commit | 626014eaf093fc2e3b53f5ad00c425bc209e1428 | [log] [tgz] |
---|---|---|
author | Ryan Blue <blue@apache.org> | Sun Jul 17 14:59:20 2016 -0700 |
committer | Ryan Blue <blue@apache.org> | Sun Jul 17 14:59:20 2016 -0700 |
tree | 05659fc5cb210d27a869186a4897f73cf77b9ca8 | |
parent | a421d952efd85ec581131069a5b132934ee286d3 [diff] |
PARQUET-651: Improve Avro's isElementType check. The Avro implementation needs to check whether the read schema that is passed by the user (or automatically converted from the file schema) expects an extra 1-field layer to be returned, which matches the previous behavior of Avro when reading a 3-level list. Before this commit, the check was done by testing the structure of the expected list element type against the repeated group's schema. If they matched, then Avro assumed that the user expected an extra layer. However, for records that happened to match (1-field records with a field named "element") the check could be wrong and would cause exceptions later. This commit updates the check to convert the file's element schema to Avro and compare the compatibility of that schema with what was passed by the user. This checks the entire tree from the element down and gets the answer right based on the element and its children, not just the field names on the element. Author: Ryan Blue <blue@apache.org> Closes #352 from rdblue/PARQUET-651-improve-is-element-type-check and squashes the following commits: ad9c1ee [Ryan Blue] PARQUET-651: Undo accidental default setting change. 1efa248 [Ryan Blue] PARQUET-651: Improve Avro's isElementType check.
Parquet-MR contains the java implementation of the Parquet format. Parquet is a columnar storage format for Hadoop; it provides efficient storage and encoding of data. Parquet uses the record shredding and assembly algorithm described in the Dremel paper to represent nested structures.
You can find some details about the format and intended use cases in our Hadoop Summit 2013 presentation
Parquet-MR uses Maven to build and depends on both the thrift and protoc compilers.
To build and install the protobuf compiler, run:
wget http://protobuf.googlecode.com/files/protobuf-2.5.0.tar.gz tar xzf protobuf-2.5.0.tar.gz cd protobuf-2.5.0 ./configure make sudo make install sudo ldconfig
To build and install the thrift compiler, run:
wget -nv http://archive.apache.org/dist/thrift/0.7.0/thrift-0.7.0.tar.gz tar xzf thrift-0.7.0.tar.gz cd thrift-0.7.0 chmod +x ./configure ./configure --disable-gen-erl --disable-gen-hs --without-ruby --without-haskell --without-erlang sudo make install
Once protobuf and thrift are available in your path, you can build the project by running:
LC_ALL=C mvn clean install
Parquet is a very active project, and new features are being added quickly; below is the state as of June 2013.
Input and Output formats. Note that to use an Input or Output format, you need to implement a WriteSupport or ReadSupport class, which will implement the conversion of your object to and from a Parquet schema.
We've implemented this for 2 popular data formats to provide a clean migration path as well:
Thrift integration is provided by the parquet-thrift sub-project. If you are using Thrift through Scala, you may be using Twitter‘s Scrooge. If that’s the case, not to worry -- we took care of the Scrooge/Apache Thrift glue for you in the parquet-scrooge sub-project.
Avro conversion is implemented via the parquet-avro sub-project.
See the APIs:
A Loader and a Storer are provided to read and write Parquet files with Apache Pig
Storing data into Parquet in Pig is simple:
-- options you might want to fiddle with SET parquet.page.size 1048576 -- default. this is your min read/write unit. SET parquet.block.size 134217728 -- default. your memory budget for buffering data SET parquet.compression lzo -- or you can use none, gzip, snappy STORE mydata into '/some/path' USING parquet.pig.ParquetStorer;
Reading in Pig is also simple:
mydata = LOAD '/some/path' USING parquet.pig.ParquetLoader();
If the data was stored using Pig, things will “just work”. If the data was stored using another method, you will need to provide the Pig schema equivalent to the data you stored (you can also write the schema to the file footer while writing it -- but that's pretty advanced). We will provide a basic automatic schema conversion soon.
Hive integration is provided via the parquet-hive sub-project.
to run the unit tests: mvn test
to build the jars: mvn package
The build runs in Travis CI:
The current release is version 1.8.1
<dependencies> <dependency> <groupId>org.apache.parquet</groupId> <artifactId>parquet-common</artifactId> <version>1.8.1</version> </dependency> <dependency> <groupId>org.apache.parquet</groupId> <artifactId>parquet-encoding</artifactId> <version>1.8.1</version> </dependency> <dependency> <groupId>org.apache.parquet</groupId> <artifactId>parquet-column</artifactId> <version>1.8.1</version> </dependency> <dependency> <groupId>org.apache.parquet</groupId> <artifactId>parquet-hadoop</artifactId> <version>1.8.1</version> </dependency> </dependencies>
We prefer to receive contributions in the form of GitHub pull requests. Please send pull requests against the github.com/apache/parquet-mr repository. If you've previously forked Parquet from its old location, you will need to add a remote or update your origin remote to https://github.com/apache/parquet-mr.git
If you are looking for some ideas on what to contribute, check out jira issues for this project labeled “pick-me-up”. Comment on the issue and/or contact dev@parquet.apache.org with your questions and ideas.
If you’d like to report a bug but don’t have time to fix it, you can still post it to our issue tracker, or email the mailing list dev@parquet.apache.org
To contribute a patch:
mvn test
in the root directory.We tend to do fairly close readings of pull requests, and you may get a lot of comments. Some common issues that are not code structure related, but still important:
a+b
but a + b
and not foo(int a,int b)
but foo(int a, int b)
.Thank you for getting involved!
We hold ourselves and the Parquet developer community to two codes of conduct:
Licensed under the Apache License, Version 2.0: http://www.apache.org/licenses/LICENSE-2.0 See also: