Hi Josh,

I've just committed the map side joins, after doing some more
extensive testing on it today. Unfortunately, I forgot to squash the
multiple commits into a single one (as I was planning on doing), but
it's all in there and working.

- Gabriel

On Fri, Jul 6, 2012 at 7:28 AM, Gabriel Reid <[email protected]> wrote:
> Thanks for making the JIRA issue.
>
> I was going to do some more testing an a "real" cluster later on today, and 
> as long as that all checks out then this will be ready to go in as far as I'm 
> concerned.
>
> I don't see any reason to hold back on the big renaming for this patch -- if 
> you're ready to do the package renaming, please go ahead.
>
> As long as my testing later today checks out and there aren't any glaring 
> issues from anyone who has tried the patch out, I'll probably be checking the 
> patch in later today (so it'll probably be in before you do the renaming 
> anyhow).
>
> - Gabriel
>
>
> On Friday 6 July 2012 at 00:11, Josh Wills wrote:
>
>> FYI: https://issues.apache.org/jira/browse/CRUNCH-3 to track this.
>>
>> Gabriel, is your feeling that this is ready to go in? I'm debating whether
>> or not to check this in before/after I do the massive com.cloudera ->
>> org.apache renaming. What do you think?
>>
>> On Tue, Jul 3, 2012 at 1:25 PM, Gabriel Reid <[email protected] 
>> (mailto:[email protected])> wrote:
>>
>> > Hi Joe,
>> >
>> > Looking forward to hearing your feedback! This is still just a patch and
>> > not committed yet, and there's still definitely room for help (i.e. ideas
>> > on how to improve it, or do it totally differently), so certainly let me
>> > know if you've got some ideas.
>> >
>> > - Gabriel
>> >
>> >
>> > On Tuesday 3 July 2012 at 18:01, Joseph Adler wrote:
>> >
>> > > Awesome! Will give this a try soon... wish I could have helped with this
>> > one...
>> > >
>> > > On Tue, Jul 3, 2012 at 1:53 AM, Gabriel Reid <[email protected] 
>> > > (mailto:[email protected])(mailto:
>> > [email protected] (mailto:[email protected]))> wrote:
>> > > > Thanks for pointing that out Chris. I'm guessing the mailing list is
>> > > > stripping out attachments(?). Once the JIRA is up and running then
>> > > > that will be taken care of I guess.
>> > > >
>> > > > The mime type on the last attempt was application/octet-stream, so
>> > > > I've renamed this to a .txt file to try to ensure that it'll get a
>> > > > text/plain mime type (although I don't know if that'll make a
>> > > > difference). I've also pasted it inline below, hopefully one of those
>> > > > solutions works.
>> > > >
>> > > > - Gabriel
>> > > >
>> > > >
>> > > > diff --git src/main/java/com/cloudera/crunch/impl/mr/MRPipeline.java
>> > > > src/main/java/com/cloudera/crunch/impl/mr/MRPipeline.java
>> > > > index 420e8dc..c8ba596 100644
>> > > > --- src/main/java/com/cloudera/crunch/impl/mr/MRPipeline.java
>> > > > +++ src/main/java/com/cloudera/crunch/impl/mr/MRPipeline.java
>> > > > @@ -59,9 +59,9 @@ import com.google.common.collect.Sets;
>> > > > public class MRPipeline implements Pipeline {
>> > > >
>> > > > private static final Log LOG = LogFactory.getLog(MRPipeline.class);
>> > > > -
>> > > > +
>> > > > private static final Random RANDOM = new Random();
>> > > > -
>> > > > +
>> > > > private final Class<?> jarClass;
>> > > > private final String name;
>> > > > private final Map<PCollectionImpl<?>, Set<Target>> outputTargets;
>> > > > @@ -75,15 +75,15 @@ public class MRPipeline implements Pipeline {
>> > > > public MRPipeline(Class<?> jarClass) throws IOException {
>> > > > this(jarClass, new Configuration());
>> > > > }
>> > > > -
>> > > > - public MRPipeline(Class<?> jarClass, String name){
>> > > > +
>> > > > + public MRPipeline(Class<?> jarClass, String name) {
>> > > > this(jarClass, name, new Configuration());
>> > > > }
>> > > > -
>> > > > +
>> > > > public MRPipeline(Class<?> jarClass, Configuration conf) {
>> > > > - this(jarClass, jarClass.getName(), conf);
>> > > > + this(jarClass, jarClass.getName(), conf);
>> > > > }
>> > > > -
>> > > > +
>> > > > public MRPipeline(Class<?> jarClass, String name, Configuration conf) {
>> > > > this.jarClass = jarClass;
>> > > > this.name (http://this.name) = name;
>> > > > @@ -102,9 +102,9 @@ public class MRPipeline implements Pipeline {
>> > > >
>> > > > @Override
>> > > > public void setConfiguration(Configuration conf) {
>> > > > - this.conf = conf;
>> > > > + this.conf = conf;
>> > > > }
>> > > > -
>> > > > +
>> > > > @Override
>> > > > public PipelineResult run() {
>> > > > MSCRPlanner planner = new MSCRPlanner(this, outputTargets);
>> > > > @@ -125,8 +125,8 @@ public class MRPipeline implements Pipeline {
>> > > > boolean materialized = false;
>> > > > for (Target t : outputTargets.get(c)) {
>> > > > if (!materialized && t instanceof Source) {
>> > > > - c.materializeAt((SourceTarget) t);
>> > > > - materialized = true;
>> > > > + c.materializeAt((SourceTarget) t);
>> > > > + materialized = true;
>> > > > }
>> > > > }
>> > > > }
>> > > > @@ -144,7 +144,7 @@ public class MRPipeline implements Pipeline {
>> > > > cleanup();
>> > > > return res;
>> > > > }
>> > > > -
>> > > > +
>> > > > public <S> PCollection<S> read(Source<S> source) {
>> > > > return new InputCollection<S>(source, this);
>> > > > }
>> > > > @@ -160,85 +160,120 @@ public class MRPipeline implements Pipeline {
>> > > > @SuppressWarnings("unchecked")
