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README.md

TiSpark

Maven Central Javadocs codecov.io License

TiSpark is a thin layer built for running Apache Spark on top of TiDB/TiKV to answer complex OLAP queries. It enjoys the merits of both the Spark platform and the distributed clusters of TiKV while seamlessly integrated to TiDB, a distributed OLTP database, to provide one-stop Hybrid Transactional/Analytical Processing (HTAP) solutions for online transactions and analyses.

Quick start

Read the Quick Start.

Getting TiSpark

  • Currently, TiSpark 2.3.13 is the latest stable version, which is highly recommended. It is compatible with Spark 2.3.0+ and Spark 2.4.0+. It is also compatible with TiDB-2.x、TiDB-3.x and TiDB-4.x. Please follow the document.

  • TiSpark 1.2.1 is the latest stable version compatible with Spark 2.1.0+.

You might also build from sources to try the new features on TiSpark master branch.

If you are using maven (recommended), add the following code to your pom.xml:

<dependencies>
    <dependency>
      <groupId>com.pingcap.tispark</groupId>
      <artifactId>tispark-assembly</artifactId>
      <version>2.3.13</version>
    </dependency>
</dependencies>

If you want to use TiSpark-2.1.x, please use the following configuration:

<dependencies>
    <dependency>
      <groupId>com.pingcap.tispark</groupId>
      <artifactId>tispark-core</artifactId>
      <version>2.1.9-spark_${spark.version}</version>
    </dependency>
</dependencies>

For other build tools, visit https://search.maven.org/ and search with GroupId Maven Search. This search also lists all the available modules of TiSpark including tikv-client.

How to build from sources

TiSpark now supports Spark 2.3.0+、2.4.0+ and 3.0.0+. The earlier TiSpark versions for Spark 2.1.0+ only contain bug-fixes. After these versions, you can still get support for Spark 2.1 until TiSpark 1.2.1.

Currently java8 is the only choice to build TiSpark, run mvn -version to check.

git clone https://github.com/pingcap/tispark.git

To build all TiSpark modules from sources, run the following command under the TiSpark root directory:

mvn clean install -Dmaven.test.skip=true

To skip the tests that you do not need to run, add -Dmaven.test.skip=true.

How to choose TiSpark Version

TiSpark Version TiDB/TiKV/PD Version Spark Version Scala Version
2.1.x <= 3.0.2 2.3.x, 2.4.x 2.11
2.3.x <= 4.0.x 2.3.x, 2.4.x 2.11
2.4.x <= 5.0.x 2.3.x, 2.4.x 2.11
2.5.x <= 5.0.x 3.0.x 2.12

How to upgrade from Spark 2.1 to Spark 2.3/2.4

For the users of Spark 2.1 who wish to upgrade to the latest TiSpark version on Spark 2.3/2.4, download or install Spark 2.3+/2.4+ by following the instructions on Apache Spark Site and overwrite the old spark version in $SPARK_HOME.

TiSpark Architecture

The figure below show the architecture of TiSpark.

architecture

  • TiSpark integrates well with the Spark Catalyst Engine. It provides precise control of computing, which allows Spark to read data from TiKV efficiently. It also supports index seek, which significantly improves the performance of the point query execution.
  • It utilizes several strategies to push down computing to reduce the size of dataset handling by Spark SQL, which accelerates query execution. It also uses the TiDB built-in statistical information for the query plan optimization.
  • From the perspective of data integration, TiSpark + TiDB provides a solution that performs 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 the 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 data source for machine learning, generating reports from the scheduling system and so on.

TiSpark relies on the availability of TiKV clusters and PDs. You also need to set up and use the Spark clustering platform.

Most of the TiSpark logic is inside a thin layer, namely, the tikv-client library.

Quick Start

Before everything starts,

  • add spark.sql.extensions org.apache.spark.sql.TiExtensions in spark-defaults.conf.
  • ensure that spark.tispark.pd.addresses is set correctly.

From Spark-shell:

./bin/spark-shell --jars /wherever-it-is/tispark-${name_with_version}.jar

For TiSpark version >= 2.0:

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

For TiSpark version < 2.0:

import org.apache.spark.sql.TiContext
val ti = new TiContext (spark)
ti.tidbMapDatabase ("tpch_test")

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

Note:

If you use TiSpark 2.0+, for spark-submit on Pyspark, tidbMapDatabase is still required and TiExtension is not supported yet. PingCAP is working on this issue.

Current Version

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

Write Data To TiDB using TiDB Connector

TiSpark natively supports writing data to TiKV via Spark Data Source API and guarantees ACID.

For example:

// tispark will send `lock table` command to TiDB via JDBC
val tidbOptions: Map[String, String] = Map(
  "tidb.addr" -> "127.0.0.1",
  "tidb.password" -> "",
  "tidb.port" -> "4000",
  "tidb.user" -> "root",
  "spark.tispark.pd.addresses" -> "127.0.0.1:2379"
)

val customer = spark.sql("select * from customer limit 100000")

customer.write
.format("tidb")
.option("database", "tpch_test")
.option("table", "cust_test_select")
.mode("append")
.save()

See here for more details.

Configuration

The configurations in the table below can be put together with spark-defaults.conf or passed in the same way as other Spark configuration properties.

