Struct Explain 

pub struct Explain<Q>(pub Q);

A wrapper around a Diesel query that transforms it into an EXPLAIN (FORMAT JSON) query.

Use this type to inspect the query execution plan without running the query.

Example:

let plan = my_query.wrap_explain().explain(&mut conn)?;
println!("{:#?}", plan);

Tuple Fields

0: Q

Implementations

impl<Q> Explain<Q>

pub fn explain<'a>(self, conn: &mut PgConnection) -> QueryResult<ExplainPlan>

where Self: LoadQuery<'a, PgConnection, String>,

Executes the wrapped query using EXPLAIN (FORMAT JSON), parses the result, and returns a structured ExplainPlan that represents the root of the query plan tree.

Errors

Returns a diesel::result::Error::DeserializationError if the JSON returned by PostgreSQL cannot be parsed into an ExplainPlan.

Trait Implementations

impl<Q: Clone> Clone for Explain<Q>

fn clone(&self) -> Explain<Q>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<Q: Query> Query for Explain<Q>

type SqlType = Text

The SQL type that this query represents.

impl<Q> QueryFragment<Pg> for Explain<Q>

where Q: QueryFragment<Pg>,

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

Walk over this QueryFragment for all passes.

impl<Q: QueryId> QueryId for Explain<Q>

const HAS_STATIC_QUERY_ID: bool

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

type QueryId = Explain<<Q as QueryId>::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<Q> RunQueryDsl<PgConnection> for Explain<Q>

fn execute(self, conn: &mut Conn) -> Result<usize, Error>

where Conn: Connection, Self: ExecuteDsl<Conn>,

Executes the given command, returning the number of rows affected.

fn load<'query, U>(self, conn: &mut Conn) -> Result<Vec<U>, Error>

where Self: LoadQuery<'query, Conn, U>,

Executes the given query, returning a Vec with the returned rows.

fn load_iter<'conn, 'query, U, B>( self, conn: &'conn mut Conn, ) -> Result<Self::RowIter<'conn>, Error>

where 'query: 'conn, U: 'conn, Self: LoadQuery<'query, Conn, U, B> + 'conn,

Executes the given query, returning an Iterator with the returned rows.

fn get_result<'query, U>(self, conn: &mut Conn) -> Result<U, Error>

where Self: LoadQuery<'query, Conn, U>,

Runs the command, and returns the affected row.

fn get_results<'query, U>(self, conn: &mut Conn) -> Result<Vec<U>, Error>

where Self: LoadQuery<'query, Conn, U>,

Runs the command, returning an Vec with the affected rows.

impl<Q: Copy> Copy for Explain<Q>