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rivet::source

Trait Source 

Source 
pub trait Source: Send {
    // Required methods
    fn export(
        &mut self,
        request: &ExportRequest<'_>,
        sink: &mut dyn BatchSink,
    ) -> Result<()>;
    fn query_scalar(&mut self, sql: &str) -> Result<Option<String>>;
    fn type_mappings(
        &mut self,
        query: &str,
        column_overrides: &ColumnOverrides,
    ) -> Result<Vec<TypeMapping>>;

    // Provided methods
    fn sample_pressure(&mut self) -> Option<u64> { ... }
    fn server_context(&mut self) -> Option<String> { ... }
}

Required Methods§

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fn export( &mut self, request: &ExportRequest<'_>, sink: &mut dyn BatchSink, ) -> Result<()>

Execute request.query and stream batches into sink.

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fn query_scalar(&mut self, sql: &str) -> Result<Option<String>>

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fn type_mappings( &mut self, query: &str, column_overrides: &ColumnOverrides, ) -> Result<Vec<TypeMapping>>

Return TypeMapping for every column in query without fetching rows.

Used by rivet check --type-report to show the full type provenance (source native type → RivetType → Arrow type → fidelity) before export. Implementations execute SELECT * FROM (...) AS _q LIMIT 0 so only server-side type metadata is transferred.

Provided Methods§

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fn sample_pressure(&mut self) -> Option<u64>

Sample a monotonic source-pressure counter for the OPT-2 concurrency governor (pipeline::chunked::exec).

Higher = more pressure. The governor compares successive samples (cur > prev ⇒ under pressure) — the same convention the adaptive batch-size loop already uses. Returns None when the engine can’t cheaply sample a pressure proxy, in which case the governor holds parallelism flat. Default: None.

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fn server_context(&mut self) -> Option<String>

A best-effort JSON snapshot of the source SERVER’s forensic context — version + the limits/session settings that shape failures (the statement-timeout that surfaces as ERROR 3024, the sql_mode/timezone that shape text rendering). Captured ONCE at run open onto the failed export_metrics row (server_context_json), so a post-mortem can explain a failure without re-querying a possibly-transient server. None when the engine can’t cheaply gather it; never fails the run.

Dyn Compatibility§

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors§