Github user amansinha100 commented on a diff in the pull request:
https://github.com/apache/drill/pull/397#discussion_r54689413
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/expr/fn/DrillFunctionRegistry.java
---
@@ -92,38 +94,110 @@ public DrillFunctionRegistry(ScanResult classpathScan)
{
}
public int size(){
- return methods.size();
+ return registeredFunctions.size();
}
/** Returns functions with given name. Function name is case
insensitive. */
public List<DrillFuncHolder> getMethods(String name) {
- return this.methods.get(name.toLowerCase());
+ return this.registeredFunctions.get(name.toLowerCase());
+ }
+
+ public Collection<DrillFuncHolder> getAllMethods() {
+ return
Collections.unmodifiableCollection(registeredFunctions.values());
}
public void register(DrillOperatorTable operatorTable) {
- SqlOperator op;
- for (Entry<String, Collection<DrillFuncHolder>> function :
methods.asMap().entrySet()) {
- Set<Integer> argCounts = Sets.newHashSet();
- String name = function.getKey().toUpperCase();
+ for (Entry<String, Collection<DrillFuncHolder>> function :
registeredFunctions.asMap().entrySet()) {
+ final ArrayListMultimap<Pair<Integer, Integer>, DrillFuncHolder>
functions = ArrayListMultimap.create();
+ final ArrayListMultimap<Integer, DrillFuncHolder> aggregateFunctions
= ArrayListMultimap.create();
+ final String name = function.getKey().toUpperCase();
+ boolean isDeterministic = true;
for (DrillFuncHolder func : function.getValue()) {
- if (argCounts.add(func.getParamCount())) {
- if (func.isAggregating()) {
- op = new DrillSqlAggOperator(name, func.getParamCount());
- } else {
- boolean isDeterministic;
- // prevent Drill from folding constant functions with types
that cannot be materialized
- // into literals
- if
(DrillConstExecutor.NON_REDUCIBLE_TYPES.contains(func.getReturnType().getMinorType()))
{
- isDeterministic = false;
- } else {
- isDeterministic = func.isDeterministic();
- }
- op = new DrillSqlOperator(name, func.getParamCount(),
func.getReturnType(), isDeterministic);
- }
- operatorTable.add(function.getKey(), op);
+ final int paramCount = func.getParamCount();
+ if(func.isAggregating()) {
+ aggregateFunctions.put(paramCount, func);
+ } else {
+ final Pair<Integer, Integer> argNumerRange =
getArgNumerRange(name, func);
+ functions.put(argNumerRange, func);
}
+
+ if(!func.isDeterministic()) {
+ isDeterministic = false;
+ }
+ }
+ for (Entry<Pair<Integer, Integer>, Collection<DrillFuncHolder>>
entry : functions.asMap().entrySet()) {
+ final DrillSqlOperator drillSqlOperator;
+ final Pair<Integer, Integer> range = entry.getKey();
+ final int max = range.getRight();
+ final int min = range.getLeft();
+ drillSqlOperator = new DrillSqlOperator(
+ name,
+ Lists.newArrayList(entry.getValue()),
+ min,
+ max,
+ isDeterministic);
+ operatorTable.add(name, drillSqlOperator);
+ }
+ for (Entry<Integer, Collection<DrillFuncHolder>> entry :
aggregateFunctions.asMap().entrySet()) {
+ operatorTable.add(name, new DrillSqlAggOperator(name,
Lists.newArrayList(entry.getValue()), entry.getKey()));
}
}
+
+ registerCalcitePlaceHolderFunction(operatorTable);
+ }
+
+ /**
+ * These {@link DrillSqlOperator} merely act as a placeholder so that
Calcite
+ * allows convert_to(), convert_from(), flatten(), date_part() functions
in SQL.
+ */
+ private void registerCalcitePlaceHolderFunction(DrillOperatorTable
operatorTable) {
+ final String convert_to = "CONVERT_TO";
+ final String convert_from = "CONVERT_FROM";
+ final String flatten = "FLATTEN";
+ final String date_part = "DATE_PART";
+
+ operatorTable.add(convert_to,
+ new DrillSqlOperator(convert_to,
+ 2,
+ true));
+ operatorTable.add(convert_from,
+ new DrillSqlOperator(convert_from,
+ 2,
+ true));
+ operatorTable.add(flatten,
+ new DrillSqlOperator(flatten,
+ 1,
+ true));
+ operatorTable.add(date_part,
+ new DrillSqlOperator(date_part,
+ 2,
+ true));
}
+ private Pair<Integer, Integer> getArgNumerRange(final String name, final
DrillFuncHolder func) {
+ switch(name.toUpperCase()) {
+ case "CONCAT":
--- End diff --
Similar to the previous comment, it would be preferable to not have switch
statements with lots of cases (the number of such functions that need to be
handled here could keep growing).
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