Key Default Value Description
spark.tispark.pd.addresses 127.0.0.1:2379 The addresses of PD cluster, which are split by comma
spark.tispark.grpc.framesize 2147483647 The maximum frame size of gRPC response in bytes (default 2G)
spark.tispark.grpc.timeout_in_sec 10 The gRPC timeout time in seconds
spark.tispark.plan.allow_agg_pushdown true Whether aggregations are allowed to push down to TiKV (in case of busy TiKV nodes)
spark.tispark.plan.allow_index_read true Whether index is enabled in planning (which might cause heavy pressure on TiKV)
spark.tispark.index.scan_batch_size 20000 The number of row key in batch for the concurrent index scan
spark.tispark.index.scan_concurrency 5 The maximal number of threads for index scan that retrieves row keys (shared among tasks inside each JVM)
spark.tispark.table.scan_concurrency 512 The maximal number of threads for table scan (shared among tasks inside each JVM)
spark.tispark.request.command.priority Low The value options are Low, Normal, High. This setting impacts the resource to get in TiKV. Low is recommended because the OLTP workload is not disturbed.
spark.tispark.coprocess.codec_format chblock choose the default codec format for coprocessor, available options are default, chblock, chunk
spark.tispark.coprocess.streaming false Whether to use streaming for response fetching (experimental)
spark.tispark.plan.unsupported_pushdown_exprs `` A comma-separated list of expressions. In case you have a very old version of TiKV, you might disable some of the expression push-down if they are not supported.
spark.tispark.plan.downgrade.index_threshold 1000000000 If the range of index scan on one Region exceeds this limit in the original request, downgrade this Region's request to table scan rather than the planned index scan. By default, the downgrade is disabled.
spark.tispark.show_rowid false Whether to show the implicit row ID if the ID exists
spark.tispark.db_prefix `` The string that indicates the extra prefix for all databases in TiDB. This string distinguishes the databases in TiDB from the Hive databases with the same name.
spark.tispark.request.isolation.level SI Isolation level means whether to resolve locks for the underlying TiDB clusters. When you use the "RC", you get the latest version of record smaller than your tso and ignore the locks. If you use "SI", you resolve the locks and get the records depending on whether the resolved lock is committed or aborted.
spark.tispark.coprocessor.chunk_batch_size 1024 How many rows fetched from Coprocessor
spark.tispark.isolation_read_engines tikv,tiflash List of readable engines of TiSpark, comma separated, storage engines not listed will not be read

Spark-3.0 Catalog

Please use the following configurations to enable Catalog provided by spark-3.0.

spark.sql.catalog.tidb_catalog org.apache.spark.sql.catalyst.catalog.TiCatalog
spark.sql.catalog.tidb_catalog.pd.addresses 127.0.0.1:2379

Log4j Configuration

When you start spark-shell or spark-sql and run query, you might see the following warnings:

Failed to get database ****, returning NoSuchObjectException
Failed to get database ****, returning NoSuchObjectException

where **** is the name of database.

The warnings are benign and occurs because Spark cannot find **** in its own catalog. You can just ignore these warnings.

To mute them, append the following text to ${SPARK_HOME}/conf/log4j.properties.

# tispark disable "WARN ObjectStore:568 - Failed to get database"
log4j.logger.org.apache.hadoop.hive.metastore.ObjectStore=ERROR

Time Zone

Set time zone by using the -Duser.timezone system property (for example, -Duser.timezone=GMT-7), which affects the Timestamp type.

Do not use spark.sql.session.timeZone.

Statistics information

For how TiSpark can benefit from TiDB's statistic information, see here.

Compatibility with TiDB

View

TiDB starts to support view since tidb-3.0.

TiSpark currently does not support view. Users are not be able to observe or access data through view with TiSpark.

Table Partition

tidb-3.0 supports both Range Partition and Hash Partition.

TiSpark currently supports Range Partition and Hash Partition. Users can select data from the Range Partition table and the Hash Partition table through TiSpark.

In most cases, TiSpark use a full table scan on partition tables. Only in certain cases, TiSpark applies partition pruning. For more details, see here.

Expression Index

tidb-5.0 supports Expression Index.

TiSpark currently supports retrieving data from table with Expression Index, but the Expression Index will not be used by the planner of TiSpark.

Upgrade from TiDB-2.x to TiDB-3.x

When upgrading from TiDB-2.x to TiDB-3.x,

  1. make sure that you are using at least TiSpark-2.1.2 (TiSpark-2.1.9 is highly recommended).
  2. tidbMapDatabase is deprecated after TiSpark-2.x, make sure that you are not using it.

Example Programs

There are some sample programs for TiSpark. You can run them locally or on a cluster following the document.

How to test

TiDB uses docker-compose to provide the TiDB cluster service which allows you to run test across different platforms.

It is recommended to install Docker to conduct the test locally, or to set up your own TiDB cluster locally as you wish.

For the former method, you can use docker-compose up -d to launch TiDB cluster service under the home directory of TiSpark. To see the logs of TiDB cluster, launch TiDB cluster service via docker-compose up. To shut down the entire TiDB cluster service, use docker-compose down. All the data is stored in the data directory at the root of this project. You can change it as you like.

For more details about the test, see here.

Limitations

  1. Spark config spark.sql.runSQLOnFiles should not be set to false, or you may got Error in query: Table or view not found error.

  2. Spark command show create table can't display tables in TiDB.

  3. Using the style of "{db}.{table}.{colname}" in the condition is not supported, e.g. select * from t where db.t.col1 = 1.

  4. Null in aggregration is not supported, e.g. select sum(null) from t group by col1.

Follow us

Twitter

@PingCAP

Mailing list

tidb-user@googlegroups.com

Google Group

License

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