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TiSpark

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TiSpark is a thin layer built for running Apache Spark on top of TiDB/TiKV to answer the complex OLAP queries. It takes advantages of both the Spark platform and the distributed TiKV cluster, at the same time, seamlessly glues to TiDB, the distributed OLTP database, to provide a Hybrid Transactional/Analytical Processing (HTAP) to serve as a one-stop solution for online transactions and analysis.

Getting TiSpark

The current stable version is 1.0.

If you are using maven, add the following to your pom.xml:

<dependency>
  <groupId>com.pingcap.tispark</groupId>
  <artifactId>tispark-core</artifactId>
  <version>1.0</version>
</dependency>

If you're using SBT, add the following line to your build file:

libraryDependencies += "com.pingcap.tispark" % "tispark-core" % "1.0"

For other build tools, you can visit search.maven.org and search with GroupId Maven Search(This search will also list all available modules of TiSpark including tikv-client).

TiSpark Architecture

architecture

  • TiSpark integrates with Spark Catalyst Engine deeply. It provides precise control of the computing, which allows Spark read data from TiKV efficiently. It also supports index seek, which improves the performance of the point query execution significantly.

  • It utilizes several strategies to push down the computing to reduce the size of dataset handling by Spark SQL, which accelerates the query execution. It also uses the TiDB built-in statistical information for the query plan optimization.

  • From the data integration point of view, TiSpark + TiDB provides a solution runs both transaction and analysis directly on the same platform without building and maintaining any ETLs. It simplifies the system architecture and reduces the cost of maintenance.

  • In addition, you can deploy and utilize tools from the Spark ecosystem for further data processing and manipulation on TiDB. For example, using TiSpark for data analysis and ETL; retrieving data from TiKV as a machine learning data source; generating reports from the scheduling system and so on.

TiSpark depends on the existence of TiKV clusters and PDs. It also needs to setup and use Spark clustering platform.

A thin layer of TiSpark. Most of the logic is inside tikv-client library. https://github.com/pingcap/tispark/tree/master/tikv-client

Quick Start

From Spark-shell:

./bin/spark-shell --jars /wherever-it-is/tispark-${version}-jar-with-dependencies.jar
import org.apache.spark.sql.TiContext
val ti = new TiContext(spark) 

// Map all TiDB tables from database tpch as Spark SQL tables
ti.tidbMapDatabase("tpch")

spark.sql("select count(*) from lineitem").show

Metadata loading

If you are using spark-shell, you need to manually load schema information as decribed above.

If you have too many tables, you might choose to disable histogram preparison and loading will be faster.

ti.tidbMapDatabase("tpch", autoLoadStatistics = true)

If you have two tables with same name in different databases, you might choose to append database name as prefix for table name:

ti.tidbMapDatabase("tpch", dbNameAsPrefix = true)

If you have too many tables and use only some of them, to speed up meta loading process, you might manually load only tables you use:

ti.tidbTable("tpch", "lineitem")

If you have newly created table which is not yet synchronized into TiSpark between refresh period, you can manually refresh schema metadata:

ti.meta.reloadMeta

Current Version

ti.version

or

spark.sql("select ti_version()").show

Configuration

Below configurations can be put together with spark-defaults.conf or passed in the same way as other Spark config properties.

Key Default Value Description
spark.tispark.pd.addresses 127.0.0.1:2379 PD Cluster Addresses, split by comma
spark.tispark.grpc.framesize 268435456 Max frame size of GRPC response
spark.tispark.grpc.timeout_in_sec 10 GRPC timeout time in seconds
spark.tispark.meta.reload_period_in_sec 60 Metastore reload period in seconds
spark.tispark.plan.allow_agg_pushdown true If allow aggregation pushdown (in case of busy TiKV nodes)
spark.tispark.plan.allow_index_read false If allow index read (which might cause heavy pressure on TiKV)
spark.tispark.index.scan_batch_size 20000 How many row key in batch for concurrent index scan
spark.tispark.index.scan_concurrency 5 Maximal threads for index scan retrieving row keys (shared among tasks inside each JVM)
spark.tispark.table.scan_concurrency 512 Maximal threads for table scan (shared among tasks inside each JVM)
spark.tispark.request.command.priority "Low" "Low", "Normal", "High" which impacts resource to get in TiKV. Low is recommended for not disturbing OLTP workload
spark.tispark.coprocess.streaming false Whether to use streaming for response fetching
spark.tispark.plan.unsupported_pushdown_exprs "" A comma separated list of expressions. In case you have very old version of TiKV, you might disable some of the expression push-down if not supported
spark.tispark.plan.downgrade.index_threshold 10000 If index scan ranges on one region exceeds this limit in original request, downgrade this region's request to table scan rather than original planned index scan
spark.tispark.type.unsupported_mysql_types "time,enum,set,year,json" A comma separated list of mysql types TiSpark does not support currently, refer to Unsupported MySQL Type List below
spark.tispark.request.timezone.offset Local Timezone offset An integer, represents timezone offset to UTC time(like 28800, GMT+8), this value will be added to requests issued to TiKV
spark.tispark.show_rowid Show implicit row Id If to show implicit row Id if exists

Unsupported MySQL Type List

Mysql Type
time
enum
set
year
json

Statistics information

If you want to know how TiSpark could benefit from TiDB's statistic information, read more here.

Quick start

Read the Quick Start.

How to build

To build all TiSpark modules :

mvn clean install -Dmaven.test.skip=true

Remember to add -Dmaven.test.skip=true to skip all the tests if you don't need to run them.

How to test

We use docker-compose to provide tidb cluster service which allows you to run test across different platforms. It is recommended to install docker in order to test locally, or you can set up your own TiDB cluster locally as you wish.

If you prefer the docker way, you can use docker-compose up -d to launch tidb cluster service under tispark home directory. If you want to see tidb cluster's log you can launch via docker-compose up. You can use docker-compose down to shutdown entire tidb cluster service. All data is stored in data directory at the root of this project. Feel free to change it.

You can read more about test here.

Follow us

Twitter

@PingCAP

Mailing list

[email protected]

Google Group

License

TiSpark is under the Apache 2.0 license. See the LICENSE file for details.

Latest Releases
TiSpark 1.0 GA
 Apr. 26 2018
1.0-RC2
 Apr. 25 2018
1.0-RC1
 Mar. 15 2018
1.0-RC1
 Mar. 8 2018
pre-exp-refactor
 Jan. 16 2018