feat: Experimental unity catalog client

.github/workflows/test-pyodide.yml

@@ -39,7 +39,7 @@ jobs:
 
       - name: Disable incompatible features
         env:
-            FEATURES: parquet|async|json|extract_jsonpath|cloud|polars_cloud|tokio|clipboard|decompress|new_streaming
+          FEATURES: parquet|async|json|extract_jsonpath|catalog|cloud|polars_cloud|tokio|clipboard|decompress|new_streaming
         run: |
           sed -i 's/^  "json",$/  "serde_json",/' crates/polars-python/Cargo.toml
           sed -E -i "/^  \"(${FEATURES})\",$/d" crates/polars-python/Cargo.toml py-polars/Cargo.toml

crates/polars-io/Cargo.toml

@@ -46,6 +46,7 @@ serde = { workspace = true, features = ["rc"], optional = true }
 serde_json = { version = "1", optional = true }
 simd-json = { workspace = true, optional = true }
 simdutf8 = { workspace = true, optional = true }
+strum_macros = { workspace = true, optional = true }
 tokio = { workspace = true, features = ["fs", "net", "rt-multi-thread", "time", "sync"], optional = true }
 tokio-util = { workspace = true, features = ["io", "io-util"], optional = true }
 url = { workspace = true, optional = true }
@@ -59,6 +60,7 @@ home = "0.5.4"
 tempfile = "3"
 
 [features]
+catalog = ["cloud", "serde", "reqwest", "futures", "strum_macros"]
 default = ["decompress"]
 # support for arrows json parsing
 json = [

crates/polars-io/src/catalog/mod.rs

@@ -0,0 +1,2 @@
+pub mod schema;
+pub mod unity;

