alamb commented on code in PR #16332:
URL: https://github.com/apache/datafusion/pull/16332#discussion_r2139195148
##########
datafusion-cli/src/functions.rs:
##########
@@ -460,3 +473,92 @@ impl TableFunctionImpl for ParquetMetadataFunc {
Ok(Arc::new(parquet_metadata))
}
}
+
+/// A table function that allows users to query files using glob patterns
+/// for example: SELECT * FROM glob('path/to/*/file.parquet')
+pub struct GlobFunc {
+ // we need the ctx here to get the schema from the listing table later
+ ctx: SessionContext,
+}
+
+impl std::fmt::Debug for GlobFunc {
+ fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+ f.debug_struct("GlobFunc")
+ .field("ctx", &"<SessionContext>")
+ .finish()
+ }
+}
+
+impl GlobFunc {
+ /// Create a new GlobFunc
+ pub fn new(ctx: SessionContext) -> Self {
+ Self { ctx }
+ }
+}
+
+fn as_utf8_literal<'a>(expr: &'a Expr, arg_name: &str) -> Result<&'a str> {
+ match expr {
+ Expr::Literal(ScalarValue::Utf8(Some(s)), _) => Ok(s),
Review Comment:
Minor: Maybe thus could use he `try_as_str` function (which would also
handle other literal types)
https://docs.rs/datafusion/latest/datafusion/scalar/enum.ScalarValue.html#method.try_as_str
##########
datafusion-cli/tests/sql/integration/glob_test.sql:
##########
@@ -0,0 +1,15 @@
+-- Test glob function with files available in CI
+-- Test 1: Single CSV file - verify basic functionality
+SELECT COUNT(*) AS cars_count FROM
glob('../datafusion/core/tests/data/cars.csv');
+
+-- Test 2: Data aggregation from CSV file - verify actual data reading
+SELECT car, COUNT(*) as count FROM
glob('../datafusion/core/tests/data/cars.csv') GROUP BY car ORDER BY car;
Review Comment:
I think another usecase that @robtandy had was "a list of multiple files"
-- like is there some way to select exactly two files? Something like
```sql
glob('[../datafusion/core/tests/data/cars.csv',
'../datafusion/core/tests/data/trucks.csv', ])
```
Perhaps 🤔
##########
datafusion-cli/tests/sql/integration/glob_test.sql:
##########
@@ -0,0 +1,15 @@
+-- Test glob function with files available in CI
+-- Test 1: Single CSV file - verify basic functionality
+SELECT COUNT(*) AS cars_count FROM
glob('../datafusion/core/tests/data/cars.csv');
+
+-- Test 2: Data aggregation from CSV file - verify actual data reading
+SELECT car, COUNT(*) as count FROM
glob('../datafusion/core/tests/data/cars.csv') GROUP BY car ORDER BY car;
+
+-- Test 3: JSON file with explicit format parameter - verify format
specification
+SELECT COUNT(*) AS json_count FROM
glob('../datafusion/core/tests/data/1.json', 'json');
+
+-- Test 4: Single specific CSV file - verify another CSV works
+SELECT COUNT(*) AS example_count FROM
glob('../datafusion/core/tests/data/example.csv');
+
+-- Test 5: Glob pattern with wildcard - test actual glob functionality
+SELECT COUNT(*) AS glob_pattern_count FROM
glob('../datafusion/core/tests/data/exa*.csv');
Review Comment:
Another possibility would be to intercept the `CREATE EXTERNAL TABLE`
command in `datafusion-cli` itself
For example, simliarly to how it peeks here:
https://github.com/apache/datafusion/blob/1d61f31d121632ca27c77c472cae7d604e9aa9d7/datafusion-cli/src/exec.rs#L357-L367
We could implement a special handler in datafusion-cli rather than use the
default one in SessionContext:
https://github.com/apache/datafusion/blob/1d61f31d121632ca27c77c472cae7d604e9aa9d7/datafusion/core/src/execution/context/mod.rs#L669-L672
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