One Does Not Simply Query a Stream

One Does Not Simply Query a Stream! Viktor Gamov, Confluent @gamussa @gamussa | @confluentinc | Athens Apache Kafka® Meetup November 5th, 2025 @apacheiceberg

@gamussa | @confluentinc | @apacheiceberg

Viktor GAMOV Principal Developer Advocate | Confluent Kafka in Action, Co-author THE CLOUD CONNECTIVITY COMPANY X and Bluesky: @gamussa Kong Confidential

Simpler times Monolith @gamussa || @confluentinc gamov.dev/rel | | @apacheiceberg @ConfluentInc @gamussa

Simpler analytics ETL and CDC @gamussa || @confluentinc gamov.dev/rel | | @apacheiceberg @ConfluentInc @gamussa

Data Pipelines Streaming data pipelines and Microservices @gamussa | gamov.dev/rel | @ConfluentInc

LOG @gamussa || @confluentinc gamov.dev/rel | | @apacheiceberg @ConfluentInc @gamussa

OLTP stream vs OLAP vs. OLTP in Streams OLAP streams @gamussa || @confluentinc gamov.dev/rel | | @apacheiceberg @ConfluentInc @gamussa

` • Connect/Relational DB • Kafka Streams • Streaming SQL • Real-Time OLAP • Data Warehouse/ Data Lake • Tableflow @gamussa | @confluentinc | @apacheiceberg

Kafka Connect @gamussa | @confluentinc | @apacheiceberg

` Connect/RDBMS • Suitable for smaller data • Transactional • Familiar to users @gamussa | @confluentinc | @apacheiceberg

Connect/RDBMS Broker Broker Broker Cluster Data Source Kafka Connect Kafka Connect @gamussa | @confluentinc | @apacheiceberg Data Sink

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Kafka Streams @gamussa | @confluentinc | @apacheiceberg

Kafka Streams (transactional) • Ingests directly from a topic • KTable • Forms an in-memory key/value store suitable for querying by topic key • Scalable across members of a consumer group • Readable through Interactive Queries @gamussa | @confluentinc | @apacheiceberg

Kafka Streams (analytical) • Full-featured Java stream processing API • Arbitrary streaming computation • Can emit new streams (not this talk) • KTables queryable by key • Every read pattern requires its own topology • Interactive Queries again @gamussa | @confluentinc | @apacheiceberg

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Streaming SQLs @gamussa | @confluentinc | @apacheiceberg

Streaming Database • SQL for Queries • Streaming Source is 1st class citizen • Persistence / Storage @gamussa | @confluentinc | @apacheiceberg

Streaming SQL • ksqlDB • RisingWave • Materialize • TimePlus @gamussa | @confluentinc | @apacheiceberg

But Viktor, Flink has SQL Why not Flink? @gamussa || @confluentinc gamov.dev/rel | | @apacheiceberg @ConfluentInc @gamussa

@gamussa || @confluentinc gamov.dev/rel | | @apacheiceberg @ConfluentInc @gamussa

ksqlDB • «Streaming Database» • Provides persistent TABLE abstraction • Pull and Push queries • Like Kafka Streams, but in SQL @gamussa | @confluentinc | @apacheiceberg

Materialize • Replacement data warehouse • Integrates with Kafka, Postgres, dbt • The Materialized View is the central abstraction • Views are persistent and queryable • Postgres wire-compatible • Positioned as an analytics solution @gamussa | @confluentinc | @apacheiceberg

Rising Wave • Distributed SQL Streaming database • Cloud and OSS versions • Implementation of Flink in Rust • Kafka, Pulsar, Kinesis integrations • Flink+persistent views • Postgres wire-compatible @gamussa | @confluentinc | @apacheiceberg

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Real-Time Analytics Database

Real-Time OLAP • Designed for high concurrency, low latency queries • Ingests from streaming and batch sources • Intimate integration with Kafka • Conventional tables and SQL @gamussa | @confluentinc | @apacheiceberg

Real-Time OLAP • Analytics shaped like real-time data • Analytics when users are decision makers @gamussa | @confluentinc | @apacheiceberg

Cloud Data Warehouses

Cloud Data Warehouses

Cloud Data Warehouses • The cloud-based heir of legacy DWH • Ingest from batch and streaming sources • Biased towards structured data and batch access

Data Lake @gamussa | @confluentinc | @apacheiceberg

Data Lake Anything else We’ll figure this out @gamussa | @confluentinc | @apacheiceberg

Data Lakes • Storage and compute are radically decoupled • Structure is relatively less important • Reads are slow • Streaming is historically difficult @gamussa | @confluentinc | @apacheiceberg

Data Lakes • Started as the HDFS cluster • Became S3 • That didn’t help… • ELT vs. ETL • Iceberg/Hudi/DeltaLake @gamussa | @confluentinc | @apacheiceberg

Iceberg @gamussa | @confluentinc | @apacheiceberg

Tableflow @gamussa | @confluentinc | @apacheiceberg

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@gamussa | @confluentinc | @apacheiceberg

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No Solutions Technology Selection only Trade Offs @gamussa || @confluentinc gamov.dev/rel | | @apacheiceberg @ConfluentInc @gamussa

Sometimes you go with what you know @gamussa | @confluentinc | @apacheiceberg

This is not bad! @gamussa | @confluentinc | @apacheiceberg

Performance Performance @gamussa | @confluentinc | @apacheiceberg

Community/Adoption Community @gamussa | @confluentinc | @apacheiceberg

Differentiated Application Code Area of Exploration Kafka @gamussa || @confluentinc gamov.dev/rel | | @apacheiceberg @ConfluentInc @gamussa

This is not bad! @gamussa | @confluentinc | @apacheiceberg