Vertica::ScalarFunction Class Reference

Interface for User-Defined Scalar Function (UDSF). A UDSF produces a single value from a row of data.

Inheritance diagram for Vertica::ScalarFunction:

Collaboration diagram for Vertica::ScalarFunction:

Public Member Functions
void cancelUDX (ServerInterface &srvInterface)
virtual void destroy (ServerInterface &srvInterface, const SizedColumnTypes &argTypes)
virtual void destroy (ServerInterface &srvInterface, const SizedColumnTypes &argTypes, SessionParamWriterMap &udSessionParams)
virtual void getOutputRange (ServerInterface &srvInterface, ValueRangeReader &inRange, ValueRangeWriter &outRange)
bool isCanceled () const
virtual void processBlock (ServerInterface &srvInterface, BlockReader &arg_reader, BlockWriter &res_writer)=0
virtual void setup (ServerInterface &srvInterface, const SizedColumnTypes &argTypes)
Protected Member Functions
virtual void cancel (ServerInterface &srvInterface)
Friends
struct ::CPPExecContext
class ::EE::VEval
class ::UdfSupport

Detailed Description

Interface for User-Defined Scalar Function (UDSF). A UDSF produces a single value from a row of data.

A UDSF can be used anywhere a native function can be used, except CREATE TABLE BY PARTITION and SEGMENTED BY expressions.

A ScalarFunction must have an associated ScalarFunctionFactory.

Member Function Documentation

◆cancel()

virtual void Vertica::UDXObject::cancel(ServerInterface & srvInterface)

inlineprotectedvirtualinherited

Cancel callback to be overridden by the UDX. Called when the query running the UDX has been canceled.

Note

  • This method will be invoked at most once per UDX object. Once a UDX object has been canceled, it will never be un-canceled.

  • This method may be called from a separate thread, concurrently with other methods of this UDX object (but never the constructor or destructor). Implementations must be thread-safe with all methods of this UDX.

  • This method will be invoked for either an explicit user cancel, or in the event of an error during query execution.

Referenced by Vertica::UDXObject::cancelUDX().

◆cancelUDX()

void Vertica::UDXObject::cancelUDX(ServerInterface & srvInterface)

inline inherited Cancel callback invoked when the query running the UDX has been canceled. See cancel().

◆destroy() [1/2]

virtual void Vertica::UDXFunction::destroy(ServerInterface & srvInterface, const SizedColumnTypes & argTypes)

inlinevirtualinherited

Perform per instance destruction. This function may throw errors

Referenced by Vertica::UDXFunction::destroy().

◆destroy() [2/2]

virtual void Vertica::UDXFunction::destroy(ServerInterface & srvInterface, const SizedColumnTypes & argTypes, SessionParamWriterMap & udSessionParams)

inlinevirtualinherited

Perform per instance destruction and write session parameters to be used by UDxs that are invoked after this one returns. This function may throw errors

◆getOutputRange()

virtual void Vertica::ScalarFunction::getOutputRange(ServerInterface & srvInterface, ValueRangeReader & inRange, ValueRangeWriter & outRange)

inlinevirtual

Invoke a user defined function to determine the output value range of this function. Ranges are represented by a minimum/maximum pair of values (inclusive). The developer is responsible to provide an output value range on the basis of the input argument ranges. Minimum/maximum values of ranges are of the same type as defined in the metadata class getPrototype() function.

Parameters

  • srvInterface: a ServerInterface object used to communicate with Vertica
  • inRange: input value range
  • outRange: output value range

Remarks

By default, the ValueRangeWriter object can have NULL values, values in the range are unsorted, and it is unbounded, i.e., the following functions return as follows:

  • outRange.canHaveNulls() == true

  • outRange.getSortedness() == EE::SORT_UNORDERED

  • outRange.isBounded() == false

Note

  • This methods may be invoked by different threads at different times, and by a different thread than the constructor.

  • C++ exceptions may NOT be thrown out of this method. Use the vertica specific vt_throw_exception() function or vt_report_error() macro instead

  • Invoking vt_throw_exception() or vt_report_error() from this method will not stop the function execution, which may still complete successfully. Instead, the output range will be discarded, and a WARNING message will be written to the Vertica log

◆isCanceled()

bool Vertica::UDXObject::isCanceled() const

inline inherited Returns true iff this UDX has been canceled

◆processBlock()

virtual void Vertica::ScalarFunction::processBlock(ServerInterface & srvInterface, BlockReader & arg_reader, BlockWriter & res_writer)

pure virtual Invoke a user defined function on a set of rows. As the name suggests, a batch of rows are passed in for every invocation to amortize performance.

Parameters

  • srvInterface: a ServerInterface object used to communicate with Vertica
  • arg_reader: input rows
  • res_writer: output location

Note

  • This methods may be invoked by different threads at different times, and by a different thread than the constructor.

  • The order in which the function sees rows is not guaranteed.

  • C++ exceptions may NOT be thrown out of this method. Use the vertica specific vt_throw_exception() function or vt_report_error() macro instead

◆setup()

virtual void Vertica::UDXFunction::setup(ServerInterface & srvInterface, const SizedColumnTypes & argTypes)

inlinevirtualinherited

Perform per instance initialization. This function may throw errors.