>> > > > public void write(PCollection<?> pcollection, Target target) {
>> > > > if (pcollection instanceof PGroupedTableImpl) {
>> > > > - pcollection = ((PGroupedTableImpl<?,?>) pcollection).ungroup();
>> > > > + pcollection = ((PGroupedTableImpl<?, ?>) pcollection).ungroup();
>> > > > } else if (pcollection instanceof UnionCollection || pcollection
>> > > > instanceof UnionTable) {
>> > > > - pcollection = pcollection.parallelDo("UnionCollectionWrapper",
>> > > > - (MapFn)IdentityFn.<Object>getInstance(), pcollection.getPType());
>> > > > + pcollection = pcollection.parallelDo("UnionCollectionWrapper",
>> > > > + (MapFn) IdentityFn.<Object> getInstance(), pcollection.getPType());
>> > > > }
>> > > > addOutput((PCollectionImpl<?>) pcollection, target);
>> > > > }
>> > > >
>> > > > private void addOutput(PCollectionImpl<?> impl, Target target) {
>> > > > if (!outputTargets.containsKey(impl)) {
>> > > > - outputTargets.put(impl, Sets.<Target>newHashSet());
>> > > > + outputTargets.put(impl, Sets.<Target> newHashSet());
>> > > > }
>> > > > outputTargets.get(impl).add(target);
>> > > > }
>> > > > -
>> > > > +
>> > > > @Override
>> > > > public <T> Iterable<T> materialize(PCollection<T> pcollection) {
>> > > > -
>> > > > - if (pcollection instanceof UnionCollection) {
>> > > > - pcollection = pcollection.parallelDo("UnionCollectionWrapper",
>> > > > - (MapFn)IdentityFn.<Object>getInstance(), pcollection.getPType());
>> > > > - }
>> > > > - PCollectionImpl<T> impl = (PCollectionImpl<T>) pcollection;
>> > > > +
>> > > > + PCollectionImpl<T> pcollectionImpl = toPcollectionImpl(pcollection);
>> > > > + ReadableSourceTarget<T> srcTarget =
>> > > > getMaterializeSourceTarget(pcollectionImpl);
>> > > > +
>> > > > + MaterializableIterable<T> c = new MaterializableIterable<T>(this,
>> > > > srcTarget);
>> > > > + if (!outputTargetsToMaterialize.containsKey(pcollectionImpl)) {
>> > > > + outputTargetsToMaterialize.put(pcollectionImpl, c);
>> > > > + }
>> > > > + return c;
>> > > > + }
>> > > > +
>> > > > + /**
>> > > > + * Retrieve a ReadableSourceTarget that provides access to the
>> > >
>> >
>> >
>> > contents of a
>> > > > + * {@link PCollection}. This is primarily intended as a helper method
>> > >
>> >
>> >
>> > to
>> > > > + * {@link #materialize(PCollection)}. The underlying data of the
>> > > > + * ReadableSourceTarget may not be actually present until the
>> > > > pipeline is run.
>> > > > + *
>> > > > + * @param pcollection
>> > > > + * The collection for which the ReadableSourceTarget is to be
>> > > > + * retrieved
>> > > > + * @return The ReadableSourceTarget
>> > > > + * @throws IllegalArgumentException
>> > > > + * If no ReadableSourceTarget can be retrieved for the given
>> > > > + * PCollection
>> > > > + */
>> > > > + public <T> ReadableSourceTarget<T>
>> > > > getMaterializeSourceTarget(PCollection<T> pcollection) {
>> > > > + PCollectionImpl<T> impl = toPcollectionImpl(pcollection);
>> > > > SourceTarget<T> matTarget = impl.getMaterializedAt();
>> > > > if (matTarget != null && matTarget instanceof ReadableSourceTarget) {
>> > > > - return new MaterializableIterable<T>(this,
>> > > > (ReadableSourceTarget<T>) matTarget);
>> > > > + return (ReadableSourceTarget<T>) matTarget;
>> > > > + }
>> > > > +
>> > > > + ReadableSourceTarget<T> srcTarget = null;
>> > > > + if (outputTargets.containsKey(pcollection)) {
>> > > > + for (Target target : outputTargets.get(impl)) {
>> > > > + if (target instanceof ReadableSourceTarget) {
>> > > > + srcTarget = (ReadableSourceTarget<T>) target;
>> > > > + break;
>> > > > + }
>> > > > + }
>> > > > }
>> > > > -
>> > > > - ReadableSourceTarget<T> srcTarget = null;
>> > > > - if (outputTargets.containsKey(pcollection)) {
>> > > > - for (Target target : outputTargets.get(impl)) {
>> > > > - if (target instanceof ReadableSourceTarget) {
>> > > > - srcTarget = (ReadableSourceTarget) target;
>> > > > - break;
>> > > > - }
>> > > > - }
>> > > > - }
>> > > > -
>> > > > - if (srcTarget == null) {
>> > > > - SourceTarget<T> st =
>> > >
>> >
>> >
>> > createIntermediateOutput(pcollection.getPType());
>> > > > - if (!(st instanceof ReadableSourceTarget)) {
>> > > > - throw new IllegalArgumentException("The PType for the given
>> > > > PCollection is not readable"
>> > > > - + " and cannot be materialized");
>> > > > - } else {
>> > > > - srcTarget = (ReadableSourceTarget) st;
>> > > > - addOutput(impl, srcTarget);
>> > > > - }
>> > > > - }
>> > > > -
>> > > > - MaterializableIterable<T> c = new MaterializableIterable<T>(this,
>> > >
>> >
>> >
>> > srcTarget);
>> > > > - outputTargetsToMaterialize.put(impl, c);
>> > > > - return c;
>> > > > +
>> > > > + if (srcTarget == null) {
>> > > > + SourceTarget<T> st =
>> > >
>> >
>> >
>> > createIntermediateOutput(pcollection.getPType());
>> > > > + if (!(st instanceof ReadableSourceTarget)) {
>> > > > + throw new IllegalArgumentException("The PType for the given
>> > > > PCollection is not readable"
>> > > > + + " and cannot be materialized");
>> > > > + } else {
>> > > > + srcTarget = (ReadableSourceTarget<T>) st;
>> > > > + addOutput(impl, srcTarget);
>> > > > + }
>> > > > + }
>> > > > +
>> > > > + return srcTarget;
>> > > > + }
>> > > > +
>> > > > + /**
>> > > > + * Safely cast a PCollection into a PCollectionImpl, including
>> > > > handling the case of UnionCollections.
