{"record":{"id":"b34d3e080346fd2a","repo":"pola-rs/polars","slug":"polars-maximum-length-reached-consider-compiling-with-bigidx","errorCode":null,"errorMessage":"Polars' maximum length reached. Consider compiling with 'bigidx' feature.","messagePattern":"Polars' maximum length reached\\. Consider compiling with 'bigidx' feature\\.","errorType":"panic","errorClass":null,"httpStatus":null,"severity":"critical","filePath":"crates/polars-core/src/chunked_array/ops/chunkops.rs","lineNumber":153,"sourceCode":"    /// Check if ChunkedArray is empty.\n    #[inline]\n    pub fn is_empty(&self) -> bool {\n        self.len() == 0\n    }\n\n    /// Compute the length\n    pub(crate) fn compute_len(&mut self) {\n        fn inner(chunks: &[ArrayRef]) -> usize {\n            match chunks.len() {\n                // fast path\n                1 => chunks[0].len(),\n                _ => chunks.iter().fold(0, |acc, arr| acc + arr.len()),\n            }\n        }\n        let len = inner(&self.chunks);\n        // Length limit is `IdxSize::MAX - 1`. We use `IdxSize::MAX` to indicate `NULL` in indexing.\n        if len >= (IdxSize::MAX as usize) && CHECK_LENGTH.get() {\n            panic!(\"{}\", LENGTH_LIMIT_MSG);\n        }\n        self.length = len;\n        self.null_count = self\n            .chunks\n            .iter()\n            .map(|arr| arr.null_count())\n            .sum::<usize>();\n    }\n\n    /// Rechunks this ChunkedArray, returning a new Cow::Owned ChunkedArray if it was\n    /// rechunked or simply a Cow::Borrowed of itself if it was already a single chunk.\n    pub fn rechunk(&self) -> Cow<'_, Self> {\n        match self.dtype() {\n            #[cfg(feature = \"object\")]\n            DataType::Object(_) => {\n                panic!(\"implementation error\")\n            },\n            _ => {","sourceCodeStart":135,"sourceCodeEnd":171,"githubUrl":"https://github.com/pola-rs/polars/blob/fe841f959ef4d2ceefc05a310d33ed7b1ab24e5e/crates/polars-core/src/chunked_array/ops/chunkops.rs#L135-L171","documentation":"IdxSize (the default index type) is 32-bit, so a ChunkedArray may hold at most IdxSize::MAX - 1 (~4.29 billion) elements; IdxSize::MAX is reserved to mark NULL indices. compute_len panics once the computed chunked length reaches that limit, telling the user to recompile with the bigidx feature (64-bit indices).","triggerScenarios":"Concatenating/extend/applying operations on chunks whose combined length reaches or exceeds u32::MAX (~4,294,967,295) rows while polars is compiled without the bigidx feature.","commonSituations":"Processing very large datasets (e.g. massive parquet/csv concatenations) with the default 32-bit build; hitting the limit after many concat/extend calls rather than in one operation.","solutions":["Switch to the bigidx feature: add `features = [\"bigidx\"]` to polars in Cargo.toml (the prebuilt polars-lts-cpu/polars wheels are already bigidx)","Split the work into partitions smaller than u32::MAX rows and process them separately","Reduce data by filtering/projecting before materializing the full column"],"exampleFix":"// before\npolars = \"0.x\"\n// after\npolars = { version = \"0.x\", features = [\"bigidx\"] }","handlingStrategy":"validation","validationCode":"const IDX_MAX: usize = u32::MAX as usize - 1;\nif total_rows >= IDX_MAX {\n    return Err(\"length exceeds 32-bit IdxSize; enable bigidx or partition data\");\n}","typeGuard":null,"tryCatchPattern":null,"preventionTips":["Compile with bigidx for workloads that may exceed ~4.29B rows","Check cumulative row counts before concat/extend of very large frames","Partition data by size in ETL pipelines"],"tags":["rust","polars","length-limit","bigidx"],"backgroundTag":"value-out-of-range","analyzedSha":"fe841f959ef4d2ceefc05a310d33ed7b1ab24e5e","analyzedAt":"2026-09-18T22:14:11.667Z","contentChangedAt":"2026-09-18T22:14:11.667Z","schemaVersion":2},"datasetVersion":"2026-09-23T08:17:48.524Z"}