Stream Crystal Reports XML at memory bandwidth.

crxml

Fast streaming parser for Crystal Reports XML exports.

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Quick start

from crxml import CrystalXMLSource

source = CrystalXMLSource("report.xml", row_tag="Details")

# Row iteration: yields dicts lazily
for row in source:
    print(row["invoice"], row["amount"])

# DataFrame (auto-routes to parallel engine)
df = source.to_dataframe()
print(df.head())

That is it. df is a pandas DataFrame with zero-copy ArrowDtype strings, built in under a second for a 100 MB file.

With pipeline stages fused into the Rust parse loop:

from crxml.stages import RenameFields, DropFields

pipeline = source | RenameFields({"f1": "invoice"}) | DropFields(["temp_id"])
df = pipeline.to_dataframe()

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Why crxml

Crystal Reports XML exports are deeply nested: <Group> wraps <GroupHeader> wraps <Section> wraps <Details> wraps <Field>/<Text>/<FormattedValue>/ <Value>/<TextValue>. Standard XML libraries (ElementTree, SAX, lxml) spend most of their CPU time descending into children you do not need.

crxml skips the nesting:

• The stream engine walks the XML once with quick-xml and yields flat dicts.
• The parallel engine memory-maps the file, splits it at row boundaries, and parses each chunk on its own thread into Arrow buffers directly (no dicts).
• Pipeline stages that rename, cast, drop, or filter fields execute in the Rust parse loop, before any Python object is created.

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Comparison: stream vs parallel

Task	stream	parallel
Row iteration	Yields dicts lazily	Arrow table first, then dicts (slower)
DataFrame output	Collects dicts, converts	Direct Arrow buffers, zero-copy
100 MB synthetic	2.3 s	0.21 s
533 MB real export	12.8 s	1.13 s
Peak RSS	~1.07 GB	~534 MB (file size, mmap)
Pipeline fusion	No (dict path)	Yes (Rust BuildPlan)

For files larger than RAM, add memory="500MB" to any engine for bounded mode: peak RSS tracks the budget, not the file.

Full benchmark details

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Install

pip install crxml

The columnar and parallel engines are included by default. For performance profiling counters: pip install -e . --config-settings=--features=profile.

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Features

Category	What crxml handles
Stream engine	Row-by-row XML parsing, yields dict[str, str], GIL-released batching
Columnar engine	Single-threaded Arrow table output, zero-copy string columns
Parallel engine	Multi-threaded (rayon), file split at row boundaries, off-GIL parse
Bounded mode	memory="500MB" splits into chunks; RSS independent of file size
Pipeline fusion	RenameFields, DropFields, CastTypes, FilterRows compile into Rust BuildPlan
mmap	Memory-maps input files (default, zero-copy)
prefault	MADV_WILLNEED vs MADV_SEQUENTIAL for RSS/speed trade-off
Arrow sinks	to_arrow(), to_pandas() (ArrowDtype), to_polars(), to_parquet()
Auto-dict encoding	auto_dict=True encodes low-cardinality string columns
Field typing	field_types={"amount": "float64"} coerces at parse time
Filter pushdown	filter={"field": "Status", "op": "==", "value": "Active"} in Rust
Correctness	All engines validated byte-identical against stream oracle (29 test cases + 465k-row real cross-check)

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Engine guide

Engine	When to use
stream	Row-by-row iteration (for row in source)
columnar	Single-threaded Arrow output
parallel	Fastest DataFrame output (default for files > 8 MB)
bounded	Files larger than RAM (memory="500MB" with any engine)

Pass engine= explicitly, or let auto select the best engine per call.

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Framework support

Framework	Integration
FastAPI / Starlette / Litestar	Parse in route handler, return DataFrame or Arrow table directly
Django / Flask	Call source.to_dataframe() in view; pass to template or response
Pandas / Polars	source.to_dataframe() / source.to_polars() for zero-copy analysis
Airflow / Prefect	Parse in task, write to parquet with source.to_parquet()
CLI / ETL scripts	Use to_csv() sink or iterate rows for line-by-line processing

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Documentation

Full docs at crxml.emiliano-go.com covering:

• All CrystalXMLSource parameters
• Pipeline stages and fusion rules
• Sink reference
• Batch iteration and parallel distribution
• Performance with phase breakdowns
• Architecture and correctness

License

MIT