Github user jacques-n commented on a diff in the pull request: https://github.com/apache/drill/pull/397#discussion_r54763735 --- 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": + return Pair.of(1, Integer.MAX_VALUE); + + // Drill does not have a FunctionTemplate for the lpad/rpad with two arguments. + // It relies on DrillOptiq.java to add a third dummy argument to be acceptable + // by the FunctionTemplate in StringFunctions.java + case "LPAD": + case "RPAD": + return Pair.of(2, 3); + + // Similar to the reason above, DrillOptiq.java is used for rewritting + case "LTRIM": + case "RTRIM": + case "BTRIM": + return Pair.of(1, 2); + + // Similar to the reason above, DrillOptiq.java is used for rewritting + case "LENGTH": + return Pair.of(1, 2); + + default: + return Pair.of(func.getParamCount(), func.getParamCount()); + } + } --- End diff -- Why do we have to add dummy functions? I understand in the case that we don't support variable arguments. Why is that the case here?
--- If your project is set up for it, you can reply to this email and have your reply appear on GitHub as well. If your project does not have this feature enabled and wishes so, or if the feature is enabled but not working, please contact infrastructure at infrastruct...@apache.org or file a JIRA ticket with INFRA. ---