Struct mz_sql::query_model::Model

pub struct Model {
    pub(crate) top_box: BoxId,
    boxes: HashMap<BoxId, Box<RefCell<QueryBox>>>,
    box_id_gen: Gen<BoxId>,
    quantifiers: HashMap<QuantifierId, Box<RefCell<Quantifier>>>,
    quantifier_id_gen: Gen<QuantifierId>,
}

A Query Graph Model instance represents a SQL query. See the design doc for details.

In this representation, SQL queries are represented as a graph of operators, represented as boxes, that are connected via quantifiers. A top-level box represents the entry point of the query.

Each non-leaf box has a set of quantifiers, which are the inputs of the operation it represents. The quantifier adds information about how the relation represented by its input box is consumed by the parent box.

Fields

top_box: BoxId

The ID of the box representing the entry-point of the query.

boxes: HashMap<BoxId, Box<RefCell<QueryBox>>>

All boxes in the query graph model.

box_id_gen: Gen<BoxId>

Used for assigning unique IDs to query boxes.

quantifiers: HashMap<QuantifierId, Box<RefCell<Quantifier>>>

All quantifiers in the query graph model.

quantifier_id_gen: Gen<QuantifierId>

Used for assigning unique IDs to quantifiers.

Implementations

impl Model

Helper methods for the derivation of the RelationType attribute.

fn cols_type(&self, box_id: BoxId) -> Vec<ColumnType>

Infers a vector of ColumnType values for the columns of the given BoxId.

Note: this method should be used only internally in order to derive the RelationType attribute of a Model.

fn expr_type(&self, expr: &BoxScalarExpr, enclosing_box_id: BoxId) -> ColumnType

Infers a ColumnType corresponding to the given BoxScalarExpr used within the context of an enclosing BoxId.

Note: this method should be used only internally in order to derive the RelationType attribute of a Model.

fn cref_type(&self, cref: &ColumnReference, enclosing_box_id: BoxId) -> ColumnType

Looks up a ColumnType corresponding to the given ColumnReference from the RelationType attribute of the input box, assuming the ColumnReference occurs within the context of the enclosing BoxId.

Note: this method should be used only internally in order to derive the RelationType attribute of a Model.

impl Model

pub fn as_dot<'a>(
    &mut self,
    label: &str,
    expr_humanizer: &'a dyn ExprHumanizer,
    with_types: bool
) -> Result<String, Error>

impl Model

pub(crate) fn make_box(&mut self, box_type: BoxType) -> BoxId

pub(crate) fn make_select_box(&mut self) -> BoxId

pub(crate) fn boxes_iter(&self) -> impl Iterator<Item = BoundRef<'_, QueryBox>>

An iterator over immutable references to the QueryBox instances in this Model.

pub(crate) fn get_box(&self, box_id: BoxId) -> BoundRef<'_, QueryBox>

Get an immutable reference to the box identified by box_id bound to this Model.

pub(crate) fn get_mut_box(&mut self, box_id: BoxId) -> BoundRefMut<'_, QueryBox>

Get a mutable reference to the box identified by box_id bound to this Model.

pub(crate) fn make_quantifier(
    &mut self,
    quantifier_type: QuantifierType,
    input_box: BoxId,
    parent_box: BoxId
) -> QuantifierId

Create a new quantifier and adds it to the parent box

pub(crate) fn get_quantifier<'a>(
    &'a self,
    quantifier_id: QuantifierId
) -> BoundRef<'a, Quantifier>

Get an immutable reference to the box identified by box_id bound to this Model.

pub(crate) fn get_mut_quantifier<'a>(
    &'a mut self,
    quantifier_id: QuantifierId
) -> BoundRefMut<'a, Quantifier>

Get a mutable reference to the box identified by box_id bound to this Model.

pub(crate) fn try_visit_pre_post<'a, F, G, E>(
    &'a self,
    pre: &mut F,
    post: &mut G
) -> Result<(), E>where
    F: FnMut(&Model, &BoxId) -> Result<(), E>,
    G: FnMut(&Model, &BoxId) -> Result<(), E>,

Traverse the entire graph using depth-first traversal.

The function pre runs on a parent QueryBox before it runs on any of its children. The function post runs on all children QueryBoxes before it runs on a parent.

pub(crate) fn try_visit_pre_post_descendants<'a, F, G, E>(
    &'a self,
    pre: &mut F,
    post: &mut G,
    root: BoxId
) -> Result<(), E>where
    F: FnMut(&Model, &BoxId) -> Result<(), E>,
    G: FnMut(&Model, &BoxId) -> Result<(), E>,

Traverse a subgraph using depth-first traversal starting at root.

The function pre runs on a parent QueryBox before it runs on any of its children. The function post runs on all children QueryBoxes before it runs on a parent.

pub(crate) fn try_visit_mut_pre_post<'a, F, G, E>(
    &'a mut self,
    pre: &mut F,
    post: &mut G
) -> Result<(), E>where
    F: FnMut(&mut Model, &BoxId) -> Result<(), E>,
    G: FnMut(&mut Model, &BoxId) -> Result<(), E>,

Same as Model::try_visit_pre_post, but permits mutating the model.

pub(crate) fn try_visit_mut_pre_post_descendants<'a, F, G, E>(
    &'a mut self,
    pre: &mut F,
    post: &mut G,
    root: BoxId
) -> Result<(), E>where
    F: FnMut(&mut Model, &BoxId) -> Result<(), E>,
    G: FnMut(&mut Model, &BoxId) -> Result<(), E>,

Same as Model::try_visit_pre_post_descendants, but permits mutating the model.

pub(crate) fn garbage_collect(&mut self)

Removes unreferenced objects from the model.

May be invoked several times during query rewrites.

pub(crate) fn update_ids(&mut self)

Renumbers all the boxes and quantifiers in the model starting from 0.

Intended to be called after Model::garbage_collect.

Renumbering the model does not save memory or improve the performance of traversing the model, but it does make the Dot graph easier to parse.

impl Model

pub fn optimize(&mut self)

impl Model

pub fn validate(&self) -> ValidationResult

Validate a model with a default validator chain.

Trait Implementations

impl Debug for Model

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

Formats the value using the given formatter.

impl Default for Model

fn default() -> Model

Returns the “default value” for a type.

impl TryFrom<HirRelationExpr> for Model

type Error = QGMError

The type returned in the event of a conversion error.

fn try_from(expr: HirRelationExpr) -> Result<Self, Self::Error>

Performs the conversion.

impl TryFrom<Model> for HirRelationExpr

type Error = QGMError

The type returned in the event of a conversion error.

fn try_from(model: Model) -> Result<Self, Self::Error>

Performs the conversion.

impl TryFrom<Model> for MirRelationExpr

type Error = QGMError

The type returned in the event of a conversion error.

fn try_from(model: Model) -> Result<Self, Self::Error>

Performs the conversion.