Specified functions in the partitioning predicates should not generate a M/R job.

For certain situations specifying which functions should be evaluated once would help to make syntax simpler to avoid launching M/R jobs.

Example:

# myhql.time=`date "+%s"` -> constant
# counting rows from the last 30 days generates a M/R job using all the partitions
$ hive -hiveconf myhql.time=`date "+%s"` -e "SELECT COUNT(*) FROM mybigtable WHERE mypartition >= from_unixtime(\${hiveconf:myhql.time}-2592000,'yyyy-MM-dd');

Suggested feature:

# will scan only the right partitions
$ hive -hiveconf hive.partition.evaluateonce=unix_timestamp -e "SELECT COUNT(*) FROM mybigtable WHERE mypartition >= from_unixtime(unix_timestamp()-2592000,'yyyy-MM-dd');