Method persist

benchmarks/src/sql_benchmark.rs:285–333

Calls run and persists results to disk as a CSV file. Requires that the benchmark defines a `result` or `result_query`. Registers the results in a memory table and writes them to disk with pipe delimiters and a header row. # Errors Returns an error if no results are available or if writing to the target path fails.

(&mut self, ctx: &SessionContext)

    /// Returns an error if no results are available or if writing to the
    /// target path fails.
    pub async fn persist(&mut self, ctx: &SessionContext) -> Result<()> {
        self.run(ctx, true).await?;

        // Check if we have result queries to persist for
        if self.result_queries.is_empty() {
            info!("No result paths to persist");
            return Ok(());
        }

        let results = self
            .last_results
            .as_ref()
            .expect("run should store last_results after successful execution");

        let query = &self.result_queries[0];
        let path = query.path.as_ref().ok_or_else(|| {
            exec_datafusion_err!(
                "Unable to persist results from query '{}', no result specified",
                query.query
            )
        })?;

        info!("Persisting results for query to {path}");

        let first_batch = results
            .first()
            .ok_or_else(|| exec_datafusion_err!("Results should be loaded"))?;

        let schema = first_batch.schema();
        let provider = MemTable::try_new(schema, vec![results.clone()])?;

        ctx.register_table("persist_data", Arc::new(provider))?;

        let df = ctx.table("persist_data").await?;
        df.write_csv(
            path,
            DataFrameWriteOptions::new(),
            Some(
                CsvOptions::default()
                    .with_delimiter(b'|')
                    .with_has_header(true),
            ),
        )
        .await?;

        ctx.deregister_table("persist_data")?;

        Ok(())
    }

    /// Verifies persisted results against expected values.
    ///