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https://issues.apache.org/jira/browse/HIVE-493?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12730952#action_12730952
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Prasad Chakka commented on HIVE-493:
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bq. hive --service compact --table tablea
this would be easiest for users but not extensible in the sense that users will
not be able to do more things. eventually users start asking for options to do
such things as not rebuild indexes but just drop them or not compact if the
number files is small or total size is small etc. this requires lot more effort
from developers to provide such options. it may be better to provide ways to
script these things using python. may be we can provide basic tools that does
not require lot of Hive internal knowledge. there is a JIRA open to create and
execute Hive queries natively in Python. We should extend such API to do these
kind of tasks better.
i am not sure how you can use queries like 'select columns from table where
tablename='tablea' ' for your usecase without a PLSQL kind of support from
HiveQL.
> automatically infer existing partitions of table from HDFS files.
> -----------------------------------------------------------------
>
> Key: HIVE-493
> URL: https://issues.apache.org/jira/browse/HIVE-493
> Project: Hadoop Hive
> Issue Type: New Feature
> Components: Metastore, Query Processor
> Affects Versions: 0.3.0, 0.3.1, 0.4.0
> Reporter: Prasad Chakka
>
> Initially partition list for a table is inferred from HDFS directory
> structure instead of looking into metastore (partitions are created using
> 'alter table ... add partition'). but this automatic inferring was removed to
> favor the later approach during checking-in metastore checker feature and
> also to facilitate external partitions.
> Joydeep and Frederick mentioned that it would simple for users to create the
> HDFS directory and let Hive infer rather than explicitly add a partition. But
> doing that raises following...
> 1) External partitions -- so we have to mix both approaches and partition
> list is merged list of inferred partitions and registered partitions. and
> duplicates have to be resolved.
> 2) Partition level schemas can't supported. Which schema to chose for the
> inferred partitions? the table schema when the inferred partition is created
> or the latest tale schema? how do we know the table schema when the inferred
> partitions is created?
> 3) If partitions have to be registered the partitions can be disabled without
> actually deleting the data. this feature is not supported and may not be that
> useful but nevertheless this can't be supported with inferred partitions
> 4) Indexes are being added. So if partitions are not registered then indexes
> for such partitions can not be maintained automatically.
> I would like to know what is the general thinking about this among users of
> Hive. If inferred partitions are preferred then can we live with restricted
> functionality that this imposes?
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