>> > > > + * @param pcollection The PCollection to be cast/transformed
>> > > > + * @return The PCollectionImpl representation
>> > > > + */
>> > > > + private <T> PCollectionImpl<T> toPcollectionImpl(PCollection<T>
>> > > > pcollection) {
>> > > > + PCollectionImpl<T> pcollectionImpl = null;
>> > > > + if (pcollection instanceof UnionCollection) {
>> > > > + pcollectionImpl = (PCollectionImpl<T>)
>> > > > pcollection.parallelDo("UnionCollectionWrapper",
>> > > > + (MapFn) IdentityFn.<Object> getInstance(), pcollection.getPType());
>> > > > + } else {
>> > > > + pcollectionImpl = (PCollectionImpl<T>) pcollection;
>> > > > + }
>> > > > + return pcollectionImpl;
>> > > > }
>> > > >
>> > > > public <T> SourceTarget<T> createIntermediateOutput(PType<T> ptype) {
>> > > > - return ptype.getDefaultFileSource(createTempPath());
>> > > > + return ptype.getDefaultFileSource(createTempPath());
>> > > > }
>> > > >
>> > > > public Path createTempPath() {
>> > > > tempFileIndex++;
>> > > > return new Path(tempDirectory, "p" + tempFileIndex);
>> > > > }
>> > > > -
>> > > > +
>> > > > private static Path createTempDirectory(Configuration conf) {
>> > > > Path dir = new Path("/tmp/crunch" + RANDOM.nextInt());
>> > > > - try {
>> > > > - FileSystem.get(conf).mkdirs(dir);
>> > > > - } catch (IOException e) {
>> > > > - LOG.error("Exception creating job output directory", e);
>> > > > - throw new RuntimeException(e);
>> > > > - }
>> > > > + try {
>> > > > + FileSystem.get(conf).mkdirs(dir);
>> > > > + } catch (IOException e) {
>> > > > + LOG.error("Exception creating job output directory", e);
>> > > > + throw new RuntimeException(e);
>> > > > + }
>> > > > return dir;
>> > > > }
>> > > > -
>> > > > +
>> > > > @Override
>> > > > public <T> void writeTextFile(PCollection<T> pcollection, String
>> > >
>> >
>> >
>> > pathName) {
>> > > > // Ensure that this is a writable pcollection instance.
>> > > > - pcollection = pcollection.parallelDo("asText",
>> > >
>> >
>> >
>> > IdentityFn.<T>getInstance(),
>> > > > - WritableTypeFamily.getInstance().as(pcollection.getPType()));
>> > > > + pcollection = pcollection.parallelDo("asText", IdentityFn.<T>
>> > > > getInstance(), WritableTypeFamily
>> > > > + .getInstance().as(pcollection.getPType()));
>> > > > write(pcollection, At.textFile(pathName));
>> > > > }
>> > > >
>> > > > @@ -256,7 +291,7 @@ public class MRPipeline implements Pipeline {
>> > > > LOG.info (http://LOG.info)("Exception during cleanup", e);
>> > > > }
>> > > > }
>> > > > -
>> > > > +
>> > > > public int getNextAnonymousStageId() {
>> > > > return nextAnonymousStageId++;
>> > > > }
>> > > > @@ -265,7 +300,7 @@ public class MRPipeline implements Pipeline {
>> > > > public void enableDebug() {
>> > > > // Turn on Crunch runtime error catching.
>> > > > getConfiguration().setBoolean(RuntimeParameters.DEBUG, true);
>> > > > -
>> > > > +
>> > > > // Write Hadoop's WARN logs to the console.
>> > > > Logger crunchInfoLogger = LogManager.getLogger("com.cloudera.crunch");
>> > > > Appender console = crunchInfoLogger.getAppender("A");
>> > > > @@ -277,9 +312,9 @@ public class MRPipeline implements Pipeline {
>> > > > LOG.warn("Could not find console appender named 'A' for writing
>> > > > Hadoop warning logs");
>> > > > }
>> > > > }
>> > > > -
>> > > > +
>> > > > @Override
>> > > > public String getName() {
>> > > > - return name;
>> > > > + return name;
>> > > > }
>> > > > }
>> > > > diff --git
>> > >
>> >
>> >
>> > src/main/java/com/cloudera/crunch/impl/mr/run/CrunchRuntimeException.java
>> > >
>> >
>> >
>> > src/main/java/com/cloudera/crunch/impl/mr/run/CrunchRuntimeException.java
>> > > > index d41a52e..68ef054 100644
>> > > > ---
>> > >
>> >
>> >
>> > src/main/java/com/cloudera/crunch/impl/mr/run/CrunchRuntimeException.java
>> > > > +++
>> > >
>> >
>> >
>> > src/main/java/com/cloudera/crunch/impl/mr/run/CrunchRuntimeException.java
>> > > > @@ -12,6 +12,10 @@ public class CrunchRuntimeException extends
>> > > > RuntimeException {
>> > > > super(e);
>> > > > }
>> > > >
>> > > > + public CrunchRuntimeException(String msg, Exception e) {
>> > > > + super(msg, e);
>> > > > + }
>> > > > +
>> > > > public boolean wasLogged() {
>> > > > return logged;
>> > > > }
>> > > > diff --git
>> > >
>> >
>> >
>> > src/main/java/com/cloudera/crunch/io/avro/AvroFileSource.java
>> > > > src/main/java/com/cloudera/crunch/io/avro/AvroFileSource.java
>> > > > index 1122d62..4debfeb 100644
>> > > > --- src/main/java/com/cloudera/crunch/io/avro/AvroFileSource.java
>> > > > +++ src/main/java/com/cloudera/crunch/io/avro/AvroFileSource.java
>> > > > @@ -45,7 +45,8 @@ public class AvroFileSource<T> extends
>> > > > FileSourceImpl<T> implements ReadableSour
>> > > >
>> > > > @Override
>> > > > public Iterable<T> read(Configuration conf) throws IOException {
>> > > > - return CompositePathIterable.create(FileSystem.get(conf), path,
>> > > > new AvroFileReaderFactory<T>(
>> > > > + FileSystem fs = FileSystem.get(path.toUri(), conf);
>> > > > + return CompositePathIterable.create(fs, path, new
>> > >
>> >
>> >
>> > AvroFileReaderFactory<T>(
>> > > > (AvroType<T>) ptype, conf));
>> > > > }
>> > > > }
>> > > > diff --git src/main/java/com/cloudera/crunch/io/seq/SeqFileSource.java
>> > > > src/main/java/com/cloudera/crunch/io/seq/SeqFileSource.java
>> > > > index 24dec2d..462ef93 100644
>> > > > --- src/main/java/com/cloudera/crunch/io/seq/SeqFileSource.java
