There are a few scenarios where we warn against inconsistencies. Using a character column as a split by column, using complex queries with split by column that can potentially generate incorrect data in each of the mappers than what is intended.If you use -m 1 option, then you don't have the inconsistency issues.VenkatCONFIDENTIALITY NOTICEOn Thu, Sep 18, 2014 at 2:40 PM, pratik khadloya <email@example.com> wrote:Am not facing any problem. Am checking to see what are the reservations against not supporting complex joins with OR conditions.I would like to know when it could create a problem and would the problem be solvable by using a "view" or limiting the number of mappers to just 1.I would like to know if the problem if any is due to the parallelism which comes with increasing the number of mappers?~PratikOn Thu, Sep 18, 2014 at 1:23 PM, Sambit Tripathy (RBEI/PJ-NBS) <Sambit.Tripathy@in.bosch.com> wrote:
Are you facing a problem or trying to make a recommendation?
The sqoop docs say:
The facility of using free-form query in the current version of Sqoop is limited to simple queries where there are no ambiguous projections and no
ORconditions in the
WHEREclause. Use of complex queries such as queries that have sub-queries or joins leading to ambiguous projections can lead to unexpected results.
Does anyone know why such is case is not supported and can it be avoided by:
a) Using only 1 mapper
b) Creating a view out of the complex query
I have tested a hive textfile import for a very complex query and verified the data and it seems to be correct. I checked the number of words, number of lines and file sizes of the dump from mysql vs the text file imported onto hdfs by sqoop.
My query does have OR conditions. I have attached an obfuscated version of the query, and that screenprint is still 1/2 of the complete query.
Any info on this will be helpful.
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