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https://issues.apache.org/jira/browse/CALCITE-1882?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16106042#comment-16106042
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yuqi commented on CALCITE-1882:
-------------------------------
The reason that causes this problem is that in parser phase, the parser
directly convert 'SUM' to SqlSumAggFunction not SqlUnresolvedFuntion by name
and at this time user-defined aggregate function has not been registered. this
should be done in the validate phase as at this time converting 'Sum' to
SqlSumAggFunction will cause calcite filters all function that is not
SqlKind.SUM like user-defined aggregate funcion. Converting in the early phase
may accelerate the validate phase later, but it will omit the user-defined
aggregate function, which will lead validator can't find function.
My resolution:
Method of createCall in SqlAbstractParserImpl.java directly returns
SqlUnresolvedFunction not a clear specific function like SqlSumAggFunction. But
if do like this, hundreds of test case fail as createCall has changed and sql
changed greatly after parser. this is quite troublesome.
Is that OK? advice is appreciate, thanks
> Can't obtain the user defined aggregate function such as sum,avg by calcite
> ---------------------------------------------------------------------------
>
> Key: CALCITE-1882
> URL: https://issues.apache.org/jira/browse/CALCITE-1882
> Project: Calcite
> Issue Type: Bug
> Affects Versions: 1.12.0
> Reporter: yuemeng
> Assignee: yuemeng
> Priority: Critical
>
> If we want to register a sum or avg aggregate function to deal with different
> data type such as sum(double) ,we implement a SqlUserDefinedAggFunction and
> register with name sum,but when we execute a sql like:
> {code}
> select id,sum(payment) from table test group by id
> {code}
> in fact,it always give the SqlSumAggFunction function which builtin by
> calcite,never find the exactly function which we register by ourself.
> During sql parse process,method createCall in SqlAbstractParserImpl will be
> called,
> {code}
> protected SqlCall createCall(
> SqlIdentifier funName,
> SqlParserPos pos,
> SqlFunctionCategory funcType,
> SqlLiteral functionQualifier,
> SqlNode[] operands) {
> SqlOperator fun = null;
> // First, try a half-hearted resolution as a builtin function.
> // If we find one, use it; this will guarantee that we
> // preserve the correct syntax (i.e. don't quote builtin function
> /// name when regenerating SQL).
> if (funName.isSimple()) {
> final List<SqlOperator> list = Lists.newArrayList();
> opTab.lookupOperatorOverloads(funName, funcType, SqlSyntax.FUNCTION,
> list);//we lookup in SqlStdOperatorTable,and always find buidin function for
> sum ,avg .eg
> if (list.size() == 1) {
> fun = list.get(0);
> }
> }
> // Otherwise, just create a placeholder function. Later, during
> // validation, it will be resolved into a real function reference.
> if (fun == null) {
> fun = new SqlUnresolvedFunction(funName, null, null, null, null,
> funcType);
> }
> return fun.createCall(functionQualifier, pos, operands);
> }
> {code}
> but the problem will be appear in deriveType,because of we get the
> SqlSumAggFunction previously,and the sqlKind of SqlSumAggFunction is AVG,but
> the sqlKind of sql user defined agg function (sum) which we register by
> ourself is OTHER_FUNCTION,so it filter out our sum function.
> {code}
> private static Iterator<SqlOperator>
> filterOperatorRoutinesByKind(Iterator<SqlOperator> routines,
> final SqlKind sqlKind) {
> return Iterators.filter(routines,
> new PredicateImpl<SqlOperator>() {
> public boolean test(SqlOperator input) {
> return input.getKind() == sqlKind;
> }
> });
> }
> {code}
> that cause we never obtain sum function which registered by user .
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