[HIVE-21289] Expect EQ and LIKE to Generate the Identical Explain Plans

• Type: Improvement
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Affects Version/s: 2.3.4
• Component/s: CBO, Logical Optimizer
• Assignee: Unassigned
• Reporter: David Mollitor
• Created: 19/Feb/19 15:30
• Updated: 19/Mar/20 14:07

Description

I generated some test data with the UUID function.

explain select * from test_like where a like 'abce6254-d437-426b-8873-2cbc153ddfbc';
explain select * from test_like where a = 'abce6254-d437-426b-8873-2cbc153ddfbc';

Explain
STAGE DEPENDENCIES:
  Stage-1 is a root stage
  Stage-0 depends on stages: Stage-1

STAGE PLANS:
  Stage: Stage-1
    Map Reduce
      Map Operator Tree:
          TableScan
            alias: test_like
            filterExpr: (a like 'abce6254-d437-426b-8873-2cbc153ddfbc') (type: boolean)
            Statistics: Num rows: 262144 Data size: 9437184 Basic stats: COMPLETE Column stats: NONE
            Filter Operator
              predicate: (a like 'abce6254-d437-426b-8873-2cbc153ddfbc') (type: boolean)
              Statistics: Num rows: 131072 Data size: 4718592 Basic stats: COMPLETE Column stats: NONE
              Select Operator
                expressions: a (type: string)
                outputColumnNames: _col0
                Statistics: Num rows: 131072 Data size: 4718592 Basic stats: COMPLETE Column stats: NONE
                File Output Operator
                  compressed: false
                  Statistics: Num rows: 131072 Data size: 4718592 Basic stats: COMPLETE Column stats: NONE
                  table:
                      input format: org.apache.hadoop.mapred.TextInputFormat
                      output format: org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat
                      serde: org.apache.hadoop.hive.serde2.lazy.LazySimpleSerDe

  Stage: Stage-0
    Fetch Operator
      limit: -1
      Processor Tree:
        ListSink

Explain
STAGE DEPENDENCIES:
  Stage-1 is a root stage
  Stage-0 depends on stages: Stage-1

STAGE PLANS:
  Stage: Stage-1
    Map Reduce
      Map Operator Tree:
          TableScan
            alias: test_like
            filterExpr: (a = 'abce6254-d437-426b-8873-2cbc153ddfbc') (type: boolean)
            Statistics: Num rows: 262144 Data size: 9437184 Basic stats: COMPLETE Column stats: NONE
            Filter Operator
              predicate: (a = 'abce6254-d437-426b-8873-2cbc153ddfbc') (type: boolean)
              Statistics: Num rows: 131072 Data size: 4718592 Basic stats: COMPLETE Column stats: NONE
              Select Operator
                expressions: 'abce6254-d437-426b-8873-2cbc153ddfbc' (type: string)
                outputColumnNames: _col0
                Statistics: Num rows: 131072 Data size: 4718592 Basic stats: COMPLETE Column stats: NONE
                File Output Operator
                  compressed: false
                  Statistics: Num rows: 131072 Data size: 4718592 Basic stats: COMPLETE Column stats: NONE
                  table:
                      input format: org.apache.hadoop.mapred.TextInputFormat
                      output format: org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat
                      serde: org.apache.hadoop.hive.serde2.lazy.LazySimpleSerDe

  Stage: Stage-0
    Fetch Operator
      limit: -1
      Processor Tree:
        ListSink

They may be the same under the covers, but I would expect the EXPLAIN plan to be exactly the same.