>> > > > +++ src/main/java/com/cloudera/crunch/io/seq/SeqFileSource.java
>> > > > @@ -26,18 +26,16 @@ import com.cloudera.crunch.io.ReadableSource;
>> > > > import com.cloudera.crunch.io.impl.FileSourceImpl;
>> > > > import com.cloudera.crunch.types.PType;
>> > > >
>> > > > -public class SeqFileSource<T> extends FileSourceImpl<T> implements
>> > > > - ReadableSource<T> {
>> > > > +public class SeqFileSource<T> extends FileSourceImpl<T> implements
>> > > > ReadableSource<T> {
>> > > >
>> > > > public SeqFileSource(Path path, PType<T> ptype) {
>> > > > - super(path, ptype, SequenceFileInputFormat.class);
>> > > > + super(path, ptype, SequenceFileInputFormat.class);
>> > > > }
>> > > > -
>> > > > +
>> > > > @Override
>> > > > public Iterable<T> read(Configuration conf) throws IOException {
>> > > > - FileSystem fs = FileSystem.get(conf);
>> > > > - return CompositePathIterable.create(fs, path,
>> > > > - new SeqFileReaderFactory<T>(ptype, conf));
>> > > > + FileSystem fs = FileSystem.get(path.toUri(), conf);
>> > > > + return CompositePathIterable.create(fs, path, new
>> > > > SeqFileReaderFactory<T>(ptype, conf));
>> > > > }
>> > > >
>> > > > @Override
>> > > > diff --git
>> > >
>> >
>> >
>> > src/main/java/com/cloudera/crunch/io/seq/SeqFileTableSource.java
>> > > > src/main/java/com/cloudera/crunch/io/seq/SeqFileTableSource.java
>> > > > index 69ca12b..4db6658 100644
>> > > > --- src/main/java/com/cloudera/crunch/io/seq/SeqFileTableSource.java
>> > > > +++ src/main/java/com/cloudera/crunch/io/seq/SeqFileTableSource.java
>> > > > @@ -42,7 +42,7 @@ public class SeqFileTableSource<K, V> extends
>> > > > FileTableSourceImpl<K, V> implemen
>> > > >
>> > > > @Override
>> > > > public Iterable<Pair<K, V>> read(Configuration conf) throws
>> > >
>> >
>> >
>> > IOException {
>> > > > - FileSystem fs = FileSystem.get(conf);
>> > > > + FileSystem fs = FileSystem.get(path.toUri(), conf);
>> > > > return CompositePathIterable.create(fs, path,
>> > > > new SeqFileTableReaderFactory<K, V>((PTableType<K, V>) ptype, conf));
>> > > > }
>> > > > diff --git
>> > >
>> >
>> >
>> > src/main/java/com/cloudera/crunch/io/text/TextFileSource.java
>> > > > src/main/java/com/cloudera/crunch/io/text/TextFileSource.java
>> > > > index a876843..e0dbe68 100644
>> > > > --- src/main/java/com/cloudera/crunch/io/text/TextFileSource.java
>> > > > +++ src/main/java/com/cloudera/crunch/io/text/TextFileSource.java
>> > > > @@ -67,7 +67,7 @@ public class TextFileSource<T> extends
>> > > > FileSourceImpl<T> implements
>> > > >
>> > > > @Override
>> > > > public Iterable<T> read(Configuration conf) throws IOException {
>> > > > - return CompositePathIterable.create(FileSystem.get(conf), path,
>> > > > - new TextFileReaderFactory<T>(ptype, conf));
>> > > > + return CompositePathIterable.create(FileSystem.get(path.toUri(),
>> > > > conf), path,
>> > > > + new TextFileReaderFactory<T>(ptype, conf));
>> > > > }
>> > > > }
>> > > > diff --git src/main/java/com/cloudera/crunch/lib/join/MapsideJoin.java
>> > > > src/main/java/com/cloudera/crunch/lib/join/MapsideJoin.java
>> > > > new file mode 100644
>> > > > index 0000000..8072e07
>> > > > --- /dev/null
>> > > > +++ src/main/java/com/cloudera/crunch/lib/join/MapsideJoin.java
>> > > > @@ -0,0 +1,143 @@
>> > > > +package com.cloudera.crunch.lib.join;
>> > > > +
>> > > > +import java.io.IOException;
>> > > > +
>> > > > +import org.apache.hadoop.filecache.DistributedCache;
>> > > > +import org.apache.hadoop.fs.FileSystem;
>> > > > +import org.apache.hadoop.fs.Path;
>> > > > +
>> > > > +import com.cloudera.crunch.DoFn;
>> > > > +import com.cloudera.crunch.Emitter;
>> > > > +import com.cloudera.crunch.PTable;
>> > > > +import com.cloudera.crunch.Pair;
>> > > > +import com.cloudera.crunch.impl.mr.MRPipeline;
>> > > > +import com.cloudera.crunch.impl.mr.run.CrunchRuntimeException;
>> > > > +import com.cloudera.crunch.io.ReadableSourceTarget;
>> > > > +import com.cloudera.crunch.io.impl.SourcePathTargetImpl;
>> > > > +import com.cloudera.crunch.types.PType;
>> > > > +import com.cloudera.crunch.types.PTypeFamily;
>> > > > +import com.google.common.collect.ArrayListMultimap;
>> > > > +import com.google.common.collect.Multimap;
>> > > > +
>> > > > +/**
>> > > > + * Utility for doing map side joins on a common key between two
>> > > > {@link PTable}s.
>> > > > + * <p>
>> > > > + * A map side join is an optimized join which doesn't use a reducer;
>> > >
>> >
>> >
>> > instead,
>> > > > + * the right side of the join is loaded into memory and the join is
>> > > > performed in
>> > > > + * a mapper. This style of join has the important implication that
>> > > > the output of
>> > > > + * the join is not sorted, which is the case with a conventional
>> > > > (reducer-based)
>> > > > + * join.
>> > > > + * <p>
>> > > > + * <b>Note:</b>This utility is only supported when running with a
>> > > > + * {@link MRPipeline} as the pipeline.
>> > > > + */
>> > > > +public class MapsideJoin {
>> > > > +
>> > > > + /**
>> > > > + * Join two tables using a map side join. The right-side table will
>> > >
>> >
>> >
>> > be loaded
>> > > > + * fully in memory, so this method should only be used if the right
>> > >
>> >
>> >
>> > side
>> > > > + * table's contents can fit in the memory allocated to mappers. The
>> > >
>> >
>> >
>> > join
>> > > > + * performed by this method is an inner join.
