Neil Conway
c3f080774c
## Which issue does this PR close? - Closes #20302. ## Rationale for this change `translate()` is commonly invoked with constant values for its second and third arguments. We can take advantage of that to significantly optimize its performance by precomputing the translation lookup table, rather than recomputing it for every row. For ASCII-only inputs, we can further replace the hashmap lookup table with a fixed-size array that maps ASCII byte values directly. For scalar ASCII inputs, this yields roughly a 10x performance improvement. For scalar UTF8 inputs, the performance improvement is more like 50%, although less so for long strings. Along the way, add support for `translate()` on `LargeUtf8` input, along with an SLT test, and improve the docs. ## What changes are included in this PR? * Add a benchmark for scalar/constant input to translate * Add a missing test case * Improve translate() docs * Support translate() on LargeUtf8 input * Optimize translate() for scalar inputs by precomputing lookup hashmap * Optimize translate() for ASCII inputs by precomputing ASCII byte-wise lookup table ## Are these changes tested? Yes. Added an extra test case and did a bunch of benchmarking. ## Are there any user-facing changes? No. --------- Co-authored-by: Martin Grigorov <martin-g@users.noreply.github.com> Co-authored-by: Jeffrey Vo <jeffrey.vo.australia@gmail.com>
Apache DataFusion
DataFusion is an extensible query engine written in Rust that uses Apache Arrow as its in-memory format.
This crate provides libraries and binaries for developers building fast and feature-rich database and analytic systems, customized for particular workloads. See use cases for examples. The following related subprojects target end users:
- DataFusion Python offers a Python interface for SQL and DataFrame queries.
- DataFusion Comet is an accelerator for Apache Spark based on DataFusion.
"Out of the box," DataFusion offers SQL and DataFrame APIs, excellent performance, built-in support for CSV, Parquet, JSON, and Avro, extensive customization, and a great community.
DataFusion features a full query planner, a columnar, streaming, multi-threaded, vectorized execution engine, and partitioned data sources. You can customize DataFusion at almost all points including additional data sources, query languages, functions, custom operators and more. See the Architecture section for more details.
Here are links to important resources:
- Project Site
- Installation
- Rust Getting Started
- Rust DataFrame API
- Rust API docs
- Rust Examples
- Python DataFrame API
- Architecture
What can you do with this crate?
DataFusion is great for building projects such as domain-specific query engines, new database platforms and data pipelines, query languages and more. It lets you start quickly from a fully working engine, and then customize those features specific to your needs. See the list of known users.
Contributing to DataFusion
Please see the contributor guide and communication pages for more information.
Crate features
This crate has several features which can be specified in your Cargo.toml.
Default features:
nested_expressions: functions for working with nested types such asarray_to_stringcompression: reading files compressed withxz2,bzip2,flate2, andzstdcrypto_expressions: cryptographic functions such asmd5andsha256datetime_expressions: date and time functions such asto_timestampencoding_expressions:encodeanddecodefunctionsparquet: support for reading the Apache Parquet formatsql: support for SQL parsing and planningregex_expressions: regular expression functions, such asregexp_matchunicode_expressions: include Unicode-aware functions such ascharacter_lengthunparser: enables support to reverse LogicalPlans back into SQLrecursive_protection: uses recursive for stack overflow protection.
Optional features:
avro: support for reading the Apache Avro formatbacktrace: include backtrace information in error messagesparquet_encryption: support for using Parquet Modular Encryptionserde: enable arrow-schema'sserdefeature
DataFusion API Evolution and Deprecation Guidelines
Public methods in Apache DataFusion evolve over time: while we try to maintain a stable API, we also improve the API over time. As a result, we typically deprecate methods before removing them, according to the deprecation guidelines.
Dependencies and Cargo.lock
Following the guidance on committing Cargo.lock files, this project commits
its Cargo.lock file.
CI uses the committed Cargo.lock file, and dependencies are updated regularly
using Dependabot PRs.