Struct postgres_parser::sys::GroupingFunc

#[repr(C)]pub struct GroupingFunc {
    pub xpr: Expr,
    pub args: *mut List,
    pub refs: *mut List,
    pub cols: *mut List,
    pub agglevelsup: Index,
    pub location: c_int,
}

GroupingFunc

A GroupingFunc is a GROUPING(...) expression, which behaves in many ways like an aggregate function (e.g. it "belongs" to a specific query level, which might not be the one immediately containing it), but also differs in an important respect: it never evaluates its arguments, they merely designate expressions from the GROUP BY clause of the query level to which it belongs.

The spec defines the evaluation of GROUPING() purely by syntactic replacement, but we make it a real expression for optimization purposes so that one Agg node can handle multiple grouping sets at once. Evaluating the result only needs the column positions to check against the grouping set being projected. However, for EXPLAIN to produce meaningful output, we have to keep the original expressions around, since expression deparse does not give us any feasible way to get at the GROUP BY clause.

Also, we treat two GroupingFunc nodes as equal if they have equal arguments lists and agglevelsup, without comparing the refs and cols annotations.

In raw parse output we have only the args list; parse analysis fills in the refs list, and the planner fills in the cols list.

Fields

xpr: Expr

args: *mut List

refs: *mut List

arguments, not evaluated but kept for benefit of EXPLAIN etc.

cols: *mut List

ressortgrouprefs of arguments

agglevelsup: Index

actual column positions set by planner

location: c_int

same as Aggref.agglevelsup

Trait Implementations

impl Debug for GroupingFunc

fn fmt(&self, f: &mut Formatter) -> Result

Formats the value using the given formatter.

impl Default for GroupingFunc

fn default() -> Self

Returns the "default value" for a type.

impl Eq for GroupingFunc

impl Hash for GroupingFunc

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given [Hasher].

fn hash_slice<H>(data: &[Self], state: &mut H) where
    H: Hasher, 

Feeds a slice of this type into the given [Hasher].

impl PartialEq<GroupingFunc> for GroupingFunc

fn eq(&self, other: &GroupingFunc) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &GroupingFunc) -> bool

This method tests for !=.

impl StructuralEq for GroupingFunc

impl StructuralPartialEq for GroupingFunc