Parallel csv writer

polars/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "polars"
-version = "0.22.5"
+version = "0.22.6"
 authors = ["ritchie46 <ritchie46@gmail.com>"]
 edition = "2021"
 keywords = ["dataframe", "query-engine", "arrow"]
@@ -242,11 +242,11 @@ bench = [
 ]
 
 [dependencies]
-polars-core = { version = "0.22.5", path = "./polars-core", features = ["docs", "private"], default-features = false }
-polars-io = { version = "0.22.5", path = "./polars-io", features = ["private"], default-features = false, optional = true }
-polars-lazy = { version = "0.22.5", path = "./polars-lazy", features = ["private"], default-features = false, optional = true }
-polars-ops = { version = "0.22.5", path = "./polars-ops" }
-polars-time = { version = "0.22.5", path = "./polars-time", default-features = false, optional = true }
+polars-core = { version = "0.22.6", path = "./polars-core", features = ["docs", "private"], default-features = false }
+polars-io = { version = "0.22.6", path = "./polars-io", features = ["private"], default-features = false, optional = true }
+polars-lazy = { version = "0.22.6", path = "./polars-lazy", features = ["private"], default-features = false, optional = true }
+polars-ops = { version = "0.22.6", path = "./polars-ops" }
+polars-time = { version = "0.22.6", path = "./polars-time", default-features = false, optional = true }
 
 [dev-dependencies]
 ahash = "0.7"

polars/polars-arrow/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "polars-arrow"
-version = "0.22.5"
+version = "0.22.6"
 authors = ["ritchie46 <ritchie46@gmail.com>"]
 edition = "2021"
 license = "MIT"

polars/polars-core/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "polars-core"
-version = "0.22.5"
+version = "0.22.6"
 authors = ["ritchie46 <ritchie46@gmail.com>"]
 edition = "2021"
 license = "MIT"
@@ -158,8 +158,8 @@ jsonpath_lib = { version = "0.3.0", optional = true, git = "https://github.com/r
 ndarray = { version = "0.15", optional = true, default_features = false }
 num = "^0.4"
 once_cell = "1"
-polars-arrow = { version = "0.22.5", path = "../polars-arrow", features = ["compute"] }
-polars-utils = { version = "0.22.5", path = "../polars-utils" }
+polars-arrow = { version = "0.22.6", path = "../polars-arrow", features = ["compute"] }
+polars-utils = { version = "0.22.6", path = "../polars-utils" }
 rand = { version = "0.8", optional = true, features = ["small_rng", "std"] }
 rand_distr = { version = "0.4", optional = true }
 rayon = "1.5"

polars/polars-core/src/chunked_array/ops/any_value.rs

@@ -8,6 +8,7 @@ pub(crate) unsafe fn arr_to_any_value<'a>(
     idx: usize,
     dtype: &'a DataType,
 ) -> AnyValue<'a> {
+    debug_assert!(idx < arr.len());
     if arr.is_null(idx) {
         return AnyValue::Null;
     }

polars/polars-core/src/series/iterator.rs

@@ -94,11 +94,11 @@ impl<'a> Iterator for SeriesIter<'a> {
 
     fn next(&mut self) -> Option<Self::Item> {
         let idx = self.idx;
-        self.idx += 1;
 
         if idx == self.len {
             None
         } else {
+            self.idx += 1;
             unsafe { Some(arr_to_any_value(self.arr, idx, self.dtype)) }
         }
     }

polars/polars-core/src/series/mod.rs

@@ -33,6 +33,7 @@ use std::hash::{Hash, Hasher};
 use std::ops::Deref;
 use std::sync::Arc;
 
+pub use iterator::SeriesIter;
 pub use series_trait::IsSorted;
 
