For question 5, this link [1] probably explains why 31 is used:
[1] http://stackoverflow.com/questions/299304/why-does-javas-hashcode-in-string-use-31-as-a-multiplier On Tue, Sep 22, 2015 at 10:05 AM, Abdel Hakim Deneche <adene...@maprtech.com> wrote: > Question 3: > I would assume getWriterOperatorType() has a similar meaning to > getReaderOperatorType() but it's not used anywhere in Drill. That would > explain why JsonFormatPlugin throws an UnsupportedOperationException > > Question 4: > supportsPushDown() is about "projection" push down and not filter push down > > Question 5: > I would say, purely random. > > On Fri, Sep 18, 2015 at 11:48 AM, Edmon Begoli <ebeg...@gmail.com> wrote: > >> Thanks, Abdel. >> I will use your answers to guide my development, but I will also contribute >> them back as a javadoc. >> >> On Fri, Sep 18, 2015 at 2:39 PM, Abdel Hakim Deneche < >> adene...@maprtech.com> >> wrote: >> >> > Question 2: >> > to my knowledge (what I've found digging through the code). Each Operator >> > has a unique OperatorType that is used when writing the operator's stats >> in >> > the profile. So in this case, Each FormatPlugin implementation should >> have >> > a corresponding unique OperatorType added to CoreOperatorType. >> > >> > I will get back to you after I get more information about the remaining >> > questions. >> > >> > Thanks >> > >> > On Thu, Sep 17, 2015 at 8:14 PM, Edmon Begoli <ebeg...@gmail.com> wrote: >> > >> > > Hello all, >> > > >> > > Could some please with answering my questions 2-5 below? >> > > >> > > Thank you, >> > > Edmon >> > > >> > > On Wednesday, September 16, 2015, Edmon Begoli <ebeg...@gmail.com> >> > wrote: >> > > >> > > > I am studying the JSON Storage plugin. >> > > > >> > > > Can someone please answer what is the meaning (or intent) of the >> > > following >> > > > methods: >> > > > >> > > > # Question 1: >> > > > # This is from inside the getter for RecordWriter. What is >> major/minor >> > > > fragment id? >> > > > String fragmentId = String.format("%d_%d", >> handle.getMajorFragmentId(), >> > > > handle.getMinorFragmentId()); >> > > > >> > > > >> > > > # Question 2: >> > > > # Speficially, what is Operator Type, and what is JSON specific about >> > it? >> > > > public int getReaderOperatorType() { >> > > > return CoreOperatorType.JSON_SUB_SCAN_VALUE; >> > > > } >> > > > >> > > > # Question 3: >> > > > # same, but for writer >> > > > @Override >> > > > public int getWriterOperatorType() { >> > > > throw new UnsupportedOperationException(); >> > > > } >> > > > >> > > > # Question 4: >> > > > # I generally understand the concept of predicate pushdown, but is >> this >> > > > about predicate push down or something else? >> > > > # How does one implement a push down for storage format? >> > > > @Override >> > > > public boolean supportsPushDown() { >> > > > >> > > > # Question 5: >> > > > # Is this int value of 31 purely randomly selected, or is there an >> > index >> > > > somewhere? >> > > > @Override >> > > > public int hashCode() { >> > > > return 31; >> > > > } >> > > > >> > > > >> > > > >> > > > >> > > >> > >> > >> > >> > -- >> > >> > Abdelhakim Deneche >> > >> > Software Engineer >> > >> > <http://www.mapr.com/> >> > >> > >> > Now Available - Free Hadoop On-Demand Training >> > < >> > >> http://www.mapr.com/training?utm_source=Email&utm_medium=Signature&utm_campaign=Free%20available >> > > >> > >> > > > > -- > > Abdelhakim Deneche > > Software Engineer > > <http://www.mapr.com/> > > > Now Available - Free Hadoop On-Demand Training > <http://www.mapr.com/training?utm_source=Email&utm_medium=Signature&utm_campaign=Free%20available>
