0xqq / spark-druid-connector

A library for querying Druid data sources with Apache Spark

spark-druid-connector

A library for querying Druid data sources with Apache Spark.

Compatability

This libaray is compatable with Spark-2.x and Druid-0.9.0+

Usage

Compile

sbt clean assembly

Using with spark-shell

bin/spark-shell --jars spark-druid-connector-assembly-0.1.0-SNAPSHOT.jar

In spark-shell, a temp table could be created like this:

val df = spark.read.format("org.rzlabs.druid").
  option("druidDatasource", "ds1").
  option("zkHost": "localhost:2181").
  option("hyperUniqueColumnInfo", """[{"column":"city", "hllMetric": "unique_city"}]""").load
df.createOrReplaceTempView("ds")
spark.sql("select time, sum(event) from ds group by time").show

or you can create a hive table:

spark.sql("""
  create table ds1 using org.rzlabs.druid options (
    druidDatasource "ds1",
    zkHost "localhost:2181",
    hyperUniqueColumnInfo, "[{\"column\": \"city\", \"hllMetric\": \"unique_city\"}]"
  )
""")

Options

option	required	default value	descrption
druidDatasource	yes	none	data source name in Druid
zkHost	no	localhost	zookeeper server Druid use, e.g., localhost:2181
zkSessionTimeout	no	30000	zk server connection timeout
zkEnableCompression	no	true	zk enbale compression or not
zkDruidPath	no	/druid	The druid metadata root path in zk
zkQualifyDiscoveryNames	no	true
queryGranularity	no	all	The query granularity of the Druid datasource
maxConnectionsPerRoute	no	20	The max simultaneous live connections per Druid server
maxConnections	no	100	The max simultaneous live connnections of the Druid cluster
loadMetadataFromAllSegments	no	true	Fetch metadata from all available segments or not
debugTransformations	no	false	Log debug informations about the transformations or not
timeZoneId	no	UTC
useV2GroupByEngine	no	false	Use V2 groupby engine or not
useSmile	no	true	Use smile binary format as the data format exchanged between client and Druid servers

Major features

Currently

• Direct table creating in Spark without requiring of base table.
• Support Aggregate and Project & Filter operators pushing down and transform to GROUPBY and SCAN query against Druid accordingly.
• Support majority of primitive filter specs, aggregation specs and extraction functions.
• Lightweight datasource metadata updating.

In the future

• Support Join operator.
• Support Limit and Having operators pushing down.
• Suport more primitive specs and extraction functions.
• Support more Druid query specs according to query details.
• Suport datasource creating and metadata lookup.
• ...