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			307 lines
		
	
	
		
			11 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
/* Copyright (C) 2014 InfiniDB, Inc.
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   Copyright (c) 2019 MariaDB Corporation
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   This program is free software; you can redistribute it and/or
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   modify it under the terms of the GNU General Public License
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   as published by the Free Software Foundation; version 2 of
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   the License.
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   This program is distributed in the hope that it will be useful,
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   but WITHOUT ANY WARRANTY; without even the implied warranty of
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   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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   GNU General Public License for more details.
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   You should have received a copy of the GNU General Public License
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   along with this program; if not, write to the Free Software
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   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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   MA 02110-1301, USA. */
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/***********************************************************************
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 *   $Id$
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 *
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 *
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 ***********************************************************************/
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/**
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 * MariaDB ColumnStore interface for writing a user defined function (UDF).
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 *
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 * The basic steps are:
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 *
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 * 1. add the UDF function interface in udfsdk.h
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 * 2. add the UDF function implementation in udfsdk.cpp
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 * 3. add the connector stub for this UDF function in udfsdk.cpp
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 * 4. build the dynamic library libudfsdk
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 * 5. put the library in /usr/local/mariadb/columnstore/lib of all modules
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 * 6. restart MariaDB ColumnStore
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 * 7. Register the new functions with the commands like:
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 *
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 *    CREATE FUNCTION mcs_add returns REAL soname 'libudfsdk.so';
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 *    CREATE FUNCTION mcs_isnull returns BOOL soname 'libudfsdk.so';
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 *
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 * The UDF functions run distributedly in the ColumnStore engine. The evaluation
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 * is row by row. Aggregate UDF is currently not supported. Two examples are
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 * given in this file to demonstrate the steps that it takes to create a UDF
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 * function. More examples can be found in utils/funcexp/func_*.cpp.
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 */
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#include "funcexp.h"
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#include "functor.h"
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#define EXPORT
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namespace udfsdk
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{
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/**
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 * UDFSDK interface. Do not make modification here.
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 */
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class UDFSDK
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{
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 public:
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  EXPORT UDFSDK();
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  EXPORT ~UDFSDK();
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  EXPORT funcexp::FuncMap UDFMap() const;
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 protected:
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 private:
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  // defaults okay
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  // UDFSDK(const UDFSDK& rhs);
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  // UDFSDK& operator=(const UDFSDK& rhs);
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};
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/**
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 * Example: MCS_add (args1, args2)
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 *
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 * MCS_add takes two arguments of any data type. It returns a double result.
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 *
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 * The function interface is defined here. All UDF functions are derived from
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 * class funcexp::Func. A set of getXXXval interface APIs are declared in the
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 * parent class Func, which will be called by IDB function and expression (F&E)
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 * framwork when evaluating the function. Which API to be called depends on
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 * the context of the function in the SQL query, i.e., the result type that
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 * the function is expected to return.
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 *
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 * For example, given the following two queries, different APIs will be called
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 * to evaluate the function MCS_add.
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 *
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 * select MCS_add(int1, int2) from t1;
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 * getDoubleVal() is called, because the result type of MCS_add is DOUBLE(real).
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 *
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 * select substr(string1, int1, MCS_add(int1+int2));
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 * getIntVal() will be called, because MCS_add() is passed as the third argument
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 * to substr function, and an integer result is expected.
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 *
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 * If one API is not implemented but called for a function, MCS-5001 error will
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 * be returned.
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 */
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class MCS_add : public funcexp::Func
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{
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 public:
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  /*
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   * Constructor. Pass the function name to the base constructor.
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   */
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  MCS_add() : Func("mcs_add")
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  {
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  }
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  /*
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   * Destructor. MCS_add does not need to do anything here to clean up.