 /// # Series

polars/polars-io/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "polars-io"
-version = "0.22.5"
+version = "0.22.6"
 authors = ["ritchie46 <ritchie46@gmail.com>"]
 edition = "2021"
 license = "MIT"
@@ -23,7 +23,7 @@ dtype-datetime = ["polars-core/dtype-datetime", "polars-core/temporal", "polars-
 dtype-date = ["polars-core/dtype-date", "polars-time/dtype-date"]
 dtype-time = ["polars-core/dtype-time", "polars-core/temporal", "polars-time/dtype-time"]
 dtype-categorical = ["polars-core/dtype-categorical"]
-csv-file = ["csv-core", "memmap", "lexical", "arrow/io_csv_write"]
+csv-file = ["csv-core", "memmap", "lexical", "polars-core/rows", "lexical-core"]
 fmt = ["polars-core/fmt"]
 decompress = ["flate2/miniz_oxide"]
 decompress-fast = ["flate2/zlib-ng-compat"]
@@ -43,14 +43,15 @@ csv-core = { version = "0.1.10", optional = true }
 dirs = "4.0"
 flate2 = { version = "1", optional = true, default-features = false }
 lexical = { version = "6", optional = true, default-features = false, features = ["std", "parse-floats", "parse-integers"] }
+lexical-core = { version = "0.8", optional = true }
 memchr = "2.4"
 memmap = { package = "memmap2", version = "0.5.2", optional = true }
 num = "^0.4"
 once_cell = "1"
-polars-arrow = { version = "0.22.5", path = "../polars-arrow" }
-polars-core = { version = "0.22.5", path = "../polars-core", features = ["private"], default-features = false }
-polars-time = { version = "0.22.5", path = "../polars-time", features = ["private"], default-features = false, optional = true }
-polars-utils = { version = "0.22.5", path = "../polars-utils" }
+polars-arrow = { version = "0.22.6", path = "../polars-arrow" }
+polars-core = { version = "0.22.6", path = "../polars-core", features = ["private"], default-features = false }
+polars-time = { version = "0.22.6", path = "../polars-time", features = ["private"], default-features = false, optional = true }
+polars-utils = { version = "0.22.6", path = "../polars-utils" }
 rayon = "1.5"
 regex = "1.5"
 serde = { version = "1", features = ["derive"], optional = true }

polars/polars-io/src/csv.rs

@@ -47,7 +47,7 @@ use crate::mmap::MmapBytesReader;
 use crate::predicates::PhysicalIoExpr;
 use crate::utils::resolve_homedir;
 use crate::{RowCount, SerReader, SerWriter};
-pub use arrow::io::csv::write;
+
 use polars_core::prelude::*;
 #[cfg(feature = "temporal")]
 use polars_time::prelude::*;
@@ -60,14 +60,18 @@ use std::fs::File;
 use std::io::Write;
 use std::path::PathBuf;
 
+use super::csv_core::write;
+
 /// Write a DataFrame to csv.
+///
+/// Don't use a `Buffered` writer, the `CsvWriter` internally already buffers writes.
 #[must_use]
 pub struct CsvWriter<W: Write> {
     /// File or Stream handler
     buffer: W,
-    /// arrow specific options
     options: write::SerializeOptions,
     header: bool,
+    batch_size: usize,
 }
 
 impl<W> SerWriter<W> for CsvWriter<W>
@@ -77,29 +81,26 @@ where
     fn new(buffer: W) -> Self {
         // 9f: all nanoseconds
         let options = write::SerializeOptions {
-            time64_format: Some("%T%.9f".to_string()),
-            timestamp_format: Some("%FT%H:%M:%S.%9f".to_string()),
+            time_format: Some("%T%.9f".to_string()),
+            datetime_format: Some("%FT%H:%M:%S.%9f".to_string()),
             ..Default::default()
         };
 
         CsvWriter {
             buffer,
             options,
             header: true,
+            batch_size: 1024,
         }
     }
 
     fn finish(&mut self, df: &mut DataFrame) -> Result<()> {
-        df.rechunk();
+        df.as_single_chunk_par();
         let names = df.get_column_names();
-        let iter = df.iter_chunks();
         if self.header {
             write::write_header(&mut self.buffer, &names, &self.options)?;
         }
-        for batch in iter {
-            write::write_chunk(&mut self.buffer, &batch, &self.options)?;
-        }
-        Ok(())
+        write::write(&mut self.buffer, df, self.batch_size, &self.options)
     }
 }
 
@@ -119,22 +120,26 @@ where
         self
     }
 
+    pub fn with_batch_size(mut self, batch_size: usize) -> Self {
+        self.batch_size = batch_size;
+        self
+    }
+
     /// Set the CSV file's date format
     pub fn with_date_format(mut self, format: Option<String>) -> Self {
-        self.options.date32_format = format;
+        self.options.date_format = format;
         self
     }
 
