fix: add decimal expr parsing

crates/core/src/delta_datafusion/expr.rs

@@ -502,6 +502,10 @@ impl fmt::Display for ScalarValueFormat<'_> {
             ScalarValue::UInt16(e) => format_option!(f, e)?,
             ScalarValue::UInt32(e) => format_option!(f, e)?,
             ScalarValue::UInt64(e) => format_option!(f, e)?,
+            ScalarValue::Decimal128(e, precision, scale) => match e {
+                Some(e) => write!(f, "'{e}'::decimal({precision}, {scale})",)?,
+                None => write!(f, "NULL")?,
+            },
             ScalarValue::Date32(e) => match e {
                 Some(e) => write!(
                     f,
@@ -657,6 +661,11 @@ mod test {
                 DataType::Primitive(PrimitiveType::Binary),
                 true,
             ),
+            StructField::new(
+                "_decimal".to_string(),
+                DataType::Primitive(PrimitiveType::Decimal(2, 2)),
+                true,
+            ),
             StructField::new(
                 "_struct".to_string(),
                 DataType::Struct(Box::new(StructType::new(vec![
@@ -887,6 +896,18 @@ mod test {
                     )
                 )),
             },
+            ParseTest {
+                expr: col("_decimal").eq(lit(ScalarValue::Decimal128(Some(1),2,2))),
+                expected: "_decimal = '1'::decimal(2, 2)".to_string(),
+                override_expected_expr: Some(col("_decimal").eq(
+                    Expr::Cast(
+                        Cast {
+                            expr: Box::from(lit("1")),
+                            data_type: arrow_schema::DataType::Decimal128(2, 2)
+                        }
+                    )
+                )),
+            },
         ];
 
         let session: SessionContext = DeltaSessionContext::default().into();
@@ -908,11 +929,6 @@ mod test {
         }
 
         let unsupported_types = vec![
-            /* TODO: Determine proper way to display decimal values in an sql expression*/
-            simple!(
-                col("money").gt(lit(ScalarValue::Decimal128(Some(100), 12, 2))),
-                "money > 0.1".to_string()
-            ),
             simple!(
                 col("_timestamp").gt(lit(ScalarValue::TimestampMillisecond(Some(100), None))),
                 "".to_string()

python/tests/test_merge.py

@@ -1,6 +1,7 @@
 import datetime
 import os
 import pathlib
+from decimal import Decimal
 
 import pyarrow as pa
 import pyarrow.parquet as pq
@@ -1149,3 +1150,44 @@ def test_merge_when_wrong_but_castable_type_passed_while_merge(
         tmp_path / dt.get_add_actions().column(0)[0].as_py()
     ).schema
     assert table_schema.field("price").type == sample_table["price"].type
+
+
+def test_merge_on_decimal_3033(tmp_path):
+    data = {
+        "timestamp": [datetime.datetime(2024, 3, 20, 12, 30, 0)],
+        "altitude": [Decimal("150.5")],
+    }
+
+    table = pa.Table.from_pydict(data)
+
+    schema = pa.schema(
+        [
+            ("timestamp", pa.timestamp("us")),
+            ("altitude", pa.decimal128(6, 1)),
+        ]
+    )
+
+    dt = DeltaTable.create(tmp_path, schema=schema)
+
+    write_deltalake(dt, table, mode="append")
+
+    dt.merge(
+        source=table,
+        predicate="target.timestamp = source.timestamp",
+        source_alias="source",
+        target_alias="target",
+    ).when_matched_update_all().when_not_matched_insert_all().execute()
+
+    dt.merge(
+        source=table,
+        predicate="target.timestamp = source.timestamp AND target.altitude = source.altitude",
+        source_alias="source",
+        target_alias="target",
+    ).when_matched_update_all().when_not_matched_insert_all().execute()
+
+    string_predicate = dt.history(1)[0]["operationParameters"]["predicate"]
+
+    assert (
+        string_predicate
+        == "timestamp BETWEEN arrow_cast('2024-03-20T12:30:00.000000', 'Timestamp(Microsecond, None)') AND arrow_cast('2024-03-20T12:30:00.000000', 'Timestamp(Microsecond, None)') AND altitude BETWEEN '1505'::decimal(4, 1) AND '1505'::decimal(4, 1)"
+    )