Enum postgres_parser::sys::SubLinkType

#[repr(u32)]pub enum SubLinkType {
    EXISTS_SUBLINK,
    ALL_SUBLINK,
    ANY_SUBLINK,
    ROWCOMPARE_SUBLINK,
    EXPR_SUBLINK,
    MULTIEXPR_SUBLINK,
    ARRAY_SUBLINK,
    CTE_SUBLINK,
}

SubLink

A SubLink represents a subselect appearing in an expression, and in some cases also the combining operator(s) just above it. The subLinkType indicates the form of the expression represented: EXISTS_SUBLINK EXISTS(SELECT ...) ALL_SUBLINK (lefthand) op ALL (SELECT ...) ANY_SUBLINK (lefthand) op ANY (SELECT ...) ROWCOMPARE_SUBLINK (lefthand) op (SELECT ...) EXPR_SUBLINK (SELECT with single targetlist item ...) MULTIEXPR_SUBLINK (SELECT with multiple targetlist items ...) ARRAY_SUBLINK ARRAY(SELECT with single targetlist item ...) CTE_SUBLINK WITH query (never actually part of an expression) For ALL, ANY, and ROWCOMPARE, the lefthand is a list of expressions of the same length as the subselect's targetlist. ROWCOMPARE will always have a list with more than one entry; if the subselect has just one target then the parser will create an EXPR_SUBLINK instead (and any operator above the subselect will be represented separately). ROWCOMPARE, EXPR, and MULTIEXPR require the subselect to deliver at most one row (if it returns no rows, the result is NULL). ALL, ANY, and ROWCOMPARE require the combining operators to deliver boolean results. ALL and ANY combine the perrow results using AND and OR semantics respectively. ARRAY requires just one target column, and creates an array of the target column's type using any number of rows resulting from the subselect.

SubLink is classed as an Expr node, but it is not actually executable; it must be replaced in the expression tree by a SubPlan node during planning.

NOTE: in the raw output of gram.y, testexpr contains just the raw form of the lefthand expression (if any), and operName is the String name of the combining operator. Also, subselect is a raw parsetree. During parse analysis, the parser transforms testexpr into a complete boolean expression that compares the lefthand value(s) to PARAM_SUBLINK nodes representing the output columns of the subselect. And subselect is transformed to a Query. This is the representation seen in saved rules and in the rewriter.

In EXISTS, EXPR, MULTIEXPR, and ARRAY SubLinks, testexpr and operName are unused and are always null.

subLinkId is currently used only for MULTIEXPR SubLinks, and is zero in other SubLinks. This number identifies different multipleassignment subqueries within an UPDATE statement's SET list. It is unique only within a particular targetlist. The output column(s) of the MULTIEXPR are referenced by PARAM_MULTIEXPR Params appearing elsewhere in the tlist.

The CTE_SUBLINK case never occurs in actual SubLink nodes, but it is used in SubPlans generated for WITH subqueries.

Variants

EXISTS_SUBLINK

ALL_SUBLINK

ANY_SUBLINK

ROWCOMPARE_SUBLINK

EXPR_SUBLINK

MULTIEXPR_SUBLINK

ARRAY_SUBLINK

CTE_SUBLINK

Trait Implementations

impl Clone for SubLinkType

fn clone(&self) -> SubLinkType

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for SubLinkType

impl Debug for SubLinkType

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for SubLinkType

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error> where
    __D: Deserializer<'de>, 

Deserialize this value from the given Serde deserializer.

impl Eq for SubLinkType

impl Hash for SubLinkType

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<SubLinkType> for SubLinkType

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

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

#[must_use]fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl Serialize for SubLinkType

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error> where
    __S: Serializer, 

Serialize this value into the given Serde serializer.

impl StructuralEq for SubLinkType

impl StructuralPartialEq for SubLinkType