     /// Set the CSV file's time format
     pub fn with_time_format(mut self, format: Option<String>) -> Self {
-        self.options.time32_format = format.clone();
-        self.options.time64_format = format;
+        self.options.time_format = format;
         self
     }
 
     /// Set the CSV file's timestamp format array in
-    pub fn with_timestamp_format(mut self, format: Option<String>) -> Self {
-        self.options.timestamp_format = format;
+    pub fn with_datetime(mut self, format: Option<String>) -> Self {
+        self.options.datetime_format = format;
         self
     }
 

polars/polars-io/src/csv_core/csv.rs

@@ -9,6 +9,7 @@ use crate::RowCount;
 use polars_arrow::array::*;
 use polars_core::utils::accumulate_dataframes_vertical;
 use polars_core::{prelude::*, POOL};
+#[cfg(feature = "polars-time")]
 use polars_time::prelude::*;
 use polars_utils::flatten;
 use rayon::prelude::*;

polars/polars-io/src/csv_core/mod.rs

@@ -6,3 +6,4 @@ pub(crate) mod parser;
 pub(crate) mod utils;
 #[cfg(feature = "private")]
 pub mod utils;
+pub(super) mod write;

polars/polars-io/src/csv_core/utils.rs

@@ -9,7 +9,9 @@ use crate::prelude::NullValues;
 use once_cell::sync::Lazy;
 use polars_core::datatypes::PlHashSet;
 use polars_core::prelude::*;
+#[cfg(feature = "polars-time")]
 use polars_time::chunkedarray::utf8::infer as date_infer;
+#[cfg(feature = "polars-time")]
 use polars_time::prelude::utf8::Pattern;
 use regex::{Regex, RegexBuilder};
 use std::borrow::Cow;
@@ -94,12 +96,19 @@ fn infer_field_schema(string: &str, parse_dates: bool) -> DataType {
     // Utf8 for them
     if string.starts_with('"') {
         if parse_dates {
-            match date_infer::infer_pattern_single(&string[1..string.len() - 1]) {
-                Some(Pattern::DatetimeYMD | Pattern::DatetimeDMY) => {
-                    DataType::Datetime(TimeUnit::Microseconds, None)
+            #[cfg(feature = "polars-time")]
+            {
+                match date_infer::infer_pattern_single(&string[1..string.len() - 1]) {
+                    Some(Pattern::DatetimeYMD | Pattern::DatetimeDMY) => {
+                        DataType::Datetime(TimeUnit::Microseconds, None)
+                    }
+                    Some(Pattern::DateYMD | Pattern::DateDMY) => DataType::Date,
+                    None => DataType::Utf8,
                 }
-                Some(Pattern::DateYMD | Pattern::DateDMY) => DataType::Date,
-                None => DataType::Utf8,
+            }
+            #[cfg(not(feature = "polars-time"))]
+            {
+                panic!("activate one of {{'dtype-date', 'dtype-datetime', dtype-time'}} features")
             }
         } else {
             DataType::Utf8
@@ -113,12 +122,19 @@ fn infer_field_schema(string: &str, parse_dates: bool) -> DataType {
     } else if INTEGER_RE.is_match(string) {
         DataType::Int64
     } else if parse_dates {
-        match date_infer::infer_pattern_single(string) {
-            Some(Pattern::DatetimeYMD | Pattern::DatetimeDMY) => {
-                DataType::Datetime(TimeUnit::Microseconds, None)
+        #[cfg(feature = "polars-time")]
+        {
+            match date_infer::infer_pattern_single(string) {
+                Some(Pattern::DatetimeYMD | Pattern::DatetimeDMY) => {
+                    DataType::Datetime(TimeUnit::Microseconds, None)
+                }
+                Some(Pattern::DateYMD | Pattern::DateDMY) => DataType::Date,
+                None => DataType::Utf8,
             }
-            Some(Pattern::DateYMD | Pattern::DateDMY) => DataType::Date,
-            None => DataType::Utf8,
+        }
+        #[cfg(not(feature = "polars-time"))]
+        {
+            panic!("activate one of {{'dtype-date', 'dtype-datetime', dtype-time'}} features")
         }
     } else {
         DataType::Utf8