Remove data generation code from engine-specific bench binaries

.github/workflows/sql-benchmarks.yml

@@ -574,6 +574,7 @@ jobs:
         env:
           RUSTFLAGS: "-C target-cpu=native"
         run: |
+          # vx-bench prepare-data shells out to target/release_debug/data-gen.
           packages=(--bin data-gen --bin datafusion-bench --bin duckdb-bench)
           if [ "${{ inputs.mode }}" != "pr" ]; then
             packages+=(--bin lance-bench)

benchmarks/datafusion-bench/src/main.rs

@@ -31,16 +31,15 @@ use vortex::io::filesystem::FileSystemRef;
 use vortex::scan::DataSourceRef;
 use vortex_bench::Benchmark;
 use vortex_bench::BenchmarkArg;
-use vortex_bench::CompactionStrategy;
 use vortex_bench::Engine;
 use vortex_bench::Format;
 use vortex_bench::Opt;
 use vortex_bench::Opts;
 use vortex_bench::SESSION;
-use vortex_bench::conversions::convert_parquet_directory_to_vortex;
 use vortex_bench::create_benchmark;
 use vortex_bench::create_output_writer;
 use vortex_bench::display::DisplayFormat;
+use vortex_bench::require_prepared_data;
 use vortex_bench::runner::BenchmarkMode;
 use vortex_bench::runner::BenchmarkQueryResult;
 use vortex_bench::runner::SqlBenchmarkRunner;
@@ -131,29 +130,7 @@ async fn main() -> anyhow::Result<()> {
         args.exclude_queries.as_ref(),
     );
 
-    // Generate Vortex files from Parquet for any Vortex formats requested
-    if benchmark.data_url().scheme() == "file" {
-        benchmark.generate_base_data().await?;
-
-        let base_path = benchmark
-            .data_url()
-            .to_file_path()
-            .map_err(|_| anyhow::anyhow!("Invalid file URL: {}", benchmark.data_url()))?;
-
-        for format in args.formats.iter() {
-            match format {
-                Format::OnDiskVortex => {
-                    convert_parquet_directory_to_vortex(&base_path, CompactionStrategy::Default)
-                        .await?;
-                }
-                Format::VortexCompact => {
-                    convert_parquet_directory_to_vortex(&base_path, CompactionStrategy::Compact)
-                        .await?;
-                }
-                _ => {}
-            }
-        }
-    }
+    require_prepared_data(&*benchmark, &args.formats)?;
 
     let benchmark_name = benchmark.dataset().to_string();
 

benchmarks/duckdb-bench/src/lib.rs

@@ -51,13 +51,38 @@ impl DuckClient {
             format!("{name}/{format}/", name = benchmark.dataset_name()).to_data_path()
         };
         let dir = base_path.join(format.name());
-        std::fs::create_dir_all(&dir)?;
         let db_path = dir.join("duckdb.db");
 
+        if format == Format::OnDiskDuckDB && data_url.scheme() != "file" {
+            anyhow::bail!("DuckDB format requires local data prepared by data-gen");
+        }
+
+        if format == Format::OnDiskDuckDB {
+            if !db_path.exists() {
+                anyhow::bail!(
+                    "prepared DuckDB database is missing at {}. Generate it with \
+                     `vx-bench prepare-data {} --formats-json '[\"duckdb\"]'` or \
+                     `cargo run --bin data-gen -- {} --formats duckdb` using the same --opt values.",
+                    db_path.display(),
+                    benchmark.dataset_name(),
+                    benchmark.dataset_name(),
+                );
+            }
+        } else {
+            std::fs::create_dir_all(&dir)?;
+        }
+
         tracing::info!(db_path = %db_path.display(), "Opening DuckDB");
 
         if delete_database && db_path.exists() {
-            std::fs::remove_file(&db_path)?;
+            if format == Format::OnDiskDuckDB {
+                tracing::info!(
+                    db_path = %db_path.display(),
+                    "Keeping prepared DuckDB format database"
+                );
+            } else {
+                std::fs::remove_file(&db_path)?;
+            }
         }
 
         let (db, connection) = Self::open_and_setup_database(Some(db_path.clone()), threads)?;
@@ -147,9 +172,14 @@ impl DuckClient {
         benchmark: &B,
         file_format: Format,
     ) -> Result<()> {
+        if file_format == Format::OnDiskDuckDB {
+            // Native DuckDB data is materialized by data-gen. The opened database already
+            // contains benchmark tables, so there is nothing to register here.
+            return Ok(());
+        }
+
         let object_type = match file_format {
             Format::Parquet | Format::OnDiskVortex | Format::VortexCompact => "VIEW",
-            Format::OnDiskDuckDB => "TABLE",
             Format::Lance => {
                 anyhow::bail!(
                     "Lance format is not supported for DuckDB engine. \
@@ -159,11 +189,7 @@ impl DuckClient {
             format => anyhow::bail!("Format {format} isn't supported for DuckDB"),
         };
 
-        // DuckDB loads from parquet for OnDiskDuckDB format
-        let load_format = match file_format {
-            Format::Parquet | Format::OnDiskDuckDB => Format::Parquet,
-            f => f,
-        };
+        let load_format = file_format;
 
