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From Santosh Achhra <santoshach...@gmail.com>
Subject Re: Sqoop converting timestamp field to string
Date Tue, 09 Apr 2013 17:32:18 GMT
Hi Felix,

Many thanks for your inputs. Yes using  --map-column-hive did work for me
but as you said it better to go with string columns.

Good wishes,always !

On Tue, Apr 9, 2013 at 5:49 AM, Felix GV <felix@mate1inc.com> wrote:

> Actually, what we needed to use inside of the Hive date functions to use
> our timestamp columns was this:
> from_unixtime(bigint unixtime[, string format])
> The rest of the points I brought up remain the same, IIRC...
> --
> Felix
> On Mon, Apr 8, 2013 at 5:44 PM, Felix GV <felix@mate1inc.com> wrote:
>> You can use --map-column-hive to manually specify which columns should
>> be mapped to a timestamp instead of a string. See the sqoop guide<http://sqoop.apache.org/docs/1.4.1-incubating/SqoopUserGuide.html#_importing_data_into_hive>for
more info.
>> A couple caveats:
>>    - I don't know of any way of changing the default sqoop behavior so
>>    you don't need to manually name all relevant columns in every table you're
>>    sqooping.
>>    - MySQL's date columns break when converted with this mapping
>>    (datetime and timestamp work, but not date). In order to map a MySQL date
>>    column, I had to use a custom query that converted the column to a datetime
>>    (with 00:00:00 time values) inside of MySQL so that sqoop doesn't choke on
>>    it. Obviously, this is even more annoying than having to set
>>    --map-column-hive, since it makes each sqoop command even more ad-hoc.
>>    - In the end, although all of that worked (in a very ad-hoc manner),
>>    we decided to drop it all and just go with string columns in Hive, since
>>    all (or most) of the Hive date-related functions<https://cwiki.apache.org/Hive/languagemanual-udf.html#LanguageManualUDF-DateFunctions>take
only strings as input parameters, and not timestamps, so having
>>    timestamp columns meant we had to use to_date(string timestamp) inside of
>>    each Hive date function, which made all of our queries a bit unwieldy, and
>>    also (I assume) precluded us from gaining any speed advantages from having
>>    timestamps instead of strings.
>> The last point makes me think Hive timestamps are not really ready
>> for prime time yet... They seem to be tacked on top of the system in a way
>> that's fully well integrated.
>> Please let me know if you think I'm drawing the wrong conclusions from
>> this :) ...!
>> --
>> Felix
>> On Sun, Apr 7, 2013 at 6:23 AM, Santosh Achhra <santoshachhra@gmail.com>wrote:
>>> Hello,
>>> I am using hive version 0.9 which supports timestamp fields. When I
>>> import data using sqoop using hive-import option, sqoop converts timestamp
>>> fields to string.
>>> sqoop version is Sqoop 1.4.1-cdh4.1.0
>>> Good wishes,always !
>>> Santosh

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