>> > > > + *
>> > > > + * @param left
>> > > > + * The left-side table of the join
>> > > > + * @param right
>> > > > + * The right-side table of the join, whose contents will be fully
>> > > > + * read into memory
>> > > > + * @return A table keyed on the join key, containing pairs of joined
>> > >
>> >
>> >
>> > values
>> > > > + */
>> > > > + public static <K, U, V> PTable<K, Pair<U, V>> join(PTable<K, U>
>> > > > left, PTable<K, V> right) {
>> > > > +
>> > > > + if (!(right.getPipeline() instanceof MRPipeline)) {
>> > > > + throw new CrunchRuntimeException("Map-side join is only
>> > > > supported within a MapReduce context");
>> > > > + }
>> > > > +
>> > > > + MRPipeline pipeline = (MRPipeline) right.getPipeline();
>> > > > + pipeline.materialize(right);
>> > > > +
>> > > > + // TODO Move necessary logic to MRPipeline so that we can
>> > >
>> >
>> >
>> > theoretically
>> > > > + // optimize his by running the setup of multiple map-side joins
>> > > > concurrently
>> > > > + pipeline.run();
>> > > > +
>> > > > + ReadableSourceTarget<Pair<K, V>> readableSourceTarget = pipeline
>> > > > + .getMaterializeSourceTarget(right);
>> > > > + if (!(readableSourceTarget instanceof SourcePathTargetImpl)) {
>> > > > + throw new CrunchRuntimeException("Right-side contents can't be
>> > > > read from a path");
>> > > > + }
>> > > > +
>> > > > + // Suppress warnings because we've just checked this cast via
>> > >
>> >
>> >
>> > instanceof
>> > > > + @SuppressWarnings("unchecked")
>> > > > + SourcePathTargetImpl<Pair<K, V>> sourcePathTarget =
>> > > > (SourcePathTargetImpl<Pair<K, V>>) readableSourceTarget;
>> > > > +
>> > > > + Path path = sourcePathTarget.getPath();
>> > > > + DistributedCache.addCacheFile(path.toUri(),
>> > >
>> >
>> >
>> > pipeline.getConfiguration());
>> > > > +
>> > > > + MapsideJoinDoFn<K, U, V> mapJoinDoFn = new MapsideJoinDoFn<K, U,
>> > > > V>(path.toString(),
>> > > > + right.getPType());
>> > > > + PTypeFamily typeFamily = left.getTypeFamily();
>> > > > + return left.parallelDo(
>> > > > + "mapjoin",
>> > > > + mapJoinDoFn,
>> > > > + typeFamily.tableOf(left.getKeyType(),
>> > > > + typeFamily.pairs(left.getValueType(), right.getValueType())));
>> > > > +
>> > > > + }
>> > > > +
>> > > > + static class MapsideJoinDoFn<K, U, V> extends DoFn<Pair<K, U>,
>> > > > Pair<K, Pair<U, V>>> {
>> > > > +
>> > > > + private String inputPath;
>> > > > + private PType<Pair<K, V>> ptype;
>> > > > + private Multimap<K, V> joinMap;
>> > > > +
>> > > > + public MapsideJoinDoFn(String inputPath, PType<Pair<K, V>> ptype) {
>> > > > + this.inputPath = inputPath;
>> > > > + this.ptype = ptype;
>> > > > + }
>> > > > +
>> > > > + private Path getCacheFilePath() {
>> > > > + try {
>> > > > + for (Path localPath :
>> > > > DistributedCache.getLocalCacheFiles(getConfiguration())) {
>> > > > + if (localPath.toString().endsWith(inputPath)) {
>> > > > + return
>> > > > localPath.makeQualified(FileSystem.getLocal(getConfiguration()));
>> > > > +
>> > > > + }
>> > > > + }
>> > > > + } catch (IOException e) {
>> > > > + throw new CrunchRuntimeException(e);
>> > > > + }
>> > > > +
>> > > > + throw new CrunchRuntimeException("Can't find local cache file
>> > > > for '" + inputPath + "'");
>> > > > + }
>> > > > +
>> > > > + @Override
>> > > > + public void initialize() {
>> > > > + super.initialize();
>> > > > +
>> > > > + ReadableSourceTarget<Pair<K, V>> sourceTarget =
>> > > > (ReadableSourceTarget<Pair<K, V>>) ptype
>> > > > + .getDefaultFileSource(getCacheFilePath());
>> > > > + Iterable<Pair<K, V>> iterable = null;
>> > > > + try {
>> > > > + iterable = sourceTarget.read(getConfiguration());
>> > > > + } catch (IOException e) {
>> > > > + throw new CrunchRuntimeException("Error reading right-side of
>> > > > map side join: ", e);
>> > > > + }
>> > > > +
>> > > > + joinMap = ArrayListMultimap.create();
>> > > > + for (Pair<K, V> joinPair : iterable) {
>> > > > + joinMap.put(joinPair.first(), joinPair.second());
>> > > > + }
>> > > > + }
>> > > > +
>> > > > + @Override
>> > > > + public void process(Pair<K, U> input, Emitter<Pair<K, Pair<U,
>> > > > V>>> emitter) {
>> > > > + K key = input.first();
>> > > > + U value = input.second();
>> > > > + for (V joinValue : joinMap.get(key)) {
>> > > > + Pair<U, V> valuePair = Pair.of(value, joinValue);
>> > > > + emitter.emit(Pair.of(key, valuePair));
>> > > > + }
>> > > > + }
>> > > > +
>> > > > + }
>> > > > +
>> > > > +}
>> > > > diff --git src/main/java/com/cloudera/crunch/types/PType.java
>> > > > src/main/java/com/cloudera/crunch/types/PType.java
>> > > > index af4ef1b..ae480aa 100644
>> > > > --- src/main/java/com/cloudera/crunch/types/PType.java
>> > > > +++ src/main/java/com/cloudera/crunch/types/PType.java
>> > > > @@ -15,6 +15,7 @@
>> > > >
>> > > > package com.cloudera.crunch.types;
>> > > >
>> > > > +import java.io.Serializable;
>> > > > import java.util.List;
>> > > >
>> > > > import org.apache.hadoop.fs.Path;
>> > > > @@ -31,7 +32,7 @@ import com.cloudera.crunch.SourceTarget;
>> > > > * {@code PCollection}.
>> > > > *
>> > > > */
>> > > > -public interface PType<T> {
>> > > > +public interface PType<T> extends Serializable {
>> > > > /**
>> > > > * Returns the Java type represented by this {@code PType}.
