Aggregation.cpp File Reference

Aggregation operator and accumulator implementations. More...

#include "Aggregation.h"
#include <string>
#include <stdexcept>
#include "utils/lsyscache.h"
#include "utils/elog.h"
#include "provsql_error.h"

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Classes
struct	False<... >
struct	StandardAgg< T >
	Base aggregator template for scalar types (int, float, bool, string). More...
struct	SumAgg< T >
	Aggregator implementing SUM for integer or float types. More...
struct	MinAgg< T >
	Aggregator implementing MIN for integer or float types. More...
struct	MaxAgg< T >
	Aggregator implementing MAX for integer or float types. More...
struct	ChooseAgg< T >
	Aggregator implementing CHOOSE (returns the first non-NULL input). More...
struct	AvgAgg< T >
	Aggregator implementing AVG; always returns a float result. More...

Functions
AggregationOperator	getAggregationOperator (Oid oid)
	Map a PostgreSQL aggregate function OID to an AggregationOperator.
ComparisonOperator	cmpOpFromOid (Oid op_oid, bool &ok)
	Map a PostgreSQL comparison-operator OID to a ComparisonOperator.
std::unique_ptr< Aggregator >	makeAggregator (AggregationOperator op, ValueType t)
	Create a concrete Aggregator for the given operator and value type.

Detailed Description

Aggregation operator and accumulator implementations.

Implements the two factory functions declared in Aggregation.h:

• getAggregationOperator(): maps a PostgreSQL aggregate function OID (looked up by name via get_func_name()) to an AggregationOperator enum value.
• makeAggregator(): constructs a concrete Aggregator subclass for the given operator/type combination.

Each built aggregation function × value-type combination has its own Aggregator subclass defined locally in this file (e.g. SumAgg<long>, MinAgg<double>, ChooseAgg<long>). Only the aggregates the Monte-Carlo sampler and the subset enumerator evaluate directly are built: the numeric ones (SUM / COUNT / MIN / MAX / AVG) and CHOOSE (the categorical analog, decided by the exhaustive subset enumerator). The boolean (bool_or / bool_and) and array_agg aggregates are resolved to a Boolean subcircuit by the m-semiring HAVING rewrite (having_semantics) and so never reach makeAggregator.

Definition in file Aggregation.cpp.

Function Documentation

cmpOpFromOid()

ComparisonOperator cmpOpFromOid	(	Oid	op_oid,
		bool &	ok )

Map a PostgreSQL comparison-operator OID to a ComparisonOperator.

The OID is the one stored in gate_cmp's info1 field (the OID of one of the six standard comparators =, <>, <, <=, >, >=). The translation goes via get_opname() so it is operand-type agnostic.

Parameters

[in]	op_oid	Comparison-operator OID.
[out]	ok	Set to true on a recognised comparator, false when op_oid does not resolve in pg_operator or its name is not one of the six standard ones.

Returns

The matching ComparisonOperator on success; an unspecified value (currently EQ) when ok is false.

Definition at line 71 of file Aggregation.cpp.

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getAggregationOperator()

AggregationOperator getAggregationOperator

(

Oid

oid

)

Map a PostgreSQL aggregate function OID to an AggregationOperator.

Parameters

oid	OID of the aggregate function (e.g. F_COUNT_ANY, F_SUM_INT4).

Returns

The corresponding AggregationOperator.

Definition at line 34 of file Aggregation.cpp.

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makeAggregator()

std::unique_ptr< Aggregator > makeAggregator	(	AggregationOperator	op,
		ValueType	t )

Create a concrete Aggregator for the given operator and value type.

Parameters

op	The aggregation function to implement.
t	The type of input values that will be accumulated.

Returns

A heap-allocated Aggregator, or nullptr if the combination is not supported.

Definition at line 230 of file Aggregation.cpp.

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