Struct mz_coord::session::Session

pub struct Session<T = Timestamp> {
    conn_id: u32,
    prepared_statements: HashMap<String, PreparedStatement>,
    portals: HashMap<String, Portal>,
    transaction: TransactionStatus<T>,
    pcx: Option<PlanContext>,
    user: String,
    vars: Vars,
    drop_sinks: Vec<(ComputeInstanceId, GlobalId)>,
}

A session holds per-connection state.

Fields

conn_id: u32

prepared_statements: HashMap<String, PreparedStatement>

portals: HashMap<String, Portal>

transaction: TransactionStatus<T>

pcx: Option<PlanContext>

user: String

vars: Vars

drop_sinks: Vec<(ComputeInstanceId, GlobalId)>

Implementations

impl<T: CoordTimestamp> Session<T>

pub fn new(conn_id: u32, user: String) -> Session<T>

Creates a new session for the specified connection ID.

pub fn dummy() -> Session<T>

Creates a new dummy session.

Dummy sessions are intended for use when executing queries on behalf of the system itself, rather than on behalf of a user.

fn new_internal(conn_id: u32, user: String) -> Session<T>

pub fn conn_id(&self) -> u32

Returns the connection ID associated with the session.

pub fn pcx(&self) -> &PlanContext

Returns the current transaction’s PlanContext. Panics if there is not a current transaction.

pub fn start_transaction(
    self,
    wall_time: DateTime<Utc>,
    access: Option<TransactionAccessMode>
) -> Self

Starts an explicit transaction, or changes an implicit to an explicit transaction.

pub fn start_transaction_implicit(
    self,
    wall_time: DateTime<Utc>,
    stmts: usize
) -> Self

Starts either a single statement or implicit transaction based on the number of statements, but only if no transaction has been started already.

pub fn clear_transaction(
    &mut self
) -> (Vec<(ComputeInstanceId, GlobalId)>, TransactionStatus<T>)

Clears a transaction, setting its state to Default and destroying all portals. Returned are:

• sinks that were started in this transaction and need to be dropped
• the cleared transaction so its operations can be handled

The Postgres protocol docs specify:

a named portal object lasts till the end of the current transaction and An unnamed portal is destroyed at the end of the transaction

pub fn fail_transaction(self) -> Self

Marks the current transaction as failed.

pub fn transaction(&self) -> &TransactionStatus<T>

Returns the current transaction status.

pub fn add_transaction_ops(
    &mut self,
    add_ops: TransactionOps<T>
) -> Result<(), CoordError>

Adds operations to the current transaction. An error is produced if they cannot be merged (i.e., a read cannot be merged to an insert).

pub fn add_drop_sink(
    &mut self,
    compute_instance: ComputeInstanceId,
    name: GlobalId
)

Adds a sink that will need to be dropped when the current transaction is cleared.

pub fn clear_transaction_ops(&mut self)

Sets the transaction ops to TransactionOps::None. Must only be used after verifying that no transaction anomalies will occur if cleared.

pub fn get_transaction_timestamp(&self) -> Option<T>

Returns the transaction’s read timestamp, if set.

Returns None if there is no active transaction, or if the active transaction is not a read transaction.

pub fn set_prepared_statement(
    &mut self,
    name: String,
    statement: PreparedStatement
)

Registers the prepared statement under name.

pub fn remove_prepared_statement(&mut self, name: &str) -> bool

Removes the prepared statement associated with name.

Returns whether a statement previously existed.

pub fn remove_all_prepared_statements(&mut self)

Removes all prepared statements.

pub fn get_prepared_statement_unverified(
    &self,
    name: &str
) -> Option<&PreparedStatement>

Retrieves the prepared statement associated with name.

This is unverified and could be incorrect if the underlying catalog has changed.

pub fn get_prepared_statement_mut_unverified(
    &mut self,
    name: &str
) -> Option<&mut PreparedStatement>

Retrieves the prepared statement associated with name.

This is unverified and could be incorrect if the underlying catalog has changed.

pub fn prepared_statements(&self) -> &HashMap<String, PreparedStatement>

Returns the prepared statements for the session.

pub fn set_portal(
    &mut self,
    portal_name: String,
    desc: StatementDesc,
    stmt: Option<Statement<Raw>>,
    params: Vec<(Datum<'_>, ScalarType)>,
    result_formats: Vec<Format>,
    catalog_revision: u64
) -> Result<(), CoordError>

Binds the specified portal to the specified prepared statement.

If the prepared statement contains parameters, the values and types of those parameters must be provided in params. It is the caller’s responsibility to ensure that the correct number of parameters is provided.

and is stored on the portal.

pub fn remove_portal(&mut self, portal_name: &str) -> bool

Removes the specified portal.

If there is no such portal, this method does nothing. Returns whether that portal existed.

pub fn get_portal_unverified(&self, portal_name: &str) -> Option<&Portal>

Retrieves a reference to the specified portal.

If there is no such portal, returns None.

pub fn get_portal_unverified_mut(
    &mut self,
    portal_name: &str
) -> Option<&mut Portal>

Retrieves a mutable reference to the specified portal.

If there is no such portal, returns None.

pub fn create_new_portal(
    &mut self,
    stmt: Option<Statement<Raw>>,
    desc: StatementDesc,
    parameters: Params,
    result_formats: Vec<Format>,
    catalog_revision: u64
) -> Result<String, CoordError>

Creates and installs a new portal.

pub fn reset(&mut self) -> Vec<(ComputeInstanceId, GlobalId)>

Resets the session to its initial state. Returns sinks that need to be dropped.

pub fn user(&self) -> &str

Returns the name of the user who owns this session.

pub fn vars(&self) -> &Vars

Returns a reference to the variables in this session.

pub fn vars_mut(&mut self) -> &mut Vars

Returns a mutable reference to the variables in this session.

pub fn grant_write_lock(&mut self, guard: OwnedMutexGuard<()>)

Grants the coordinator’s write lock guard to this session’s inner transaction.

Panics

If the inner transaction is idle. See TransactionStatus::grant_write_lock.

pub fn has_write_lock(&self) -> bool

Returns whether or not this session currently holds the write lock.

Trait Implementations

impl<T: Debug> Debug for Session<T>

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

Formats the value using the given formatter.