Crate Configuration¶

This section contains information on how to configure builds of DataFusion in your Rust project. The Configuration Settings section lists options that control additional aspects DataFusion’s runtime behavior.

Using the nightly DataFusion builds¶

DataFusion changes are published to crates.io according to the release schedule

If you would like to use or test versions of the DataFusion code which are merged but not yet published, you can use Cargo’s [support for adding dependencies] directly to a GitHub branch:

datafusion = { git = "https://github.com/apache/datafusion", branch = "main"}

Also it works on the package level

datafusion-common = { git = "https://github.com/apache/datafusion", branch = "main", package = "datafusion-common"}

And with features

datafusion = { git = "https://github.com/apache/datafusion", branch = "main", default-features = false, features = ["unicode_expressions"] }

Optimizing Builds¶

Here are several suggestions to get the Rust compler to produce faster code when compiling DataFusion. Note that these changes may increase compile time and binary size.

Generate Code with CPU Specific Instructions¶

By default, the Rust compiler produces code that runs on a wide range of CPUs, but may not take advantage of all the features of your specific CPU (such as certain SIMD instructions). This is especially true for x86_64 CPUs, where the default target is x86_64-unknown-linux-gnu, which only guarantees support for the SSE2 instruction set. DataFusion can benefit from the more advanced instructions in the AVX2 and AVX512 to speed up operations like filtering, aggregation, and joins. To tell the Rust compiler to use these instructions, set the RUSTFLAGS environment variable to specify a more specific target CPU.

We recommend setting target-cpu or at least avx2, or preferably at least native (whatever the current CPU is). For example, to build and run DataFusion with optimizations for your current CPU:

RUSTFLAGS='-C target-cpu=native' cargo run --release

Enable Link Time Optimization / Single Codegen Unit¶

You can potentially improve your performance by compiling DataFusion into a single codegen unit which gives the Rust compiler more opportunity to optimize across crate boundaries. To do so, modify your projects’ Cargo.toml to include lto = true and codegen-units = 1 as shown below. Beware that using a single codegen unit significantly increases --release build times.

[profile.release]
lto = true
codegen-units = 1

Alternate Allocator: `snmalloc`¶

You can also use snmalloc-rs crate as the memory allocator for DataFusion to improve performance. To do so, add the dependency to your Cargo.toml as shown below.

[dependencies]
snmalloc-rs = "0.3"

Then, in main.rs. update the memory allocator with the below after your imports:

use datafusion::prelude::*;

#[global_allocator]
static ALLOC: snmalloc_rs::SnMalloc = snmalloc_rs::SnMalloc;

#[tokio::main]
async fn main() -> datafusion::error::Result<()> {
  Ok(())
}

Enable Backtraces¶

By default, Datafusion returns errors as a plain text message. You can enable more verbose details about the error, such as backtraces by enabling the backtrace feature to your Cargo.toml file like this:

datafusion = { version = "31.0.0", features = ["backtrace"]}

Set environment variables

RUST_BACKTRACE=1 ./target/debug/datafusion-cli
DataFusion CLI v31.0.0
> select row_numer() over (partition by a order by a) from (select 1 a);
Error during planning: Invalid function 'row_numer'.
Did you mean 'ROW_NUMBER'?

backtrace:    0: std::backtrace_rs::backtrace::libunwind::trace
             at /rustc/5680fa18feaa87f3ff04063800aec256c3d4b4be/library/std/src/../../backtrace/src/backtrace/libunwind.rs:93:5
   1: std::backtrace_rs::backtrace::trace_unsynchronized
             at /rustc/5680fa18feaa87f3ff04063800aec256c3d4b4be/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2: std::backtrace::Backtrace::create
             at /rustc/5680fa18feaa87f3ff04063800aec256c3d4b4be/library/std/src/backtrace.rs:332:13
   3: std::backtrace::Backtrace::capture
             at /rustc/5680fa18feaa87f3ff04063800aec256c3d4b4be/library/std/src/backtrace.rs:298:9
   4: datafusion_common::error::DataFusionError::get_back_trace
             at /datafusion/datafusion/common/src/error.rs:436:30
   5: datafusion_sql::expr::function::<impl datafusion_sql::planner::SqlToRel<S>>::sql_function_to_expr
   ............

The backtraces are useful when debugging code. If there is a test in datafusion/core/src/physical_planner.rs

#[tokio::test]
async fn test_get_backtrace_for_failed_code() -> Result<()> {
    let ctx = SessionContext::new();

    let sql = "
    select row_numer() over (partition by a order by a) from (select 1 a);
    ";

    let _ = ctx.sql(sql).await?.collect().await?;

    Ok(())
}

To obtain a backtrace:

cargo build --features=backtrace
RUST_BACKTRACE=1 cargo test --features=backtrace --package datafusion --lib -- physical_planner::tests::test_get_backtrace_for_failed_code --exact --nocapture

running 1 test
Error: Plan("Invalid function 'row_numer'.\nDid you mean 'ROW_NUMBER'?\n\nbacktrace:    0: std::backtrace_rs::backtrace::libunwind::trace\n             at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/../../backtrace/src/backtrace/libunwind.rs:105:5\n   1: std::backtrace_rs::backtrace::trace_unsynchronized\n...

Note: The backtrace wrapped into systems calls, so some steps on top of the backtrace can be ignored

To show the backtrace in a pretty-printed format use eprintln!("{e}");.

#[tokio::test]
async fn test_get_backtrace_for_failed_code() -> Result<()> {
    let ctx = SessionContext::new();

    let sql = "select row_numer() over (partition by a order by a) from (select 1 a);";

    let _ = match ctx.sql(sql).await {
        Ok(result) => result.show().await?,
        Err(e) => {
            eprintln!("{e}");
        }
    };

    Ok(())
}

Then run the test:

$ RUST_BACKTRACE=1 cargo test --features=backtrace --package datafusion --lib -- physical_planner::tests::test_get_backtrace_for_failed_code --exact --nocapture

running 1 test
Error during planning: Invalid function 'row_numer'.
Did you mean 'ROW_NUMBER'?

backtrace:    0: std::backtrace_rs::backtrace::libunwind::trace
             at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/../../backtrace/src/backtrace/libunwind.rs:105:5
   1: std::backtrace_rs::backtrace::trace_unsynchronized
             at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2: std::backtrace::Backtrace::create
             at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/backtrace.rs:331:13
   3: std::backtrace::Backtrace::capture
   ...

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