Kafka, zookeeper, ksql and schema registry is not…
mungujn
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Insert Data to MongoDB with Kafka-MongoDB-Connect

I'm trying to insert data from a Kafka topic to a MongoDB database with Kafka-MongoDB-Connect. The Kafka Connect properties…
wahib
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What is java/scala kafka streams equivalent for KSQL join WHERE clause?

Let's say I have 2 kafka streams (kafka-streams-scala library, version 2.2.0): val builder: StreamsBuilder = new StreamsBuilder val stream1: KStream[String, GenericRecord] = builder.stream[String, GenericRecord]("topic1") val stream2:…
Andrii Black
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Duplicate data in ksql table | How to update the rows of ksql table on same ROWKEY update?

I've created a table in ksql from kafka topic. Pushed a set of data to topic and table's populated. Posted a query and got the response too. For the 2nd time I've pushed the same data into the topic and the table gets loaded again. Now, when I…
srikanth
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Why do I see duplicates in KSQL stream?

I created ksql stream using create stream as select, and for some reason, stream's CSAS persistent streaming query produces 4 duplicate records, for each source record. How can I avoid duplicates? What is wrong with my setup? Here is my setup: A…
andrii
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