FAQ
Is there an equivalent to the Cascalog predicate operator "#:>" in
JCascalog? I've got a source coming from an RDBMS that has 32 fields and I
only care about 9 of them. In Cascalog I'd just use the handy "#:>"
predicate operator. Does JCascalog have the same functionality?

Thanks,

Dave

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  • PK at Jun 12, 2013 at 8:00 pm
    How about not reading the column altogether by not defining it in the
    Scheme of the source tap for the database table?
    On Tuesday, June 11, 2013 5:34:19 PM UTC-7, David Kincaid wrote:

    Is there an equivalent to the Cascalog predicate operator "#:>" in
    JCascalog? I've got a source coming from an RDBMS that has 32 fields and I
    only care about 9 of them. In Cascalog I'd just use the handy "#:>"
    predicate operator. Does JCascalog have the same functionality?

    Thanks,

    Dave
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  • David Kincaid at Jun 13, 2013 at 4:42 pm
    We are using Sqoop to import the records into HDFS. It's writing
    tab-delimited files. So the scheme we're using is the TextDelimited scheme.
    Is there an option there to have it only read some of the fields?
    On Wednesday, June 12, 2013 4:00:04 PM UTC-4, PK wrote:

    How about not reading the column altogether by not defining it in the
    Scheme of the source tap for the database table?
    On Tuesday, June 11, 2013 5:34:19 PM UTC-7, David Kincaid wrote:

    Is there an equivalent to the Cascalog predicate operator "#:>" in
    JCascalog? I've got a source coming from an RDBMS that has 32 fields and I
    only care about 9 of them. In Cascalog I'd just use the handy "#:>"
    predicate operator. Does JCascalog have the same functionality?

    Thanks,

    Dave
    --
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  • PK at Jun 13, 2013 at 5:51 pm
    You can replace the field names that you do not want to read with
    underscores :
    https://github.com/nathanmarz/cascalog/wiki/Methods-for-handling-wide-sources

    On Thursday, June 13, 2013 9:42:13 AM UTC-7, David Kincaid wrote:

    We are using Sqoop to import the records into HDFS. It's writing
    tab-delimited files. So the scheme we're using is the TextDelimited scheme.
    Is there an option there to have it only read some of the fields?
    On Wednesday, June 12, 2013 4:00:04 PM UTC-4, PK wrote:

    How about not reading the column altogether by not defining it in the
    Scheme of the source tap for the database table?
    On Tuesday, June 11, 2013 5:34:19 PM UTC-7, David Kincaid wrote:

    Is there an equivalent to the Cascalog predicate operator "#:>" in
    JCascalog? I've got a source coming from an RDBMS that has 32 fields and I
    only care about 9 of them. In Cascalog I'd just use the handy "#:>"
    predicate operator. Does JCascalog have the same functionality?

    Thanks,

    Dave
    --
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  • PK at Jun 13, 2013 at 5:52 pm
    In JCascalog it will be the same as well :
    https://github.com/nathanmarz/cascalog/wiki/JCascalog

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  • David Kincaid at Jun 13, 2013 at 6:35 pm
    Yes. I was hoping to be able to use something like the #:> operator that
    Cascalog has.

    BTW, there is a problem with the underscores:
    https://groups.google.com/forum/?fromgroups=#!topic/cascalog-user/zfZ86T16gQU


    On Thursday, June 13, 2013 1:51:11 PM UTC-4, PK wrote:

    You can replace the field names that you do not want to read with
    underscores :
    https://github.com/nathanmarz/cascalog/wiki/Methods-for-handling-wide-sources
    On Thursday, June 13, 2013 9:42:13 AM UTC-7, David Kincaid wrote:

    We are using Sqoop to import the records into HDFS. It's writing
    tab-delimited files. So the scheme we're using is the TextDelimited scheme.
    Is there an option there to have it only read some of the fields?
    On Wednesday, June 12, 2013 4:00:04 PM UTC-4, PK wrote:

    How about not reading the column altogether by not defining it in the
    Scheme of the source tap for the database table?
    On Tuesday, June 11, 2013 5:34:19 PM UTC-7, David Kincaid wrote:

    Is there an equivalent to the Cascalog predicate operator "#:>" in
    JCascalog? I've got a source coming from an RDBMS that has 32 fields and I
    only care about 9 of them. In Cascalog I'd just use the handy "#:>"
    predicate operator. Does JCascalog have the same functionality?

    Thanks,

    Dave
    --
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  • Jeroen van Dijk at Jun 13, 2013 at 7:15 pm
    Regarding using Sqoop to import records into HDFS, you can also export to
    the Avro format and use https://github.com/bixolabs/cascading.avro to read
    it. That's what I've done before.

    The advantage is that if you have fields like timestamps etc. you don't
    have to deal with possibly complex or error prone conversions.

    On Thu, Jun 13, 2013 at 8:35 PM, David Kincaid wrote:

    Yes. I was hoping to be able to use something like the #:> operator that
    Cascalog has.

    BTW, there is a problem with the underscores:
    https://groups.google.com/forum/?fromgroups=#!topic/cascalog-user/zfZ86T16gQU


    On Thursday, June 13, 2013 1:51:11 PM UTC-4, PK wrote:

    You can replace the field names that you do not want to read with
    underscores : https://github.com/nathanmarz/**cascalog/wiki/Methods-for-*
    *handling-wide-sources<https://github.com/nathanmarz/cascalog/wiki/Methods-for-handling-wide-sources>
    On Thursday, June 13, 2013 9:42:13 AM UTC-7, David Kincaid wrote:

    We are using Sqoop to import the records into HDFS. It's writing
    tab-delimited files. So the scheme we're using is the TextDelimited scheme.
    Is there an option there to have it only read some of the fields?
    On Wednesday, June 12, 2013 4:00:04 PM UTC-4, PK wrote:

    How about not reading the column altogether by not defining it in the
    Scheme of the source tap for the database table?
    On Tuesday, June 11, 2013 5:34:19 PM UTC-7, David Kincaid wrote:

    Is there an equivalent to the Cascalog predicate operator "#:>" in
    JCascalog? I've got a source coming from an RDBMS that has 32 fields and I
    only care about 9 of them. In Cascalog I'd just use the handy "#:>"
    predicate operator. Does JCascalog have the same functionality?

    Thanks,

    Dave
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groupcascalog-user @
categoriesclojure, hadoop
postedJun 12, '13 at 12:34a
activeJun 13, '13 at 7:15p
posts7
users3
websiteclojure.org
irc#clojure

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