         // Get the base URL for the format's data directory
         let format_url = benchmark.format_path(load_format, benchmark.data_url())?;

benchmarks/duckdb-bench/src/main.rs

@@ -8,18 +8,16 @@ use std::path::PathBuf;
 use clap::Parser;
 use clap::value_parser;
 use duckdb_bench::DuckClient;
-use tokio::runtime::Runtime;
 use vortex::metrics::tracing::set_global_labels;
 use vortex_bench::BenchmarkArg;
-use vortex_bench::CompactionStrategy;
 use vortex_bench::Engine;
 use vortex_bench::Format;
 use vortex_bench::Opt;
 use vortex_bench::Opts;
-use vortex_bench::conversions::convert_parquet_directory_to_vortex;
 use vortex_bench::create_benchmark;
 use vortex_bench::create_output_writer;
 use vortex_bench::display::DisplayFormat;
+use vortex_bench::require_prepared_data;
 use vortex_bench::runner::BenchmarkMode;
 use vortex_bench::runner::SqlBenchmarkRunner;
 use vortex_bench::runner::filter_queries;
@@ -110,43 +108,7 @@ fn main() -> anyhow::Result<()> {
         anyhow::bail!("provide a format with --formats");
     }
 
-    // Generate Vortex files from Parquet for any Vortex formats requested
-    if benchmark.data_url().scheme() == "file" {
-        // This is ugly, but otherwise some complicated async interaction might result in a deadlock
-        let runtime = Runtime::new()?;
-
-        runtime.block_on(async {
-            benchmark.generate_base_data().await?;
-
-            let base_path = benchmark
-                .data_url()
-                .to_file_path()
-                .map_err(|_| anyhow::anyhow!("Invalid file URL: {}", benchmark.data_url()))?;
-
-            for format in args.formats.iter().copied() {
-                match format {
-                    Format::OnDiskVortex => {
-                        convert_parquet_directory_to_vortex(
-                            &base_path,
-                            CompactionStrategy::Default,
-                        )
-                        .await?;
-                    }
-                    Format::VortexCompact => {
-                        convert_parquet_directory_to_vortex(
-                            &base_path,
-                            CompactionStrategy::Compact,
-                        )
-                        .await?;
-                    }
-                    // OnDiskDuckDB tables are created during register_tables by loading from Parquet
-                    _ => {}
-                }
-            }
-
-            anyhow::Ok(())
-        })?;
-    }
+    require_prepared_data(&*benchmark, &args.formats)?;
 
     let mut runner = SqlBenchmarkRunner::new(
         &*benchmark,

vortex-bench/src/benchmark.rs

@@ -36,8 +36,8 @@ pub trait Benchmark: Send + Sync {
     /// This is the canonical source data that can be converted to other formats.
     /// This should be idempotent - safe to call multiple times.
     ///
-    /// Format-specific benchmark binaries (like lance-bench, datafusion-bench, duckdb-bench) should
-    /// call this method to ensure base data exists, then perform their own format conversion.
+    /// The `data-gen` binary calls this method before creating requested derived formats.
+    /// Engine-specific benchmark binaries should only run against prepared data.
     async fn generate_base_data(&self) -> anyhow::Result<()>;
 
     /// Get expected row counts for validation (optional)

vortex-bench/src/lib.rs

@@ -245,6 +245,66 @@ impl CompactionStrategy {
     }
 }
 
+/// Verify that local data has already been prepared for the requested benchmark formats.
+///
+/// Engine-specific benchmark binaries call this before running queries. Data generation itself
+/// belongs to the `data-gen` binary.
+pub fn require_prepared_data<B>(benchmark: &B, formats: &[Format]) -> anyhow::Result<()>
+where
+    B: Benchmark + ?Sized,
+{
+    if benchmark.data_url().scheme() != "file" {
+        return Ok(());
+    }
+
+    let base_path = benchmark
+        .data_url()
+        .to_file_path()
+        .map_err(|_| anyhow::anyhow!("Invalid file URL: {}", benchmark.data_url()))?;
+
+    let mut missing = Vec::new();
+    for format in formats.iter().copied().unique() {
+        let required_path = match format {
+            Format::Arrow | Format::Parquet => base_path.join(Format::Parquet.name()),
+            Format::OnDiskVortex => base_path.join(Format::OnDiskVortex.name()),
+            Format::VortexCompact => base_path.join(Format::VortexCompact.name()),
+            Format::OnDiskDuckDB => base_path
+                .join(Format::OnDiskDuckDB.name())
+                .join("duckdb.db"),
+            format => base_path.join(format.name()),
+        };
+
+        if !required_path.exists() {
+            missing.push((format, required_path));
+        }
+    }
+
+    if missing.is_empty() {
+        return Ok(());
+    }
+
+    let missing_data = missing
+        .iter()
+        .map(|(format, path)| format!("{format} ({})", path.display()))
+        .join(", ");
+    let requested_formats = formats
+        .iter()
+        .copied()
+        .unique()
+        .map(|format| format!("\"{format}\""))
+        .join(",");
+
+    anyhow::bail!(
+        "prepared data is missing for {}: {missing_data}. Generate it first with \
+         `vx-bench prepare-data {} --formats-json '[{requested_formats}]'` or \
+         `cargo run --bin data-gen -- {} --formats {}` using the same --opt values.",
+        benchmark.dataset_display(),
+        benchmark.dataset_name(),
+        benchmark.dataset_name(),
+        formats.iter().copied().unique().join(","),
+    );
+}
+
 /// CLI argument for selecting which benchmark to run.
 #[derive(clap::ValueEnum, Clone, Copy)]
 pub enum BenchmarkArg {