THIS IS A TEST INSTANCE. ALL YOUR CHANGES WILL BE LOST!!!!
Apache HCatalog's behaviour can be modified through use of a few config parameters specified in jobs submitted to it. This document details all the various knobs that users have available to them, and what they accomplish.
Setup:
The properties described in this page are meant to be job-level properties set on HCat through the jobConf passed into it. This means that this page is relevant for pig users of HCatLoader/HCatStorer, or mapreduce users of HCatInputFormat/HCatOutputFormat. For a mapreduce user of HCat, these must be present as key-values in the Configuration (JobConf/Job/JobContext) used to instantiate HCatOutputFormat or HCatInputFormat. For pig users of HCatStorer, these parameters are set using the pig "set" command before instantiating a HCatLoader/HCatStorer
Storage directives:
| Property | Default | Description |
|---|---|---|
| hcat.pig.storer.external.location | Not set | An override to specify where HCatStorer will write to, defined from pig jobs, either directly by user, or by using org.apache.hive.hcatalog.pig.HCatStorerWrapper. HCat will write to this specified directory, rather than writing to the table/partition directory specified/calculatable by the metadata. This will be used in lieu of the table directory if this is a table-level write (unpartitioned table write) or in lieu of the partition directory if this is a partition-level write. This parameter is used only for non-dynamic-partitioning jobs which have multiple write destinations. |
| hcat.dynamic.partitioning.custom.pattern | Not set | For dynamic partitioning jobs, simply specifying a custom directory is not good enough, since it writes to multiple destinations, and thus, instead of a directory specification, it requires a pattern specification. That's where this parameter comes in. For example, if one had a table that was partitioned by keys country and state, with a root directory location of /apps/hive/warehouse/geo/ , then a dynamic partition write into it that writes partitions (country=US,state=CA) & (country=IN,state=KA) would create two directories: /apps/hive/warehouse/geo/country=US/state=CA/ and /apps/hive/warehouse/geo/country=IN/state=KA/ . If we wanted a different patterned location, and specified hcat.dynamic.partitioning.custom.pattern="/ext/geo/${country}-${state}", it would create the following two partition dirs: /ext/geo/US-CA and /ext/geo/IN-KA . Thus, it allows us to specify a custom dir location pattern for all the writes, and will interpolate each variable it sees when attempting to create a destination location for the partitions. See Dynamic Partitioning: External Tables for another example.
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