>> > > > */
>> > > > diff --git src/main/java/com/cloudera/crunch/types/avro/AvroType.java
>> > > > src/main/java/com/cloudera/crunch/types/avro/AvroType.java
>> > > > index 3db00c0..29af9fb 100644
>> > > > --- src/main/java/com/cloudera/crunch/types/avro/AvroType.java
>> > > > +++ src/main/java/com/cloudera/crunch/types/avro/AvroType.java
>> > > > @@ -14,6 +14,7 @@
>> > > > */
>> > > > package com.cloudera.crunch.types.avro;
>> > > >
>> > > > +import java.io.Serializable;
>> > > > import java.util.List;
>> > > >
>> > > > import org.apache.avro.Schema;
>> > > > @@ -41,7 +42,8 @@ public class AvroType<T> implements PType<T> {
>> > > > private static final Converter AVRO_CONVERTER = new AvroKeyConverter();
>> > > >
>> > > > private final Class<T> typeClass;
>> > > > - private final Schema schema;
>> > > > + private final String schemaString;
>> > > > + private transient Schema schema;
>> > > > private final MapFn baseInputMapFn;
>> > > > private final MapFn baseOutputMapFn;
>> > > > private final List<PType> subTypes;
>> > > > @@ -55,6 +57,7 @@ public class AvroType<T> implements PType<T> {
>> > > > MapFn outputMapFn, PType... ptypes) {
>> > > > this.typeClass = typeClass;
>> > > > this.schema = Preconditions.checkNotNull(schema);
>> > > > + this.schemaString = schema.toString();
>> > > > this.baseInputMapFn = inputMapFn;
>> > > > this.baseOutputMapFn = outputMapFn;
>> > > > this.subTypes = ImmutableList.<PType> builder().add(ptypes).build();
>> > > > @@ -76,6 +79,9 @@ public class AvroType<T> implements PType<T> {
>> > > > }
>> > > >
>> > > > public Schema getSchema() {
>> > > > + if (schema == null){
>> > > > + schema = new Schema.Parser().parse(schemaString);
>> > > > + }
>> > > > return schema;
>> > > > }
>> > > >
>> > > > diff --git
>> > src/test/java/com/cloudera/crunch/impl/mr/MRPipelineTest.java
>> > > > src/test/java/com/cloudera/crunch/impl/mr/MRPipelineTest.java
>> > > > new file mode 100644
>> > > > index 0000000..f265460
>> > > > --- /dev/null
>> > > > +++ src/test/java/com/cloudera/crunch/impl/mr/MRPipelineTest.java
>> > > > @@ -0,0 +1,60 @@
>> > > > +package com.cloudera.crunch.impl.mr;
>> > > > +
>> > > > +import static org.junit.Assert.assertEquals;
>> > > > +import static org.mockito.Mockito.doReturn;
>> > > > +import static org.mockito.Mockito.mock;
>> > > > +import static org.mockito.Mockito.spy;
>> > > > +import static org.mockito.Mockito.when;
>> > > > +
>> > > > +import java.io.IOException;
>> > > > +
>> > > > +import org.junit.Before;
>> > > > +import org.junit.Test;
>> > > > +
>> > > > +import com.cloudera.crunch.SourceTarget;
>> > > > +import com.cloudera.crunch.impl.mr.collect.PCollectionImpl;
>> > > > +import com.cloudera.crunch.io.ReadableSourceTarget;
>> > > > +import com.cloudera.crunch.types.avro.Avros;
>> > > > +
>> > > > +public class MRPipelineTest {
>> > > > +
>> > > > + private MRPipeline pipeline;
>> > > > +
>> > > > + @Before
>> > > > + public void setUp() throws IOException {
>> > > > + pipeline = spy(new MRPipeline(MRPipelineTest.class));
>> > > > + }
>> > > > +
>> > > > + @Test
>> > > > + public void testGetMaterializeSourceTarget_AlreadyMaterialized() {
>> > > > + PCollectionImpl<String> materializedPcollection =
>> > > > mock(PCollectionImpl.class);
>> > > > + ReadableSourceTarget<String> readableSourceTarget =
>> > > > mock(ReadableSourceTarget.class);
>> > > > +
>> > >
>> >
>> >
>> > when(materializedPcollection.getMaterializedAt()).thenReturn(readableSourceTarget);
>> > > > +
>> > > > + assertEquals(readableSourceTarget,
>> > > > pipeline.getMaterializeSourceTarget(materializedPcollection));
>> > > > + }
>> > > > +
>> > > > + @Test
>> > > > + public void
>> > >
>> >
>> >
>> > testGetMaterializeSourceTarget_NotMaterialized_HasOutput() {
>> > > > +
>> > > > + PCollectionImpl<String> pcollection = mock(PCollectionImpl.class);
>> > > > + ReadableSourceTarget<String> readableSourceTarget =
>> > > > mock(ReadableSourceTarget.class);
>> > > > + when(pcollection.getPType()).thenReturn(Avros.strings());
>> > > > +
>> > >
>> >
>> >
>> > doReturn(readableSourceTarget).when(pipeline).createIntermediateOutput(Avros.strings());
>> > > > + when(pcollection.getMaterializedAt()).thenReturn(null);
>> > > > +
>> > > > + assertEquals(readableSourceTarget,
>> > > > pipeline.getMaterializeSourceTarget(pcollection));
>> > > > + }
>> > > > +
>> > > > + @Test(expected = IllegalArgumentException.class)
>> > > > + public void
>> > >
>> >
>> >
>> > testGetMaterializeSourceTarget_NotMaterialized_NotReadableSourceTarget()
>> > > > {
>> > > > + PCollectionImpl<String> pcollection = mock(PCollectionImpl.class);
>> > > > + SourceTarget<String> nonReadableSourceTarget =
>> > >
>> >
>> >
>> > mock(SourceTarget.class);
>> > > > + when(pcollection.getPType()).thenReturn(Avros.strings());
>> > > > +
>> > >
>> >
>> >
>> > doReturn(nonReadableSourceTarget).when(pipeline).createIntermediateOutput(Avros.strings());
>> > > > + when(pcollection.getMaterializedAt()).thenReturn(null);
>> > > > +
>> > > > + pipeline.getMaterializeSourceTarget(pcollection);
>> > > > + }
>> > > > +
>> > > > +}
>> > > > diff --git
>> > >
>> >
>> >
>> > src/test/java/com/cloudera/crunch/lib/join/MapsideJoinTest.java
>> > > > src/test/java/com/cloudera/crunch/lib/join/MapsideJoinTest.java
>> > > > new file mode 100644
>> > > > index 0000000..97e0c63
>> > > > --- /dev/null
>> > > > +++ src/test/java/com/cloudera/crunch/lib/join/MapsideJoinTest.java
>> > > > @@ -0,0 +1,102 @@
>> > > > +package com.cloudera.crunch.lib.join;
>> > > > +
>> > > > +import static org.junit.Assert.assertEquals;
>> > > > +import static org.junit.Assert.assertTrue;
>> > > > +
>> > > > +import java.io.IOException;
>> > > > +import java.util.Collections;
>> > > > +import java.util.List;
>> > > > +
>> > > > +import org.junit.Test;
>> > > > +
>> > > > +import com.cloudera.crunch.FilterFn;
>> > > > +import com.cloudera.crunch.MapFn;
>> > > > +import com.cloudera.crunch.PTable;
>> > > > +import com.cloudera.crunch.Pair;
>> > > > +import com.cloudera.crunch.Pipeline;
>> > > > +import com.cloudera.crunch.impl.mem.MemPipeline;