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   */
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  ~MCS_add() override = default;
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  /**
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   * Decide on the function's operation type
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   *
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   * Operation type decides which API needs to be called for each function
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   * parameter. Sometimes it is obvious. e.g. for function substr (c1, c2, c3),
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   * one knows that getStrVal(), getIntVal() and getIntVal() should be called for
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   * the three parameters in sequence. In that case, a dummy type can be returned
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   * because it won't be used in the function implementation. Sometimes the
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   * operation type is decided by the data type of the function parameters.
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   * e.g., isnull(c1) function, one should call the corresponding getXXXval()
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   * function that in compatible with the result type of c1.
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   *
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   * @parm fp vector of function parameters
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   *       Each element is a boost::shared_ptr of execplan::ParseTree. class
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   *       ParseTree is defined in ~/dbcon/execplan/parsetree.h
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   * @parm resultType result type of this function
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   *       Sometimes it may affect the operation type, but most of the time it
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   *       can be ignored. Struct ColType is defined in ~/dbcon/execplan/calpontsystemcatalog.h
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   * @return operation type for this function
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   *
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   * This function is called only one from the connector. Once it's determined, it
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   * will be passed to the getXXXval() APIs during function evaluation.
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   */
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  execplan::CalpontSystemCatalog::ColType operationType(
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      funcexp::FunctionParm& fp, execplan::CalpontSystemCatalog::ColType& resultType) override;
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  /**
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   * Returns an integer result of this function.
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   * All the getXXXvalue APIs take the same arguments. They will be called
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   * for every row in the result set when the function is being evaluated.
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   * So these functions needs to be efficient.
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   *
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   * @parm row reference of the current row
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   * @parm fp function parameters
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   * @parm isNull NULL indicator throughout this function evaluation.
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   *       the same reference is passed to all the function argument
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   *       evaluations. One always need to know if any argument is NULL
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   *       to decide the result of the function. It's explained in detail
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   *       in MCS_isnull() function example.
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   * @parm op_ct the operation type that is determined in operationType().
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   *
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   */
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  int64_t getIntVal(rowgroup::Row& row, funcexp::FunctionParm& fp, bool& isNull,
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                    execplan::CalpontSystemCatalog::ColType& op_ct) override;
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  /**
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   * Returns a double result of this function.
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   */
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  double getDoubleVal(rowgroup::Row& row, funcexp::FunctionParm& fp, bool& isNull,
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                      execplan::CalpontSystemCatalog::ColType& op_ct) override;
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  /**
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   * Returns a long double result of this function.
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   */
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  long double getLongDoubleVal(rowgroup::Row& row, funcexp::FunctionParm& fp, bool& isNull,
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                               execplan::CalpontSystemCatalog::ColType& op_ct) override;
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  /**
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   * Returns a float result of this function.
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   */
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  float getFloatVal(rowgroup::Row& row, funcexp::FunctionParm& fp, bool& isNull,
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                    execplan::CalpontSystemCatalog::ColType& op_ct) override;
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  /**
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   * Returns a string result of this function.
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   */
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  std::string getStrVal(rowgroup::Row& row, funcexp::FunctionParm& fp, bool& isNull,
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                        execplan::CalpontSystemCatalog::ColType& op_ct) override;
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  /**
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   * Returns a bool result of this function.
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   */
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  bool getBoolVal(rowgroup::Row& row, funcexp::FunctionParm& fp, bool& isNull,
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                  execplan::CalpontSystemCatalog::ColType& op_ct) override;
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  /**
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   * Returns a decimal result of this function.
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   *
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   * IDB_Decimal is defined in ~/execplan/treenode.h
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   */
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  execplan::IDB_Decimal getDecimalVal(rowgroup::Row& row, funcexp::FunctionParm& fp, bool& isNull,
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                                      execplan::CalpontSystemCatalog::ColType& op_ct) override;
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  /**
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   * Returns an integer representation of a date result of the function.
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   *
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   * Check the date/time functions in ~/utils/funcexp for implementation
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   * example of this API.
