Support reading tables with type widening in default engine (#335)

Type widening allows changing the type of an existing column in a Delta table to a wider type. See https://github.com/delta-io/delta/blob/master/protocol_rfcs/type-widening.md This change improves the default engine to enable upcasting conversions on read that are required to read tables that have a type change applied: data files written before the widening type change will contain data stored using a narrower type that must be upcast to the wider type in the current table schema. Changes: - Allow conversions: - int8 -> int16 -> int32 -> int64 - float32 -> float64 - date -> timestamp without timezone - integers -> float64 - integers and decimals -> decimals, as long as the target precision and scale are sufficient to store all values without losing precision This doesn't cover casting inside nested struct/array/map, which doesn't seem to be properly supported yet. Testing: - Added tests reading a table with various type changes applied, generated using delta spark 4.0 preview. - Added unit tests for `can_upcast_to_decimal`, returning whether a given type can be upcast to a decimal.
delta-incubator · Sep 19, 2024 · 1a66fb9 · 1a66fb9
1 parent f6b8942
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diff --git a/kernel/src/engine/arrow_utils.rs b/kernel/src/engine/arrow_utils.rs
@@ -73,19 +73,54 @@ fn check_cast_compat(
     target_type: ArrowDataType,
     source_type: &ArrowDataType,
 ) -> DeltaResult<DataTypeCompat> {
+    use ArrowDataType::*;
+
     match (source_type, &target_type) {
         (source_type, target_type) if source_type == target_type => Ok(DataTypeCompat::Identical),
         (&ArrowDataType::Timestamp(_, _), &ArrowDataType::Timestamp(_, _)) => {
             // timestamps are able to be cast between each other
             Ok(DataTypeCompat::NeedsCast(target_type))
         }
+        // Allow up-casting to a larger type if it's safe and can't cause overflow or loss of precision.
+        (Int8, Int16 | Int32 | Int64 | Float64) => Ok(DataTypeCompat::NeedsCast(target_type)),
+        (Int16, Int32 | Int64 | Float64) => Ok(DataTypeCompat::NeedsCast(target_type)),
+        (Int32, Int64 | Float64) => Ok(DataTypeCompat::NeedsCast(target_type)),
+        (Float32, Float64) => Ok(DataTypeCompat::NeedsCast(target_type)),
+        (_, Decimal128(p, s)) if can_upcast_to_decimal(source_type, *p, *s) => {
+            Ok(DataTypeCompat::NeedsCast(target_type))
+        }
+        (Date32, Timestamp(_, None)) => Ok(DataTypeCompat::NeedsCast(target_type)),
         _ => Err(make_arrow_error(format!(
             "Incorrect datatype. Expected {}, got {}",
             target_type, source_type
         ))),
     }
 }
 
