Noemi Pap-Takacs created IMPALA-13191:
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Summary: Do Not Create Sort Node with Constant Ordering Expression
Key: IMPALA-13191
URL: https://issues.apache.org/jira/browse/IMPALA-13191
Project: IMPALA
Issue Type: Bug
Components: fe, Frontend
Reporter: Noemi Pap-Takacs
Rows are sorted before inserting into partitioned Iceberg tables. See
Planner.createPreDmlSort().
If we update the partitioning column of the table, the sort ordering expression
will be the partition column. If we set the new value to a constant (writing
only to 1 partition), it will be evaluated as a constant. Therefore the Sort
Node will get a constant ordering expression and works unnecessarily ordering
indistinct values.
For example:
{code:java}
create table ice_part partitioned by spec (l_discount) stored by iceberg
tblproperties('format-version'='2') as select * from tpch_parquet.lineitem
where l_linenumber=1;
explain update ice_part set l_discount=0.11 where l_discount>0.07;
{code}
The output of explain - the plan - contains a Sort Node with the following
ordering expression:
{code:java}
04:SORT
| order by: 0.11 ASC NULLS LAST
{code}
It is unnecessary to create a Sort Node to sort rows by a constant ordering
expression. Constant expressions should be omitted, just like empty ones.
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