Struct Tablesample

pub struct Tablesample<S, TSM>
where
    TSM: TablesampleMethod,
{ /* private fields */ }

Available on crate feature postgres_backend only.

Represents a query with a TABLESAMPLE clause.

Implementations

impl<S, TSM> Tablesample<S, TSM>

where TSM: TablesampleMethod,

pub fn with_seed(self, seed: f64) -> Tablesample<S, TSM>

This method allows you to specify the random number generator seed to use in the sampling method. This allows you to obtain repeatable results.

Trait Implementations

impl<S, TSM> AsQuery for Tablesample<S, TSM>

where S: Table + Clone, TSM: TablesampleMethod, <S as QuerySource>::DefaultSelection: ValidGrouping<()> + SelectableExpression<Tablesample<S, TSM>>,

type SqlType = <<Tablesample<S, TSM> as QuerySource>::DefaultSelection as Expression>::SqlType

The SQL type of Self::Query

type Query = SelectStatement<FromClause<Tablesample<S, TSM>>>

What kind of query does this type represent?

fn as_query(self) -> Self::Query

Converts a type which semantically represents a SQL query into the actual query being executed. See the trait level docs for more.

impl<S: Clone, TSM> Clone for Tablesample<S, TSM>

where TSM: TablesampleMethod + Clone,

fn clone(&self) -> Tablesample<S, TSM>

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<S: Debug, TSM> Debug for Tablesample<S, TSM>

where TSM: TablesampleMethod + Debug,

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

Formats the value using the given formatter.

impl<S, TSM> QueryFragment<Pg> for Tablesample<S, TSM>

where S: QueryFragment<Pg>, TSM: TablesampleMethod,

fn walk_ast<'b>(&'b self, out: AstPass<'_, 'b, Pg>) -> QueryResult<()>

Walk over this QueryFragment for all passes.

fn to_sql(&self, out: &mut DB::QueryBuilder, backend: &DB) -> QueryResult<()>

Available on crate feature i-implement-a-third-party-backend-and-opt-into-breaking-changes only.

Converts this QueryFragment to its SQL representation.

fn collect_binds<'b>( &'b self, out: &mut DB::BindCollector<'b>, metadata_lookup: &mut DB::MetadataLookup, backend: &'b DB, ) -> QueryResult<()>

Available on crate feature i-implement-a-third-party-backend-and-opt-into-breaking-changes only.

Serializes all bind parameters in this query.

fn is_safe_to_cache_prepared(&self, backend: &DB) -> QueryResult<bool>

Available on crate feature i-implement-a-third-party-backend-and-opt-into-breaking-changes only.

Is this query safe to store in the prepared statement cache?

fn is_noop(&self, backend: &DB) -> QueryResult<bool>

Available on crate feature i-implement-a-third-party-backend-and-opt-into-breaking-changes only.

Does walking this AST have any effect?

impl<S, TSM> QueryId for Tablesample<S, TSM>

where S: QueryId, TSM: TablesampleMethod,

const HAS_STATIC_QUERY_ID: bool = false

Can the SQL generated by Self be uniquely identified by its type?

type QueryId = ()

A type which uniquely represents Self in a SQL query.

fn query_id() -> Option<TypeId>

Returns the type id of Self::QueryId if Self::HAS_STATIC_QUERY_ID. Returns None otherwise.

impl<S, TSM> QuerySource for Tablesample<S, TSM>

where S: Table + Clone, TSM: TablesampleMethod, <S as QuerySource>::DefaultSelection: ValidGrouping<()> + SelectableExpression<Tablesample<S, TSM>>,

type FromClause = Tablesample<S, TSM>

The type returned by from_clause

type DefaultSelection = <S as QuerySource>::DefaultSelection

The type returned by default_selection

fn from_clause(&self) -> Self::FromClause

The actual FROM clause of this type. This is typically only called in QueryFragment implementations.

fn default_selection(&self) -> Self::DefaultSelection

The default select clause of this type, which should be used if no select clause was explicitly specified. This should always be a tuple of all the desired columns, not star

impl<S, TSM> Table for Tablesample<S, TSM>

where S: Table + Clone + AsQuery, TSM: TablesampleMethod, <S as Table>::PrimaryKey: SelectableExpression<Tablesample<S, TSM>>, <S as Table>::AllColumns: SelectableExpression<Tablesample<S, TSM>>, <S as QuerySource>::DefaultSelection: ValidGrouping<()> + SelectableExpression<Tablesample<S, TSM>>,

type PrimaryKey = <S as Table>::PrimaryKey

The type returned by primary_key

type AllColumns = <S as Table>::AllColumns

The type returned by all_columns

fn primary_key(&self) -> Self::PrimaryKey

Returns the primary key of this table.

fn all_columns() -> Self::AllColumns

Returns a tuple of all columns belonging to this table.

impl<S: Copy, TSM> Copy for Tablesample<S, TSM>

where TSM: TablesampleMethod + Copy,

impl<S, T, TSM> JoinTo<T> for Tablesample<S, TSM>

where S: JoinTo<T> + Table, T: Table, TSM: TablesampleMethod,