houqp commented on a change in pull request #7210:
URL: https://github.com/apache/arrow/pull/7210#discussion_r427605427
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File path: rust/datafusion/src/execution/physical_plan/csv.rs
##########
@@ -71,15 +75,35 @@ impl CsvExec {
/// Create a new execution plan for reading a set of CSV files
pub fn try_new(
path: &str,
- schema: Arc<Schema>,
+ schema: Option<Arc<Schema>>,
has_header: bool,
+ delimiter: Option<u8>,
projection: Option<Vec<usize>>,
batch_size: usize,
) -> Result<Self> {
+ let schema = match schema {
+ Some(s) => s,
+ None => {
+ let mut filenames: Vec<String> = vec![];
+ common::build_file_list(path, &mut filenames, ".csv")?;
+ if filenames.is_empty() {
+ return Err(ExecutionError::General("No files
found".to_string()));
+ }
+
+ let f = File::open(&filenames[0])?;
Review comment:
yeah, there is no guarantee no matter what we do unless we read all the
entries. Even with max_inference, we can't guarantee the remaining rows will
confirm to the inferred schema.
the way i look at this is manually specify a schema if you want correctness
and performance. only use schema inference if you just want to get a quick and
dirty query up and running.
that said, i will try to change it to read all files instead of first one.
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