| // Licensed to the Apache Software Foundation (ASF) under one |
| // or more contributor license agreements. See the NOTICE file |
| // distributed with this work for additional information |
| // regarding copyright ownership. The ASF licenses this file |
| // to you under the Apache License, Version 2.0 (the |
| // "License"); you may not use this file except in compliance |
| // with the License. You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, |
| // software distributed under the License is distributed on an |
| // "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| // KIND, either express or implied. See the License for the |
| // specific language governing permissions and limitations |
| // under the License. |
| |
| |
| #ifndef IMPALA_UDF_SAMPLE_UDA_H |
| #define IMPALA_UDF_SAMPLE_UDA_H |
| |
| #include <udf/udf.h> |
| |
| using namespace impala_udf; |
| |
| /// This is an example of the COUNT aggregate function. |
| void CountInit(FunctionContext* context, BigIntVal* val); |
| void CountUpdate(FunctionContext* context, const IntVal& input, BigIntVal* val); |
| void CountMerge(FunctionContext* context, const BigIntVal& src, BigIntVal* dst); |
| BigIntVal CountFinalize(FunctionContext* context, const BigIntVal& val); |
| |
| /// This is an example of the AVG(double) aggregate function. This function needs to |
| /// maintain two pieces of state, the current sum and the count. We do this using |
| /// the BufferVal intermediate type. When this UDA is registered, it would specify |
| /// 16 bytes (8 byte sum + 8 byte count) as the size for this buffer. |
| void AvgInit(FunctionContext* context, BufferVal* val); |
| void AvgUpdate(FunctionContext* context, const DoubleVal& input, BufferVal* val); |
| void AvgMerge(FunctionContext* context, const BufferVal& src, BufferVal* dst); |
| DoubleVal AvgFinalize(FunctionContext* context, const BufferVal& val); |
| |
| /// This is a sample of implementing the STRING_CONCAT aggregate function. |
| /// Example: select string_concat(string_col, ",") from table |
| void StringConcatInit(FunctionContext* context, StringVal* val); |
| void StringConcatUpdate(FunctionContext* context, const StringVal& arg1, |
| const StringVal& arg2, StringVal* val); |
| void StringConcatMerge(FunctionContext* context, const StringVal& src, StringVal* dst); |
| StringVal StringConcatFinalize(FunctionContext* context, const StringVal& val); |
| |
| #endif |