crates/polars-io/src/catalog/schema.rs

@@ -0,0 +1,265 @@
+use polars_core::prelude::{DataType, Field};
+use polars_core::schema::{Schema, SchemaRef};
+use polars_error::{polars_bail, polars_err, PolarsResult};
+use polars_utils::pl_str::PlSmallStr;
+
+use super::unity::models::TableInfo;
+
+/// Returns `(schema, hive_schema)`
+pub fn table_info_to_schemas(
+    table_info: &TableInfo,
+) -> PolarsResult<(Option<SchemaRef>, Option<SchemaRef>)> {
+    let Some(columns) = table_info.columns.as_deref() else {
+        return Ok((None, None));
+    };
+
+    let mut schema = Schema::default();
+    let mut hive_schema = Schema::default();
+
+    for (i, col) in columns.iter().enumerate() {
+        let dtype = parse_type_str(&col.type_text)?;
+
+        if let Some(position) = col.position {
+            if usize::try_from(position).unwrap() != i {
+                polars_bail!(
+                    ComputeError:
+                    "not yet supported: position was not ordered"
+                )
+            }
+        }
+
+        if let Some(i) = col.partition_index {
+            if usize::try_from(i).unwrap() != hive_schema.len() {
+                polars_bail!(
+                    ComputeError:
+                    "not yet supported: partition_index was not ordered"
+                )
+            }
+
+            hive_schema.extend([Field::new(col.name.as_str().into(), dtype)]);
+        } else {
+            schema.extend([Field::new(col.name.as_str().into(), dtype)])
+        }
+    }
+
+    Ok((
+        Some(schema.into()),
+        Some(hive_schema)
+            .filter(|x| !x.is_empty())
+            .map(|x| x.into()),
+    ))
+}
+
+/// Parse a type string from a catalog API response.
+///
+/// References:
+/// * https://spark.apache.org/docs/latest/sql-ref-datatypes.html
+/// * https://docs.databricks.com/api/workspace/tables/get
+/// * https://docs.databricks.com/en/sql/language-manual/sql-ref-datatypes.html
+///
+/// Note: `type_precision` and `type_scale` in the API response are defined as supplementary data to
+/// the `type_text`, but from testing they aren't actually used - e.g. a decimal type would have a
+/// `type_text` of `decimal(18, 2)`
+fn parse_type_str(type_text: &str) -> PolarsResult<DataType> {
+    use DataType::*;
+
+    let dtype = match type_text {
+        "boolean" => Boolean,
+
+        "byte" | "tinyint" => Int8,
+        "short" | "smallint" => Int16,
+        "int" | "integer" => Int32,
+        "long" | "bigint" => Int64,
+
+        "float" | "real" => Float32,
+        "double" => Float64,
+
+        "date" => Date,
+        "timestamp" | "timestamp_ltz" | "timestamp_ntz" => {
+            Datetime(polars_core::prelude::TimeUnit::Nanoseconds, None)
+        },
+
+        "string" => String,
+        "binary" => Binary,
+
+        "null" | "void" => Null,
+
+        v => {
+            if v.starts_with("decimal") {
+                // e.g. decimal(38,18)
+                (|| {
+                    let (precision, scale) = v
+                        .get(7..)?
+                        .strip_prefix('(')?
+                        .strip_suffix(')')?
+                        .split_once(',')?;
+                    let precision: usize = precision.parse().ok()?;
+                    let scale: usize = scale.parse().ok()?;
+
+                    Some(DataType::Decimal(Some(precision), Some(scale)))
+                })()
+                .ok_or_else(|| {
+                    polars_err!(
+                        ComputeError:
+                        "type format did not match decimal(int,int): {}",
+                        v
+                    )
+                })?
+            } else if v.starts_with("array") {
+                // e.g. array<int>
+                DataType::List(Box::new(parse_type_str(extract_angle_brackets_inner(
+                    v, "array",
+                )?)?))
+            } else if v.starts_with("struct") {
+                parse_struct_type_str(v)?
+            } else if v.starts_with("map") {
+                // e.g. map<int,string>
+                let inner = extract_angle_brackets_inner(v, "map")?;
+                let (key_type_str, value_type_str) = split_comma_nesting_aware(inner);
+                DataType::List(Box::new(DataType::Struct(vec![
+                    Field::new(
+                        PlSmallStr::from_static("key"),
+                        parse_type_str(key_type_str)?,
+                    ),
+                    Field::new(
+                        PlSmallStr::from_static("value"),
+                        parse_type_str(value_type_str)?,
+                    ),
+                ])))
+            } else {
+                polars_bail!(
+                    ComputeError:
+                    "parse_type_str unknown type name: {}",
+                    v
+                )
+            }
+        },
+    };
+
+    Ok(dtype)
+}
+
+/// `array<inner> -> inner`
+fn extract_angle_brackets_inner<'a>(value: &'a str, name: &'static str) -> PolarsResult<&'a str> {
+    let i = value.find('<');
+    let j = value.rfind('>');
+
+    if i.is_none() || j.is_none() || i.unwrap().saturating_add(1) >= j.unwrap() {
+        polars_bail!(
+            ComputeError:
+            "type format did not match {}<...>: {}",
+            name, value
+        )
+    }
+
+    let i = i.unwrap();
+    let j = j.unwrap();
+
+    let inner = value[i + 1..j].trim();
+
+    Ok(inner)
+}
+
+/// `struct<default:decimal(38,18),promotional:struct<default:decimal(38,18)>,effective_list:struct<default:decimal(38,18)>>`
+fn parse_struct_type_str(value: &str) -> PolarsResult<DataType> {
+    let orig_value = value;
+    let mut value = extract_angle_brackets_inner(value, "struct")?;
+
+    let mut fields = vec![];
+
+    while !value.is_empty() {
+        let (field_str, new_value) = split_comma_nesting_aware(value);
+        value = new_value;
+
+        let (name, dtype_str) = field_str.split_once(':').ok_or_else(|| {
+            polars_err!(
+                ComputeError:
+                "type format did not match struct<name:type,..>: {}",
+                orig_value
+            )
+        })?;
+
+        let dtype = parse_type_str(dtype_str)?;
+
+        fields.push(Field::new(name.into(), dtype));
+    }
+
+    Ok(DataType::Struct(fields))
+}
+
+/// `default:decimal(38,18),promotional:struct<default:decimal(38,18)>` ->
+/// * 1: `default:decimal(38,18)`
+/// * 2: `struct<default:decimal(38,18)>`
+///
+/// If there are no splits, returns the full string and an empty string.
+fn split_comma_nesting_aware(value: &str) -> (&str, &str) {
+    let mut bracket_level = 0usize;
+    let mut angle_bracket_level = 0usize;
+
+    for (i, b) in value.as_bytes().iter().enumerate() {
+        match b {
+            b'(' => bracket_level += 1,
+            b')' => bracket_level = bracket_level.saturating_sub(1),
+            b'<' => angle_bracket_level += 1,
+            b'>' => angle_bracket_level = angle_bracket_level.saturating_sub(1),
+            b',' if bracket_level == 0 && angle_bracket_level == 0 => {
+                return (&value[..i], &value[1 + i..])
+            },
+            _ => {},
+        }
+    }
+
+    (value, &value[value.len()..])
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn test_parse_type_str_nested_struct() {
+        use super::{parse_type_str, DataType, Field};
+
+        let type_str = "struct<default:decimal(38,18),promotional:struct<default:decimal(38,18)>,effective_list:struct<default:decimal(38,18)>>";
+        let dtype = parse_type_str(type_str).unwrap();
+
+        use DataType::*;
+
+        assert_eq!(
+            dtype,
+            Struct(vec![
+                Field::new("default".into(), Decimal(Some(38), Some(18))),
+                Field::new(
+                    "promotional".into(),
+                    Struct(vec![Field::new(
+                        "default".into(),
+                        Decimal(Some(38), Some(18))
+                    )])
+                ),
+                Field::new(
+                    "effective_list".into(),
+                    Struct(vec![Field::new(
+                        "default".into(),
+                        Decimal(Some(38), Some(18))
+                    )])
+                )
+            ])
+        );
+    }
+
+    #[test]
+    fn test_parse_type_str_map() {
+        use super::{parse_type_str, DataType, Field};
+
+        let type_str = "map<array<int>,array<decimal(18,2)>>";
+        let dtype = parse_type_str(type_str).unwrap();
+
+        use DataType::*;
+
+        assert_eq!(
+            dtype,
+            List(Box::new(Struct(vec![
+                Field::new("key".into(), List(Box::new(Int32))),
+                Field::new("value".into(), List(Box::new(Decimal(Some(18), Some(2)))))
+            ])))
+        );
+    }
+}