Danny Chan created CALCITE-2928:
-----------------------------------
Summary: Make UDF lookup default to case insensitive
Key: CALCITE-2928
URL: https://issues.apache.org/jira/browse/CALCITE-2928
Project: Calcite
Issue Type: Improvement
Components: core
Affects Versions: 1.19.0
Reporter: Danny Chan
Assignee: Danny Chan
Fix For: 1.19.0
Now for Calcite, we make default parser config unquotedCasing to
Lex.ORACLE.unquotedCasing(to uppercase)[1], and caseSensitive to
Lex.ORACLE.caseSensitive(case sensitive true).
So if we have a UDAF named my_func and query with sql like:
{code:java}
select f0, my_func(f1) from table1 group by f0;
{code}
We would got a unparsed sql:
{code:java}
SELECT F0, MY_FUNC(F1) FROM TABLE1 GROUP BY F0;
{code}
For CalciteCatalogReader we hard code the function look up to case sensitive
true[2],
For ListSqlOperatorTable we make the operator name lookup case sensitive
true[3].
For ReflectiveSqlOperatorTable, we make built-in operators
case-insensitively[4].
For most of the cases, we use ListSqlOperatorTable to register our UDFs[5]
chained with SqlStdOperatorTable(which composite a ChainedSqlOperatorTable),
which finally passed to CalciteCatalogReader for validation.
So there are some questions i have:
1. Why we make built-in operators look up case-insensitively while
ListSqlOperatorTable(for UDFs) case-sensitively, with default unquotedCasing of
TO_UPPERCASE.
2. What is the usage of CalciteCatalogReader#lookupOperatorOverloads i only saw
it used in a unit test LookupOperatorOverloadsTest.
It seems that make UDF look up case-sensitively does not make any sense, users
will never distinguish their function with just word cases. And i checked also
MYSQL, ORACLE, POSTGRES, their UDFs are all registered case-insensitively.
[1]
https://github.com/apache/calcite/blob/ffca956be03a99cd11e440d652b09674aaa727e6/core/src/main/java/org/apache/calcite/sql/parser/SqlParser.java#L231
[2]
https://github.com/apache/calcite/blob/ffca956be03a99cd11e440d652b09674aaa727e6/core/src/main/java/org/apache/calcite/prepare/CalciteCatalogReader.java#L166
[3]
https://github.com/apache/calcite/blob/ffca956be03a99cd11e440d652b09674aaa727e6/core/src/main/java/org/apache/calcite/sql/util/ListSqlOperatorTable.java#L63
[4]
https://github.com/apache/calcite/blob/ffca956be03a99cd11e440d652b09674aaa727e6/core/src/main/java/org/apache/calcite/sql/util/ReflectiveSqlOperatorTable.java#L103
[5]
https://github.com/apache/calcite/blob/ffca956be03a99cd11e440d652b09674aaa727e6/core/src/test/java/org/apache/calcite/test/MockSqlOperatorTable.java#L46
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