Struct mz_adapter::coord::statement_logging::StatementLogging

pub(crate) struct StatementLogging {
    executions_begun: BTreeMap<Uuid, StatementBeganExecutionRecord>,
    unlogged_sessions: BTreeMap<Uuid, SessionHistoryEvent>,
    reproducible_rng: ChaCha8Rng,
    pending_statement_execution_events: Vec<(Row, Diff)>,
    pending_prepared_statement_events: Vec<PreparedStatementEvent>,
    pending_session_events: Vec<Row>,
    pending_statement_lifecycle_events: Vec<Row>,
    now: NowFn,
    tokens: u64,
    last_logged_ts_seconds: u64,
    throttled_count: usize,
}

Fields

executions_begun: BTreeMap<Uuid, StatementBeganExecutionRecord>

Information about statement executions that have been logged but not finished.

This map needs to have enough state left over to later retract the system table entries (so that we can update them when the execution finished.)

unlogged_sessions: BTreeMap<Uuid, SessionHistoryEvent>

Information about sessions that have been started, but which have not yet been logged in mz_session_history. They may be logged as part of a statement being executed (and chosen for logging).

reproducible_rng: ChaCha8Rng

A reproducible RNG for deciding whether to sample statement executions. Only used by tests; otherwise, rand::thread_rng() is used. Controlled by the system var statement_logging_use_reproducible_rng.

pending_statement_execution_events: Vec<(Row, Diff)>

pending_prepared_statement_events: Vec<PreparedStatementEvent>

pending_session_events: Vec<Row>

pending_statement_lifecycle_events: Vec<Row>

now: NowFn

tokens: u64

The number of bytes that we are allowed to emit for statement logging without being throttled. Increases at a rate of mz_sql::session::vars::STATEMENT_LOGGING_TARGET_DATA_RATE per second, up to a max value of mz_sql::session::vars::STATEMENT_LOGGING_MAX_DATA_CREDIT.

last_logged_ts_seconds: u64

The last time at which a statement was logged.

throttled_count: usize

The number of statements that have been throttled since the last successfully logged statement.

Implementations

impl StatementLogging

pub(crate) fn new(now: NowFn) -> Self

fn throttling_check( &mut self, cost: u64, target_data_rate: u64, max_data_credit: Option<u64> ) -> Option<usize>

Check if we need to drop a statement due to throttling, and update internal data structures appropriately.

Returns None if we must throttle this statement, and Some(n) otherwise, where n is the number of statements that were dropped due to throttling before this one.

Trait Implementations

impl Debug for StatementLogging

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

Formats the value using the given formatter.