[GitHub] [arrow-rs] tustvold commented on a diff in pull request #3209: Infer timestamps from CSV files

[GitBox <gi...@apache.org>]

tustvold commented on code in PR #3209:
URL: https://github.com/apache/arrow-rs/pull/3209#discussion_r1033541345


##########
arrow-csv/src/reader.rs:
##########
@@ -70,9 +70,11 @@ lazy_static! {
         .case_insensitive(true)
         .build()
         .unwrap();
-    static ref DATE_RE: Regex = Regex::new(r"^\d{4}-\d\d-\d\d$").unwrap();
+    static ref DATE32_RE: Regex = Regex::new(r"^\d{4}-\d\d-\d\d$").unwrap();
+    static ref DATE64_RE: Regex =
+        Regex::new(r"^\d{4}-\d\d-\d\d(T|\s)\d\d:\d\d:\d\d$").unwrap();
     static ref DATETIME_RE: Regex =
-        Regex::new(r"^\d{4}-\d\d-\d\dT\d\d:\d\d:\d\d$").unwrap();
+        Regex::new(r"^\d{4}-\d\d-\d\d(T|\s)\d\d:\d\d:\d\d(.\d{1,9})?$").unwrap();

Review Comment:
   ```suggestion
           Regex::new(r"^\d{4}-\d\d-\d\d[T ]\d\d:\d\d:\d\d(.\d{1,9})?$").unwrap();
   ```
   
   Or at the very least a non-capturing group. I also think it should probably be ` ` instead of `\s` as things like `\n` or `\t` I don't think would parse correctly.



##########
arrow-csv/src/reader.rs:
##########
@@ -90,10 +92,12 @@ fn infer_field_schema(string: &str, datetime_re: Option<Regex>) -> DataType {
         DataType::Float64
     } else if INTEGER_RE.is_match(string) {
         DataType::Int64
-    } else if datetime_re.is_match(string) {
-        DataType::Date64
-    } else if DATE_RE.is_match(string) {
+    } else if DATE32_RE.is_match(string) {

Review Comment:
   FWIW I created #3211 to track using a RegexSet here, as the current code is rather wasteful, perhaps something for a follow on PR?



##########
arrow-csv/src/reader.rs:
##########
@@ -70,9 +70,11 @@ lazy_static! {
         .case_insensitive(true)
         .build()
         .unwrap();
-    static ref DATE_RE: Regex = Regex::new(r"^\d{4}-\d\d-\d\d$").unwrap();
+    static ref DATE32_RE: Regex = Regex::new(r"^\d{4}-\d\d-\d\d$").unwrap();
+    static ref DATE64_RE: Regex =
+        Regex::new(r"^\d{4}-\d\d-\d\d(T|\s)\d\d:\d\d:\d\d$").unwrap();

Review Comment:
   ```suggestion
           Regex::new(r"^\d{4}-\d\d-\d\d[T ]\d\d:\d\d:\d\d$").unwrap();
   ```



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