[IMPALA-12204] Redundant codegen info of HashJoinBuilder inside a subplan

• Type: Bug
• Status: Resolved
• Priority: Critical
• Resolution: Fixed
• Fix Version/s: Impala 4.3.0
• Component/s: Backend
• Target Version: Impala 4.1.3
• Epic Color: ghx-label-8
• Assignee: Quanlong Huang
• Reporter: Quanlong Huang
• Created: 12/Jun/23 02:00
• Updated: 13/Jun/23 12:30
• Resolved: 13/Jun/23 12:30

Description

In query profile, the info strings of a hash join builder contains an ExecOption that has content like "Build Side Codegen Enabled, Hash Table Construction Codegen Enabled". When there is a HashJoin node inside a SUBPLAN node, this string could be repeated many times since the SUBPLAN node will open the right child many times. This could blow up the profile size.

I can reproduce this by the following query:

select count(*) from
  tpch_nested_parquet.customer c1,
  tpch_nested_parquet.customer c2,
  (select x.* from c1.c_orders x, c2.c_orders y
  where x.o_orderkey = y.o_orderkey) v
where c1.c_custkey = c2.c_custkey;

In the query plan, there is a HASH JOIN node inside a SUBPLAN node:

08:SUBPLAN
|  row-size=56B cardinality=1.50M
|
|--06:NESTED LOOP JOIN [CROSS JOIN]
|  |  row-size=56B cardinality=10
|  |
|  |--02:SINGULAR ROW SRC
|  |     row-size=40B cardinality=1
|  |
|  05:HASH JOIN [INNER JOIN]
|  |  hash predicates: x.o_orderkey = y.o_orderkey
|  |  row-size=16B cardinality=10
|  |
|  |--04:UNNEST [c2.c_orders y]
|  |     row-size=0B cardinality=10
|  |
|  03:UNNEST [c1.c_orders x]
|     row-size=0B cardinality=10
 

The query porfile has super long strings:

Hash Join Builder (join_node_id=5):
  ExecOption: Build Side Codegen Enabled, Hash Table Construction Codegen Enabled, Build Side Codegen Enabled, Hash Table Construction Codegen Enabled,...

Issue Links

• relates to: IMPALA-11200 Redundant additions to ExecOption field in query profile of grouping aggregator node when inside a subplan