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From Stack <st...@duboce.net>
Subject Re: Sorting keys with HFile.Writer
Date Wed, 02 Jan 2019 17:13:16 GMT
On Tue, Jan 1, 2019 at 8:42 AM Mike Thomsen <mikerthomsen@gmail.com> wrote:

> Thanks. Is there any value in me specifying the comparator?
>
>
You want to have a sort that is other than the natural hbase sort? It is
possible to specify your own comparator but you won't be able to put the
resulting hfiles under hbase for it to serve if the comparators do not
align.

S




> On Tue, Jan 1, 2019 at 9:07 AM 张铎(Duo Zhang) <palomino219@gmail.com>
> wrote:
>
> > Yes, the keys should be sorted, before passing them to HFile.Writer. The
> > way we build index for HFile is based on this assumption, that the keys
> are
> > sorted.
> >
> > Mike Thomsen <mikerthomsen@gmail.com> 于2019年1月1日周二 下午9:36写道:
> >
> > > I took some of the code from the JUnit test for setting up a HFile
> writer
> > > and it looked like it should work.
> > >
> > > Path f = new Path("/", "test-something.hfile");
> > > HFileContext context = new HFileContextBuilder()
> > >         .withBlockSize(4096)
> > >         .withIncludesTags(true)
> > >         .withCompression(Compression.Algorithm.NONE).build();
> > > HFile.Writer w = HFile.getWriterFactory(conf, cacheConf)
> > >         .withPath(FileSystem.get(conf), f)
> > >         .withFileContext(context)
> > >         .withComparator(KeyValue.COMPARATOR)
> > >         .create();
> > > //KeyValue(byte[] row, byte[] family, byte[] qualifier, long timestamp,
> > > byte[] value)
> > > Map<String, KeyValue> records = new HashMap<String, KeyValue>();
> > > for (int x = 0; x < 10000; x++) {
> > >     String uuid = UUID.randomUUID().toString();
> > >     KeyValue value = new KeyValue(uuid.getBytes(),
> "some-fam".getBytes(),
> > > "test".getBytes(), System.currentTimeMillis(), "hi".getBytes());
> > >     w.append(value);
> > > }
> > >
> > > That threw this exception:
> > >
> > > java.io.IOException: Added a key not lexically larger than previous.
> > > Current cell =
> > >
> > >
> >
> 8faf82ba-5fed-4332-9731-0ebf4d4494f9/some-fam:test/1546348994160/Put/vlen=2/seqid=0,
> > > lastCell =
> > >
> > >
> >
> e32ec727-d946-4f67-a3c6-315a27c76408/some-fam:test/1546348994160/Put/vlen=2/seqid=0
> > >     at
> > > org.apache.hadoop.hbase.io
> > > .hfile.AbstractHFileWriter.checkKey(AbstractHFileWriter.java:204)
> > >     at
> > > org.apache.hadoop.hbase.io
> > > .hfile.HFileWriterV2.append(HFileWriterV2.java:267)
> > >     at
> > > org.apache.hadoop.hbase.io
> > > .hfile.HFileWriterV3.append(HFileWriterV3.java:87)
> > >     at HFileTest.main(HFileTest.java:39)
> > >     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
> > >     at
> > >
> > >
> >
> sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
> > >     at
> > >
> > >
> >
> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
> > >     at java.lang.reflect.Method.invoke(Method.java:498)
> > >     at org.codehaus.mojo.exec.ExecJavaMojo$1.run(ExecJavaMojo.java:282)
> > >     at java.lang.Thread.run(Thread.java:748)
> > >
> > > When I manually sorted the keys, it worked fine for creating and
> closing
> > > the new HFile. Did I miss something or is this expected behavior from
> the
> > > writer? I'm testing this against HBase 1.2.9.
> > >
> > > Thanks,
> > >
> > > Mike
> > >
> >
>

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