Vladimir Sitnikov created CALCITE-7848:
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Summary: Array.getArray() throws ClassCastException for an ARRAY
or MULTISET of INTEGER ARRAYs or MULTISETs
Key: CALCITE-7848
URL: https://issues.apache.org/jira/browse/CALCITE-7848
Project: Calcite
Issue Type: Bug
Components: core
Affects Versions: 1.42.0
Reporter: Vladimir Sitnikov
Reading a nested collection through the standard JDBC path fails when the inner
collection holds a primitive type such as INTEGER. ResultSet.getObject returns
a java.sql.Array, and calling getArray() on it throws ClassCastException.
getString on the same column returns the correct value, and the same query with
VARCHAR elements works.
Reproduced with calcite-core 1.42.0 (avatica-core 1.28.0, JDK 21.0.9) and on
main at 843f468405 (Avatica 1.29.0):
{code:java}
try (Connection c = DriverManager.getConnection("jdbc:calcite:");
ResultSet rs = c.createStatement()
.executeQuery("select array[array[1, 2], array[3, 4]]")) {
rs.next();
System.out.println(rs.getString(1));
Array array = (Array) rs.getObject(1);
System.out.println(Arrays.toString((Object[]) array.getArray()));
}
{code}
Output for three queries:
{noformat}
select array[array[1, 2], array[3, 4]]
getString: [[1, 2], [3, 4]]
getObject.getArray: java.lang.ClassCastException: class
org.apache.calcite.avatica.util.ArrayImpl cannot be cast to class
java.lang.Integer (org.apache.calcite.avatica.util.ArrayImpl is in unnamed
module of loader 'app'; java.lang.Integer is in module java.base of loader
'bootstrap')
at org.apache.calcite.avatica.util.ArrayImpl.getArray(ArrayImpl.java:115)
at org.apache.calcite.avatica.util.ArrayImpl.getArray(ArrayImpl.java:50)
select multiset[multiset[1, 2], multiset[3, 4]]
getString: [[1, 2], [3, 4]]
getObject.getArray: java.lang.ClassCastException: class
org.apache.calcite.avatica.util.ArrayImpl cannot be cast to class
java.lang.Integer (...)
select array[array['a', 'b'], array['c', 'd']]
getString: [[a, b], [c, d]]
getObject.getArray: [[a, b], [c, d]]
{noformat}
The same exception occurs on main for multiset[array[1, 2]], array[multiset[1,
2]] and multiset[multiset[array[1, 2]]].
h3. Expected
For select array[array[1, 2], array[3, 4]], getArray() returns an Object[] of
two java.sql.Array elements whose own getArray() returns int[] {1, 2} and int[]
{3, 4}. This is what the java.sql.Array contract describes for an ARRAY base
type, and it is what Calcite already returns when the inner elements are
VARCHAR.
h3. Analysis (a guess; the report above stands without it)
CalcitePrepareImpl.avaticaType passes the Rep of the component's Java class to
ColumnMetaData.array, so the metadata of INTEGER ARRAY carries
Rep.PRIMITIVE_INT. ArrayImpl.getArray of the outer collection switches on the
component type's rep, takes the PRIMITIVE_INT branch, and casts each inner
ArrayImpl to Integer. VARCHAR maps to Rep.STRING, falls through to the Object[]
branch, and works. CALCITE-910 (commit 4000edd8e6, 2015) introduced the
component-based rep; before it the rep came from the collection's own class.
Passing Rep.ARRAY or Rep.MULTISET, as the Avatica test for CALCITE-3557
(ArrayAccessorTest.resultSetFromMultisetArray) does, makes all the queries
above return nested java.sql.Array values, and the core test suite passes.
h3. Related
CALCITE-3557 fixed the ClassCastException on the getString path (Avatica
1.23.0); this report is about getObject().getArray(), which still fails.
CALCITE-1335 is about getArray() returning internal representations of DATE and
TIMESTAMP, not this exception.
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