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https://issues.apache.org/jira/browse/CALCITE-2928?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16804703#comment-16804703
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Julian Hyde commented on CALCITE-2928:
--------------------------------------
Reviewing the PR, here are a few initial reactions:
* I don't think you need to add {{boolean caseSensitive}} to
{{CalciteCatalogReader}} methods such as {{getFunctionsFrom}}.
{{CalciteCatalogReader}} has a {{nameMatcher}} field that encapsulates
case-sensitivity policy.
* Probably SqlOperator.isName does not need a {{boolean caseSensitive}}
parameter because by that point you have got a case-sensitive name to lookup
with.
* {{caseSensitive}} should not be a property of the SqlOperatorTable - it is a
property of the session that is looking up operators in the table.
* Probably SqlUtil.lookupRoutine does not need a caseSensitive because it is
only called internally - note that the two places that call it use
SqlFunction.getNameAsId(), in other words, the function has already been
resolved, it's just looking itself up again
* In most places where you do need caseSensitive you should instead pass a
SqlNameMatcher.
Next, I'm going to try running your test and see how many changes I can back
out without things breaking.
> 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
> Priority: Major
> Labels: pull-request-available
> Fix For: 1.20.0
>
> Time Spent: 10m
> Remaining Estimate: 0h
>
> 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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