>> > > > +import com.cloudera.crunch.impl.mr.MRPipeline;
>> > > > +import com.cloudera.crunch.impl.mr.run.CrunchRuntimeException;
>> > > > +import com.cloudera.crunch.test.FileHelper;
>> > > > +import com.cloudera.crunch.types.writable.Writables;
>> > > > +import com.google.common.collect.Lists;
>> > > > +
>> > > > +public class MapsideJoinTest {
>> > > > +
>> > > > + private static class LineSplitter extends MapFn<String,
>> > > > Pair<Integer, String>> {
>> > > > +
>> > > > + @Override
>> > > > + public Pair<Integer, String> map(String input) {
>> > > > + String[] fields = input.split("\\|");
>> > > > + return Pair.of(Integer.parseInt(fields[0]), fields[1]);
>> > > > + }
>> > > > +
>> > > > + }
>> > > > +
>> > > > + private static class NegativeFilter extends FilterFn<Pair<Integer,
>> > >
>> >
>> >
>> > String>> {
>> > > > +
>> > > > + @Override
>> > > > + public boolean accept(Pair<Integer, String> input) {
>> > > > + return false;
>> > > > + }
>> > > > +
>> > > > + }
>> > > > +
>> > > > + @Test(expected = CrunchRuntimeException.class)
>> > > > + public void testNonMapReducePipeline() {
>> > > > + runMapsideJoin(MemPipeline.getInstance());
>> > > > + }
>> > > > +
>> > > > + @Test
>> > > > + public void testMapsideJoin_RightSideIsEmpty() throws IOException {
>> > > > + MRPipeline pipeline = new MRPipeline(MapsideJoinTest.class);
>> > > > + PTable<Integer, String> customerTable = readTable(pipeline,
>> > > > "customers.txt");
>> > > > + PTable<Integer, String> orderTable = readTable(pipeline,
>> > >
>> >
>> >
>> > "orders.txt");
>> > > > +
>> > > > + PTable<Integer, String> filteredOrderTable =
>> > > > orderTable.parallelDo(new NegativeFilter(),
>> > > > + orderTable.getPTableType());
>> > > > +
>> > > > + PTable<Integer, Pair<String, String>> joined =
>> > > > MapsideJoin.join(customerTable,
>> > > > + filteredOrderTable);
>> > > > +
>> > > > + List<Pair<Integer, Pair<String, String>>> materializedJoin =
>> > > > Lists.newArrayList(joined
>> > > > + .materialize());
>> > > > +
>> > > > + assertTrue(materializedJoin.isEmpty());
>> > > > +
>> > > > + }
>> > > > +
>> > > > + @Test
>> > > > + public void testMapsideJoin() throws IOException {
>> > > > + runMapsideJoin(new MRPipeline(MapsideJoinTest.class));
>> > > > + }
>> > > > +
>> > > > + private void runMapsideJoin(Pipeline pipeline) {
>> > > > + PTable<Integer, String> customerTable = readTable(pipeline,
>> > > > "customers.txt");
>> > > > + PTable<Integer, String> orderTable = readTable(pipeline,
>> > >
>> >
>> >
>> > "orders.txt");
>> > > > +
>> > > > + PTable<Integer, Pair<String, String>> joined =
>> > > > MapsideJoin.join(customerTable, orderTable);
>> > > > +
>> > > > + List<Pair<Integer, Pair<String, String>>> expectedJoinResult =
>> > > > Lists.newArrayList();
>> > > > + expectedJoinResult.add(Pair.of(111, Pair.of("John Doe", "Corn
>> > >
>> >
>> >
>> > flakes")));
>> > > > + expectedJoinResult.add(Pair.of(222, Pair.of("Jane Doe", "Toilet
>> > >
>> >
>> >
>> > paper")));
>> > > > + expectedJoinResult.add(Pair.of(222, Pair.of("Jane Doe", "Toilet
>> > > > plunger")));
>> > > > + expectedJoinResult.add(Pair.of(333, Pair.of("Someone Else",
>> > > > "Toilet brush")));
>> > > > +
>> > > > + List<Pair<Integer, Pair<String, String>>> joinedResultList =
>> > > > Lists.newArrayList(joined
>> > > > + .materialize());
>> > > > + Collections.sort(joinedResultList);
>> > > > +
>> > > > + assertEquals(expectedJoinResult, joinedResultList);
>> > > > + }
>> > > > +
>> > > > + private static PTable<Integer, String> readTable(Pipeline pipeline,
>> > > > String filename) {
>> > > > + try {
>> > > > + return
>> > >
>> >
>> >
>> > pipeline.readTextFile(FileHelper.createTempCopyOf(filename)).parallelDo("asTable",
>> > > > + new LineSplitter(), Writables.tableOf(Writables.ints(),
>> > > > Writables.strings()));
>> > > > + } catch (IOException e) {
>> > > > + throw new RuntimeException(e);
>> > > > + }
>> > > > + }
>> > > > +
>> > > > +}
>> > > > diff --git src/test/java/com/cloudera/crunch/types/avro/AvrosTest.java
>> > > > src/test/java/com/cloudera/crunch/types/avro/AvrosTest.java
>> > > > index 74e2ad3..c6a0b46 100644
>> > > > --- src/test/java/com/cloudera/crunch/types/avro/AvrosTest.java
>> > > > +++ src/test/java/com/cloudera/crunch/types/avro/AvrosTest.java
>> > > > @@ -25,6 +25,7 @@ import org.apache.avro.Schema.Type;
>> > > > import org.apache.avro.generic.GenericData;
>> > > > import org.apache.avro.util.Utf8;
>> > > > import org.apache.hadoop.io.LongWritable;
>> > > > +import org.junit.Ignore;
>> > > > import org.junit.Test;
>> > > >
>> > > > import com.cloudera.crunch.Pair;
>> > > > @@ -103,6 +104,7 @@ public class AvrosTest {
>> > > > }
>> > > >
>> > > > @Test
>> > > > + @Ignore("This test creates an invalid schema that causes
>> > > > Schema#toString to fail")
>> > > > public void testNestedTables() throws Exception {
>> > > > PTableType<Long, Long> pll = Avros.tableOf(Avros.longs(),
>> > >
>> >
>> >
>> > Avros.longs());
>> > > > PTableType<Pair<Long, Long>, String> nest = Avros.tableOf(pll,
>> > > > Avros.strings());
>> > > > diff --git src/test/resources/customers.txt
>> > >
>> >
>> >
>> > src/test/resources/customers.txt
>> > > > new file mode 100644
>> > > > index 0000000..98f3f3d
>> > > > --- /dev/null
>> > > > +++ src/test/resources/customers.txt
>> > > > @@ -0,0 +1,4 @@
>> > > > +111|John Doe
>> > > > +222|Jane Doe
>> > > > +333|Someone Else
>> > > > +444|Has No Orders
>> > > > \ No newline at end of file
>> > > > diff --git src/test/resources/orders.txt src/test/resources/orders.txt
>> > > > new file mode 100644
>> > > > index 0000000..2f1383f
>> > > > --- /dev/null
>> > > > +++ src/test/resources/orders.txt
>> > > > @@ -0,0 +1,4 @@
>> > > > +222|Toilet plunger
>> > > > +333|Toilet brush
>> > > > +222|Toilet paper
>> > > > +111|Corn flakes
>> > > > \ No newline at end of file
>> > > >
>> > > >
>> > > >
>> > > > On Tue, Jul 3, 2012 at 10:42 AM, Christian Tzolov
>> > > > <[email protected] (mailto:[email protected])>
>> > >
>> >
>> >
>> > wrote:
>> > > > > Hi Gabriel,
>> > > > >
>> > > > > Seems like the attachment is missing.
