Crate qvd 

qvd — High-performance Qlik QVD file library

Read, write, and convert Qlik QVD files with zero-copy roundtrip fidelity. First and only QVD crate on crates.io.

Features

• Read/Write QVD — byte-identical roundtrip (MD5 match on 20 real files up to 2.8 GB)
• Parquet ↔ QVD — bidirectional conversion with compression (snappy, zstd, gzip, lz4). Requires feature parquet_support.
• Arrow RecordBatch — convert QVD to/from Arrow for DataFusion, DuckDB, Polars integration. Requires feature parquet_support.
• DataFusion SQL — register QVD as a table, query with SQL. Requires feature datafusion_support.
• Streaming reader — read QVD in chunks without loading entire file into memory
• EXISTS() index — O(1) hash lookup, like Qlik’s EXISTS() function
• Python bindings — PyArrow, pandas, Polars via zero-copy Arrow bridge
• Zero dependencies for core read/write (Parquet/Arrow/DataFusion are optional)

Quick Start

Read and write QVD files

use qvd::{read_qvd_file, write_qvd_file};

let table = read_qvd_file("data.qvd").unwrap();
println!("Rows: {}, Cols: {}", table.num_rows(), table.num_cols());
println!("Columns: {:?}", table.column_names());

// Byte-identical roundtrip
write_qvd_file(&table, "output.qvd").unwrap();

EXISTS() — O(1) lookup

use qvd::{read_qvd_file, ExistsIndex, filter_rows_by_exists_fast};

let clients = read_qvd_file("clients.qvd").unwrap();
let index = ExistsIndex::from_column(&clients, "ClientID").unwrap();

assert!(index.exists("12345"));

let facts = read_qvd_file("facts.qvd").unwrap();
// col_idx = column index for "ClientID" in facts table
let col_idx = 0;
let filtered = filter_rows_by_exists_fast(&facts, col_idx, &index);

Streaming reader

use qvd::open_qvd_stream;

let mut reader = open_qvd_stream("huge_file.qvd").unwrap();
while let Some(chunk) = reader.next_chunk(65536).unwrap() {
    println!("Chunk: {} rows", chunk.num_rows);
}

Parquet ↔ QVD (feature parquet_support)

use qvd::{convert_parquet_to_qvd, convert_qvd_to_parquet, ParquetCompression};

convert_parquet_to_qvd("input.parquet", "output.qvd").unwrap();
convert_qvd_to_parquet("input.qvd", "output.parquet", ParquetCompression::Zstd).unwrap();

Arrow RecordBatch (feature parquet_support)

use qvd::{read_qvd_file, qvd_to_record_batch, record_batch_to_qvd};

let table = read_qvd_file("data.qvd").unwrap();
let batch = qvd_to_record_batch(&table).unwrap();
// Use with DataFusion, DuckDB, Polars...

DataFusion SQL (feature datafusion_support)

use datafusion::prelude::*;
use qvd::register_qvd;

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let ctx = SessionContext::new();
    register_qvd(&ctx, "sales", "sales.qvd")?;
    let df = ctx.sql("SELECT Region, SUM(Amount) FROM sales GROUP BY Region").await?;
    df.show().await?;
    Ok(())
}

Feature Flags

Feature	Dependencies	Description
(default)	none	Core QVD read/write, streaming, EXISTS
parquet_support	arrow, parquet, chrono	Parquet/Arrow ↔ QVD conversion
datafusion_support	+ datafusion, tokio	SQL queries on QVD via DataFusion
cli	+ clap	CLI binary qvd-cli
python	+ pyo3, arrow/pyarrow	Python bindings with PyArrow/pandas/Polars

Re-exports

pub use error::QvdError;

pub use error::QvdResult;

pub use header::QvdTableHeader;

pub use reader::read_qvd;

pub use reader::read_qvd_file;

pub use reader::QvdTable;

pub use writer::write_qvd;

pub use writer::write_qvd_file;

pub use writer::QvdTableBuilder;

pub use exists::ExistsIndex;

pub use exists::filter_rows_by_exists;

pub use exists::filter_rows_by_exists_fast;

pub use value::QvdSymbol;

pub use value::QvdValue;

pub use streaming::QvdStreamReader;

pub use streaming::QvdChunk;

pub use streaming::open_qvd_stream;

Modules

error

Error types for QVD operations.

exists

O(1) EXISTS() index and fast row filtering. See ExistsIndex.

header

QVD XML header parser and writer.

index

Bit-stuffed index table reader and writer.

reader

High-level QVD file reader. See read_qvd_file and QvdTable.

streaming

Streaming chunk-based QVD reader for memory-efficient processing of large files. See QvdStreamReader, open_qvd_stream, and QvdStreamReader::read_filtered for EXISTS()-style filtered reads that are 2.5x faster than Qlik Sense.

symbol

Binary symbol table reader and writer.

value

QVD value types: QvdSymbol and QvdValue.

writer

High-level QVD file writer and QvdTableBuilder for creating QVD files from scratch.