Impala各版本新特性

自0.3之后的重点新特性

1.0

·        支持ALTER TABLE。

·        支持通过Hints指定join策略。支持的Hints：

o    [broadcast]：broadcast join策略（将小表放到所有节点上与大表进行分片join）

o    [shuffle]：   partitionedjoin策略（分片join）

·        支持刷新单个表的元数据。元数据的自动刷新仍然不支持。

·        动态资源管理，允许高并发的查询。

0.7

·        支持Parquet文件格式。Parquet是列存储的格式，对查询特别是面向列的查询性能提升有非常大的提升。

·        支持Avro。

·        支持内存限制。之前Impala进程对内存使用没有限制，会造成节点内存耗尽。

·        通过提供broadcast join提供更大和更快的join。

·        完全分布式的聚合（aggregations）计算。之前的计算需要所有数据拖到一个节点上进行聚合处理。

·        完全分布式的top计算。之前的计算需要所有数据拖到一个节点上进行top处理。

·        支持创建和修改表。

·        支持对floats和doubles 的GROUP BY。

0.6.

·        支持SUSE和Debian/Ubuntu，目前支持以下OS：

o    RHEL5.7/6.2 and Centos5.7/6.2

o    SUSE 11 with Service Pack 1 or later

o    Ubuntu 10.04/12.04 and Debian 6.03

·        支持RCFile文件格式。

0.5

·        添加JDBC驱动，运行用户从java客户端访问Impala。

附录：Impala各版本新特性历史

New Features inImpala

Impala contains the following changesand enhancements from previous releases.

New Features in Impala Version 1.0

This version has multiple performance improvementsand adds the following functionality:

·        Several bug fixes. See KnownIssues Fixed in the 1.0 GA Release.

·        ALTER TABLE statement.

·        Hints to allow specifying a particularjoin strategy.

·        REFRESH for a single table.

·        Dynamic resource management, allowing high concurrencyfor Impala queries.

New Features in Version 0.7 of theCloudera Impala Beta Release

This version has multiple performanceimprovements and adds the following functionality:

·        Several bug fixes. See KnownIssues Fixed in Version 0.7 of the Beta Release.

·        Support for the Parquet file format. For more informationon file formats, see UnderstandingFile Formats.

·        Added support for Avro.

·        Support for the memory limits. For more information, seethe example on modifying memory limits in ModifyingImpala Startup Options.

·        Bigger and faster joins through the addition ofpartitioned joins to the already supported broadcast joins.

·        Fully distributed aggregations.

·        Fully distributed top-n computation.

·        Support for creating and altering tables.

·        Support for GROUP BY with floats and doubles.

In this version, both CDH4.1 and 4.2 aresupported, but due to performance improvements added, we highly recommend youuse CDH4.2 to see the full benefit. If you are using Cloudera Manager, version4.5 is required.

New Features in Version 0.6 of theCloudera Impala Beta Release

·        Several bug fixes. See KnownIssues Fixed in Version 0.6 of the Beta Release.

·        Added support for Impala on SUSE and Debian/Ubuntu.Impala is now supported on:

o    RHEL5.7/6.2 and Centos5.7/6.2

o    SUSE 11 with Service Pack 1 or later

o    Ubuntu 10.04/12.04 and Debian 6.03

·        Cloudera Manager 4.5 and CDH 4.2 support Impala 0.6.

·        Support for the RCFile file format. For more informationon file formats, see UnderstandingFile Formats.

New Features in Version 0.5 of theCloudera Impala Beta Release

·        Several bug fixes. See KnownIssues Fixed in Version 0.5 of the Beta Release.

·        Added support for a JDBC driver that allows you to accessImpala from a Java client. To use this feature, you must follow theinstructions in ConfiguringImpala to Work with JDBC to install the JDBC driver JARs onthe client machine and modify the classpath on the client to include the JARs.

New Features in Version 0.4 of theCloudera Impala Beta Release

·        Several bug fixes. See KnownIssues Fixed in Version 0.4 of the Beta Release.

·        Added support for Impala on RHEL5.7/Centos5.7. Impala isnow supported on RHEL5.7/6.2 and Centos5.7/6.2.

·        Cloudera Manager 4.1.3 supports Impala 0.4.

·        The Impala debug webserver now has the ability to servestatic files from ${IMPALA_HOME}/www. This can be disabled by setting --enable_webserver_doc_root=false on the command line. As a result,Impala now uses the Twitter Bootstrap library to style its debug webpages, andthe /queriespage now tracksthe last 25 queries run by each Impala daemon.

·        Additional metrics available on the Impala Debug Webpage.

New Features in Version 0.3 of theCloudera Impala Beta Release

·        Several bug fixes. See KnownIssues Fixed in Version 0.3 of the Beta Release.

·        The state-store-service binary has been renamed statestored.

·        The location of the Impala configuration files haschanged from the /usr/lib/impala/conf directory to the /etc/impala/conf directory.

New Features in Version 0.2 of theCloudera Impala Beta Release

·        Several bug fixes. See KnownIssues Fixed in Version 0.2 of the Beta Release.

·        Added Default Query Options Default query options override alldefault QueryOption values when starting impalad. The format is: