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## What changes were proposed in this pull request? This PR adds a new project ` external/kafka-0-10-sql` for Structured Streaming Kafka source. It's based on the design doc: https://docs.google.com/document/d/19t2rWe51x7tq2e5AOfrsM9qb8_m7BRuv9fel9i0PqR8/edit?usp=sharing tdas did most of work and part of them was inspired by koeninger's work. ### Introduction The Kafka source is a structured streaming data source to poll data from Kafka. The schema of reading data is as follows: Column | Type ---- | ---- key | binary value | binary topic | string partition | int offset | long timestamp | long timestampType | int The source can deal with deleting topics. However, the user should make sure there is no Spark job processing the data when deleting a topic. ### Configuration The user can use `DataStreamReader.option` to set the following configurations. Kafka Source's options | value | default | meaning ------ | ------- | ------ | ----- startingOffset | ["earliest", "latest"] | "latest" | The start point when a query is started, either "earliest" which is from the earliest offset, or "latest" which is just from the latest offset. Note: This only applies when a new Streaming query is started, and that resuming will always pick up from where the query left off. failOnDataLost | [true, false] | true | Whether to fail the query when it's possible that data is lost (e.g., topics are deleted, or offsets are out of range). This may be a false alarm. You can disable it when it doesn't work as you expected. subscribe | A comma-separated list of topics | (none) | The topic list to subscribe. Only one of "subscribe" and "subscribeParttern" options can be specified for Kafka source. subscribePattern | Java regex string | (none) | The pattern used to subscribe the topic. Only one of "subscribe" and "subscribeParttern" options can be specified for Kafka source. kafka.consumer.poll.timeoutMs | long | 512 | The timeout in milliseconds to poll data from Kafka in executors fetchOffset.numRetries | int | 3 | Number of times to retry before giving up fatch Kafka latest offsets. fetchOffset.retryIntervalMs | long | 10 | milliseconds to wait before retrying to fetch Kafka offsets Kafka's own configurations can be set via `DataStreamReader.option` with `kafka.` prefix, e.g, `stream.option("kafka.bootstrap.servers", "host:port")` ### Usage * Subscribe to 1 topic ```Scala spark .readStream .format("kafka") .option("kafka.bootstrap.servers", "host:port") .option("subscribe", "topic1") .load() ``` * Subscribe to multiple topics ```Scala spark .readStream .format("kafka") .option("kafka.bootstrap.servers", "host:port") .option("subscribe", "topic1,topic2") .load() ``` * Subscribe to a pattern ```Scala spark .readStream .format("kafka") .option("kafka.bootstrap.servers", "host:port") .option("subscribePattern", "topic.*") .load() ``` ## How was this patch tested? The new unit tests. Author: Shixiong Zhu <shixiong@databricks.com> Author: Tathagata Das <tathagata.das1565@gmail.com> Author: Shixiong Zhu <zsxwing@gmail.com> Author: cody koeninger <cody@koeninger.org> Closes #15102 from zsxwing/kafka-source. |
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Spark SQL
This module provides support for executing relational queries expressed in either SQL or the DataFrame/Dataset API.
Spark SQL is broken up into four subprojects:
- Catalyst (sql/catalyst) - An implementation-agnostic framework for manipulating trees of relational operators and expressions.
- Execution (sql/core) - A query planner / execution engine for translating Catalyst's logical query plans into Spark RDDs. This component also includes a new public interface, SQLContext, that allows users to execute SQL or LINQ statements against existing RDDs and Parquet files.
- Hive Support (sql/hive) - Includes an extension of SQLContext called HiveContext that allows users to write queries using a subset of HiveQL and access data from a Hive Metastore using Hive SerDes. There are also wrappers that allows users to run queries that include Hive UDFs, UDAFs, and UDTFs.
- HiveServer and CLI support (sql/hive-thriftserver) - Includes support for the SQL CLI (bin/spark-sql) and a HiveServer2 (for JDBC/ODBC) compatible server.