Mihai Budiu created CALCITE-6403:
------------------------------------
Summary: Rule AGGREGATE_EXPAND_DISTINCT_AGGREGATES is unsound
Key: CALCITE-6403
URL: https://issues.apache.org/jira/browse/CALCITE-6403
Project: Calcite
Issue Type: Bug
Components: core
Affects Versions: 1.37.0
Reporter: Mihai Budiu
Here is a simple SQL program that operates on a collection with no input rows:
{code:sql}
SELECT COUNT(*), COUNT(DISTINCT COL1) FROM T WHERE false"
{code}
The rewrite rule expands this into:
{code}
LogicalProject(EXPR$0=[CAST($0):BIGINT NOT NULL], EXPR$1=[$1]), id = 39
LogicalAggregate(group=[{}], EXPR$0=[MIN($1) FILTER $3],
EXPR$1=[COUNT($0) FILTER $2]), id = 37
LogicalProject(COL1=[$0], EXPR$0=[$1], $g_0=[=($2, 0)], $g_1=[=($2,
1)]), id = 35
LogicalAggregate(group=[{0}], groups=[[{0}, {}]], EXPR$0=[COUNT()],
$g=[GROUPING($0)]), id = 30
LogicalValues(tuples=[[]]), id = 22
{code}
Notice that there is an inner group-by aggregate that produces an empty set,
and an outer aggregation that uses MIN. MIN for an empty collection is NULL,
whereas the original query should have produced 0.
--
This message was sent by Atlassian Jira
(v8.20.10#820010)