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   */
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  int32_t getDateIntVal(rowgroup::Row& row, funcexp::FunctionParm& fp, bool& isNull,
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                        execplan::CalpontSystemCatalog::ColType& op_ct) override;
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  /**
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   * Returns an integer representation of a datetime result of the function.
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   *
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   * Check the date/time functions in ~/utils/funcexp for implementation
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   * example of this API.
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   */
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  int64_t getDatetimeIntVal(rowgroup::Row& row, funcexp::FunctionParm& fp, bool& isNull,
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                            execplan::CalpontSystemCatalog::ColType& op_ct) override;
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};
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/**
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 * Example: MCS_isnull(arg1)
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 *
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 * The purpose of this example is to demostrate the NULL handling in the UDF interface
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 */
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class MCS_isnull : public funcexp::Func
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{
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 public:
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  /*
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   * Constructor. Pass the function name to the base constructor.
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   */
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  MCS_isnull() : Func("mcs_isnull")
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  {
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  }
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  /*
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   * Destructor. MCS_add does not need to do anything here to clean up.
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   */
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  ~MCS_isnull() override = default;
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  /**
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   * Decide on the function's operation type
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   */
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  execplan::CalpontSystemCatalog::ColType operationType(
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      funcexp::FunctionParm& fp, execplan::CalpontSystemCatalog::ColType& resultType) override;
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  /**
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   * Returns an integer result of this function.
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   */
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  int64_t getIntVal(rowgroup::Row& row, funcexp::FunctionParm& fp, bool& isNull,
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                    execplan::CalpontSystemCatalog::ColType& op_ct) override;
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  /**
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   * Returns a double result of this function.
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   */
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  double getDoubleVal(rowgroup::Row& row, funcexp::FunctionParm& fp, bool& isNull,
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                      execplan::CalpontSystemCatalog::ColType& op_ct) override;
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  /**
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   * Returns a double result of this function.
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   */
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  long double getLongDoubleVal(rowgroup::Row& row, funcexp::FunctionParm& fp, bool& isNull,
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                               execplan::CalpontSystemCatalog::ColType& op_ct) override;
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  /**
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   * Returns a float result of this function.
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   */
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  float getFloatVal(rowgroup::Row& row, funcexp::FunctionParm& fp, bool& isNull,
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                    execplan::CalpontSystemCatalog::ColType& op_ct) override;
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  /**
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   * Returns a string result of this function.
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   */
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  std::string getStrVal(rowgroup::Row& row, funcexp::FunctionParm& fp, bool& isNull,
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                        execplan::CalpontSystemCatalog::ColType& op_ct) override;
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  /**
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   * Returns a bool result of this function.
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   */
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  bool getBoolVal(rowgroup::Row& row, funcexp::FunctionParm& fp, bool& isNull,
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                  execplan::CalpontSystemCatalog::ColType& op_ct) override;
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  /**
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   * Returns a decimal result of this function.
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   *
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   * IDB_Decimal is defined in ~/execplan/treenode.h
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   */
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  execplan::IDB_Decimal getDecimalVal(rowgroup::Row& row, funcexp::FunctionParm& fp, bool& isNull,
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                                      execplan::CalpontSystemCatalog::ColType& op_ct) override;
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  /**
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   * Returns an integer representation of a date result of the function.
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   *
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   * Check the date/time functions in ~/utils/funcexp for implementation
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   * example of this API.
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   */
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  int32_t getDateIntVal(rowgroup::Row& row, funcexp::FunctionParm& fp, bool& isNull,
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                        execplan::CalpontSystemCatalog::ColType& op_ct) override;
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  /**
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   * Returns an integer representation of a datetime result of the function.
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   *
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   * Check the date/time functions in ~/utils/funcexp for implementation
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   * example of this API.
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   */
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  int64_t getDatetimeIntVal(rowgroup::Row& row, funcexp::FunctionParm& fp, bool& isNull,
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                            execplan::CalpontSystemCatalog::ColType& op_ct) override;
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};
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}  // namespace udfsdk
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#undef EXPORT |