[jira] [Created] (HIVE-7324) CBO: provide a mechanism to test CBO features based on table stats only (w/o table data)

["Harish Butani (JIRA)" <ji...@apache.org>]

Harish Butani created HIVE-7324:
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             Summary: CBO: provide a mechanism to test CBO features based on table stats only (w/o table data)
                 Key: HIVE-7324
                 URL: https://issues.apache.org/jira/browse/HIVE-7324
             Project: Hive
          Issue Type: Sub-task
            Reporter: Harish Butani
            Assignee: Harish Butani


Since lot of the CBO work is focused on planning, it will be nice to be able to run explain query to test CBO features. TPCDS has a rich enough schema and query set. So the patch loads a dump TPCDS(Scale 10000) stats.

1. TestCBO shows a way to load stats from a dump and run explain on a tpcds query. The output is currently dumped to Sys.out. This can be improved by hooking to QTestUtil, but hopefully this is a good start.

2. Uncovered couple of issues in the process of testing this:
a) PartitionPruner fails on 'true' constants. For e.g. you will get an error for 
{code}
select * from t where partCol < 100 and true
{code}
This gets exposed because the predicates coming out of Optiq can contain 'true' predicates.
b) OpTraitsRulesProcFactory:checkBucketedTable checks that number of files = numBuckets. This fails because there are no dataFiles. So I have altered it to catch exceptions and assume bucketMapJoinConvertible = false if an exception is encountered here.
Uploading with these changes in this patch for now. Will carve them out as separate patches.

[~ashutoshc], [~hagleitn] can you please take a look. 





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