tustvold commented on code in PR #3746:
URL: https://github.com/apache/arrow-rs/pull/3746#discussion_r1114894599
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arrow-csv/src/reader/mod.rs:
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@@ -62,44 +61,68 @@ use crate::reader::records::{RecordDecoder, StringRecords};
use csv::StringRecord;
lazy_static! {
+ /// Order should match [`InferredDataType`]
static ref REGEX_SET: RegexSet = RegexSet::new([
r"(?i)^(true)$|^(false)$(?-i)", //BOOLEAN
- r"^-?((\d*\.\d+|\d+\.\d*)([eE]-?\d+)?|\d+([eE]-?\d+))$", //DECIMAL
r"^-?(\d+)$", //INTEGER
+ r"^-?((\d*\.\d+|\d+\.\d*)([eE]-?\d+)?|\d+([eE]-?\d+))$", //DECIMAL
r"^\d{4}-\d\d-\d\d$", //DATE32
- r"^\d{4}-\d\d-\d\d[T ]\d\d:\d\d:\d\d$", //DATE64
+ r"^\d{4}-\d\d-\d\d[T ]\d\d:\d\d:\d\d$", //Timestamp(Second)
+ r"^\d{4}-\d\d-\d\d[T ]\d\d:\d\d:\d\d.\d{1,3}$",
//Timestamp(Millisecond)
+ r"^\d{4}-\d\d-\d\d[T ]\d\d:\d\d:\d\d.\d{1,6}$",
//Timestamp(Microsecond)
+ r"^\d{4}-\d\d-\d\d[T ]\d\d:\d\d:\d\d.\d{1,9}$", //Timestamp(Nanosecond)
]).unwrap();
- //The order should match with REGEX_SET
- static ref MATCH_DATA_TYPE: Vec<DataType> = vec![
- DataType::Boolean,
- DataType::Float64,
- DataType::Int64,
- DataType::Date32,
- DataType::Date64,
- ];
static ref PARSE_DECIMAL_RE: Regex =
Regex::new(r"^-?(\d+\.?\d*|\d*\.?\d+)$").unwrap();
- static ref DATETIME_RE: Regex =
- Regex::new(r"^\d{4}-\d\d-\d\d[T ]\d\d:\d\d:\d\d\.\d{1,9}$").unwrap();
}
-/// Infer the data type of a record
-fn infer_field_schema(string: &str, datetime_re: Option<Regex>) -> DataType {
- // when quoting is enabled in the reader, these quotes aren't escaped, we
default to
- // Utf8 for them
- if string.starts_with('"') {
- return DataType::Utf8;
- }
- let matches = REGEX_SET.matches(string).into_iter().next();
- // match regex in a particular order
- match matches {
- Some(ix) => MATCH_DATA_TYPE[ix].clone(),
- None => {
- let datetime_re = datetime_re.unwrap_or_else(||
DATETIME_RE.clone());
- if datetime_re.is_match(string) {
- DataType::Timestamp(TimeUnit::Nanosecond, None)
- } else {
- DataType::Utf8
+#[derive(Default, Copy, Clone)]
+struct InferredDataType {
Review Comment:
This logic should be significantly faster as an added bonus
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