>> > > > >
>> > > > > Cheers,
>> > > > > Chris
>> > > > >
>> > > > > On Tue, Jul 3, 2012 at 9:23 AM, Gabriel Reid <[email protected] 
>> > > > > (mailto:[email protected])(mailto:
>> > [email protected] (mailto:[email protected]))> wrote:
>> > > > >
>> > > > > > Hi guys,
>> > > > > >
>> > > > > > Attached (hopefully) is a patch for an initial implementation of
>> > map
>> > > > > > side joins. It's currently implemented as a static method in a
>> > > > >
>> > > >
>> > >
>> >
>> >
>> > class
>> > > > > > called MapsideJoin, with the same interface as the existing Join
>> > > > >
>> > > >
>> > >
>> >
>> >
>> > class
>> > > > > > (with only inner joins being implemented for now). The way it
>> > > > >
>> > > >
>> > >
>> >
>> >
>> > works is
>> > > > > > that the right-side PTable of the join is put in the distributed
>> > > > >
>> > > >
>> > >
>> >
>> >
>> > cache
>> > > > > > and then read by the join function at runtime.
>> > > > > >
>> > > > > > There's one spot that I can see for a potentially interesting
>> > > > > > optimization -- MRPipeline#run is called once for each map side
>> > > > >
>> > > >
>> > >
>> >
>> >
>> > join
>> > > > > > that is set up, but if the setup of the joins was done within
>> > > > > > MRPipeline, then we could set up multiple map side joins in
>> > > > >
>> > > >
>> > >
>> >
>> >
>> > parallel
>> > > > > > with a single call to MRPipeline#run. OTOH, a whole bunch of map
>> > > > >
>> > > >
>> > >
>> >
>> >
>> > side
>> > > > > > joins in parallel probably isn't that common of an operation.
>> > > > > >
>> > > > > > If anyone feels like taking a look at the patch, any feedback is
>> > > > > > appreciated. If nobody sees something that needs serious changes in
>> > > > > > the patch, I'll commit it.
>> > > > > >
>> > > > > > - Gabriel
>> > > > > >
>> > > > > >
>> > > > > > On Thu, Jun 21, 2012 at 9:09 AM, Gabriel Reid <
>> > [email protected] (mailto:[email protected])>
>> > > > > > wrote:
>> > > > > > > Replying to all...
>> > > > > > >
>> > > > > > > On Thu, Jun 21, 2012 at 8:40 AM, Josh Wills <[email protected] 
>> > > > > > > (mailto:[email protected])(mailto:
>> > [email protected] (mailto:[email protected]))> wrote:
>> > > > > > > >
>> > > > > > > > So there's a philosophical issue here: should Crunch ever make
>> > > > > > > > decisions about how to do something itself based on its
>> > > > > > >
>> > > > > >
>> > > > >
>> > > >
>> > >
>> >
>> >
>> > estimates of
>> > > > > > > > the size of the data sets, or should it always do exactly what
>> > > > > > >
>> > > > > >
>> > > > >
>> > > >
>> > >
>> >
>> >
>> > the
>> > > > > > > > developer indicates?
>> > > > > > > >
>> > > > > > > > I can make a case either way, but I think that no matter what,
>> > we
>> > > > > > > > would want to have explicit functions for performing a join
>> > > > > > >
>> > > > > >
>> > > > >
>> > > >
>> > >
>> >
>> >
>> > that reads
>> > > > > > > > one data set into memory, so I think we can proceed w/the
>> > > > > > > > implementation while folks weigh in on what their preferences
>> > > > > > >
>> > > > > >
>> > > > >
>> > > >
>> > >
>> >
>> >
>> > are for
>> > > > > > > > the default join() behavior (e.g., just do a reduce-side join,
>> > > > > > >
>> > > > > >
>> > > > >
>> > > >
>> > >
>> >
>> >
>> > or try
>> > > > > > > > to figure out the best join given information about the input
>> > > > > > >
>> > > > > >
>> > > > >
>> > > >
>> > >
>> >
>> >
>> > data and
>> > > > > > > > some configuration parameters.)
>> > > > > > >
>> > > > > > >
>> > > > > > >
>> > > > > > >
>> > > > > > >
>> > > > > > > I definitely agree on needing to have an explicit way to invoke
>> > one or
>> > > > > > > the other -- and in general I don't like having magic behind the
>> > > > > > > scenes to decide on behaviour (especially considering Crunch is
>> > > > > > > generally intended to be closer to the metal than Pig and Hive).
>> > > > > >
>> > > > >
>> > > >
>> > >
>> >
>> >
>> > I'm
>> > > > > > > not sure if the runtime decision is something specific to some
>> > > > > >
>> > > > >
>> > > >
>> > >
>> >
>> >
>> > of my
>> > > > > > > use cases or if it could be useful to a wider audience.
>> > > > > > >
>> > > > > > > The ability to dynamically decide at runtime whether a map side
>> > join
>> > > > > > > should be used can also easily be tacked on outside of Crunch,
>> > > > > >
>> > > > >
>> > > >
>> > >
>> >
>> >
>> > and
>> > > > > > > won't impact the underlying implementation (as you pointed out),
>> > > > > >
>> > > > >
>> > > >
>> > >
>> >
>> >
>> > so I
>> > > > > > > definitely also agree on focusing on the underlying
>> > > > > >
>> > > > >
>> > > >
>> > >
>> >
>> >
>> > implementation
>> > > > > > > first, and we can worry about the options used for exposing it
>> > > > > >
>> > > > >
>> > > >
>> > >
>> >
>> >
>> > later
>> > > > > > > on.
>> > > > > > >
>> > > > > > > - Gabriel
>>
>>
>> --
>> Director of Data Science
>> Cloudera <http://www.cloudera.com>
>> Twitter: @josh_wills <http://twitter.com/josh_wills>
>
>
>

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