+// Returns whether the given source type can be safely cast to a decimal with the given precision and scale without
+// loss of information.
+fn can_upcast_to_decimal(
+    source_type: &ArrowDataType,
+    target_precision: u8,
+    target_scale: i8,
+) -> bool {
+    use ArrowDataType::*;
+
+    let (source_precision, source_scale) = match source_type {
+        Decimal128(p, s) => (*p, *s),
+        // Allow converting integers to a decimal that can hold all possible values.
+        Int8 => (3u8, 0i8),
+        Int16 => (5u8, 0i8),
+        Int32 => (10u8, 0i8),
+        Int64 => (20u8, 0i8),
+        _ => return false,
+    };
+
+    target_precision >= source_precision
+        && target_scale >= source_scale
+        && target_precision - source_precision >= (target_scale - source_scale) as u8
+}
+
 /// Ensure a kernel data type matches an arrow data type. This only ensures that the actual "type"
 /// is the same, but does so recursively into structs, and ensures lists and maps have the correct
 /// associated types as well. This returns an `Ok(DataTypeCompat)` if the types are compatible, and
@@ -1427,4 +1462,61 @@ mod tests {
         assert_eq!(mask_indices, expect_mask);
         assert_eq!(reorder_indices, expect_reorder);
     }
+
+    #[test]
+    fn accepts_safe_decimal_casts() {
+        use super::can_upcast_to_decimal;
+        use ArrowDataType::*;
+
+        assert!(can_upcast_to_decimal(&Decimal128(1, 0), 2u8, 0i8));
+        assert!(can_upcast_to_decimal(&Decimal128(1, 0), 2u8, 1i8));
+        assert!(can_upcast_to_decimal(&Decimal128(5, -2), 6u8, -2i8));
+        assert!(can_upcast_to_decimal(&Decimal128(5, -2), 6u8, -1i8));
+        assert!(can_upcast_to_decimal(&Decimal128(5, 1), 6u8, 1i8));
+        assert!(can_upcast_to_decimal(&Decimal128(5, 1), 6u8, 2i8));
+        assert!(can_upcast_to_decimal(
+            &Decimal128(10, 5),
+            arrow_schema::DECIMAL128_MAX_PRECISION,
+            arrow_schema::DECIMAL128_MAX_SCALE - 5
+        ));
+
+        assert!(can_upcast_to_decimal(&Int8, 3u8, 0i8));
+        assert!(can_upcast_to_decimal(&Int8, 4u8, 0i8));
+        assert!(can_upcast_to_decimal(&Int8, 4u8, 1i8));
+        assert!(can_upcast_to_decimal(&Int8, 7u8, 2i8));
+
+        assert!(can_upcast_to_decimal(&Int16, 5u8, 0i8));
+        assert!(can_upcast_to_decimal(&Int16, 6u8, 0i8));
+        assert!(can_upcast_to_decimal(&Int16, 6u8, 1i8));
+        assert!(can_upcast_to_decimal(&Int16, 9u8, 2i8));
+
+        assert!(can_upcast_to_decimal(&Int32, 10u8, 0i8));
+        assert!(can_upcast_to_decimal(&Int32, 11u8, 0i8));
+        assert!(can_upcast_to_decimal(&Int32, 11u8, 1i8));
+        assert!(can_upcast_to_decimal(&Int32, 14u8, 2i8));
+
+        assert!(can_upcast_to_decimal(&Int64, 20u8, 0i8));
+        assert!(can_upcast_to_decimal(&Int64, 21u8, 0i8));
+        assert!(can_upcast_to_decimal(&Int64, 21u8, 1i8));
+        assert!(can_upcast_to_decimal(&Int64, 24u8, 2i8));
+    }
+
+    #[test]
+    fn rejects_unsafe_decimal_casts() {
+        use super::can_upcast_to_decimal;
+        use ArrowDataType::*;
+
+        assert!(!can_upcast_to_decimal(&Decimal128(2, 0), 2u8, 1i8));
+        assert!(!can_upcast_to_decimal(&Decimal128(2, 0), 2u8, -1i8));
+        assert!(!can_upcast_to_decimal(&Decimal128(5, 2), 6u8, 4i8));
+
+        assert!(!can_upcast_to_decimal(&Int8, 2u8, 0i8));
+        assert!(!can_upcast_to_decimal(&Int8, 3u8, 1i8));
+        assert!(!can_upcast_to_decimal(&Int16, 4u8, 0i8));
+        assert!(!can_upcast_to_decimal(&Int16, 5u8, 1i8));
+        assert!(!can_upcast_to_decimal(&Int32, 9u8, 0i8));
+        assert!(!can_upcast_to_decimal(&Int32, 10u8, 1i8));
+        assert!(!can_upcast_to_decimal(&Int64, 19u8, 0i8));
+        assert!(!can_upcast_to_decimal(&Int64, 20u8, 1i8));
+    }
 }
diff --git a/kernel/src/features/mod.rs b/kernel/src/features/mod.rs
@@ -31,6 +31,11 @@ pub enum ReaderFeatures {
     #[strum(serialize = "timestampNtz")]
     #[serde(rename = "timestampNtz")]
     TimestampWithoutTimezone,
+    // Allow columns to change type
+    TypeWidening,
+    #[strum(serialize = "typeWidening-preview")]
+    #[serde(rename = "typeWidening-preview")]
+    TypeWideningPreview,
     /// version 2 of checkpointing
     V2Checkpoint,
 }
@@ -74,6 +79,11 @@ pub enum WriterFeatures {
     #[strum(serialize = "timestampNtz")]
     #[serde(rename = "timestampNtz")]
     TimestampWithoutTimezone,
+    // Allow columns to change type
+    TypeWidening,
+    #[strum(serialize = "typeWidening-preview")]
+    #[serde(rename = "typeWidening-preview")]
+    TypeWideningPreview,
     /// domain specific metadata
     DomainMetadata,
     /// version 2 of checkpointing
@@ -94,6 +104,8 @@ mod tests {
             (ReaderFeatures::ColumnMapping, "columnMapping"),
             (ReaderFeatures::DeletionVectors, "deletionVectors"),
             (ReaderFeatures::TimestampWithoutTimezone, "timestampNtz"),
+            (ReaderFeatures::TypeWidening, "typeWidening"),
+            (ReaderFeatures::TypeWideningPreview, "typeWidening-preview"),
             (ReaderFeatures::V2Checkpoint, "v2Checkpoint"),
         ];
 
@@ -126,6 +138,8 @@ mod tests {
             (WriterFeatures::DeletionVectors, "deletionVectors"),
             (WriterFeatures::RowTracking, "rowTracking"),
             (WriterFeatures::TimestampWithoutTimezone, "timestampNtz"),
+            (WriterFeatures::TypeWidening, "typeWidening"),
+            (WriterFeatures::TypeWideningPreview, "typeWidening-preview"),
             (WriterFeatures::DomainMetadata, "domainMetadata"),
             (WriterFeatures::V2Checkpoint, "v2Checkpoint"),
             (WriterFeatures::IcebergCompatV1, "icebergCompatV1"),

diff --git a/...ta/type-widening/.part-00000-61accb66-b740-416b-9f5b-f0fccaceb415-c000.snappy.parquet.crc b/...ta/type-widening/.part-00000-61accb66-b740-416b-9f5b-f0fccaceb415-c000.snappy.parquet.crc
diff --git a/...ta/type-widening/.part-00000-f6dbc649-d5bc-42b1-984c-4376799a50d9-c000.snappy.parquet.crc b/...ta/type-widening/.part-00000-f6dbc649-d5bc-42b1-984c-4376799a50d9-c000.snappy.parquet.crc
diff --git a/kernel/tests/data/type-widening/_delta_log/.00000000000000000000.json.crc b/kernel/tests/data/type-widening/_delta_log/.00000000000000000000.json.crc
diff --git a/kernel/tests/data/type-widening/_delta_log/.00000000000000000001.json.crc b/kernel/tests/data/type-widening/_delta_log/.00000000000000000001.json.crc
diff --git a/kernel/tests/data/type-widening/_delta_log/.00000000000000000002.json.crc b/kernel/tests/data/type-widening/_delta_log/.00000000000000000002.json.crc
diff --git a/kernel/tests/data/type-widening/_delta_log/00000000000000000000.json b/kernel/tests/data/type-widening/_delta_log/00000000000000000000.json
@@ -0,0 +1,4 @@
+{"commitInfo":{"timestamp":1726233749922,"operation":"WRITE","operationParameters":{"mode":"Append","partitionBy":"[]"},"isolationLevel":"Serializable","isBlindAppend":true,"operationMetrics":{"numFiles":"1","numOutputRows":"1","numOutputBytes":"3694"},"engineInfo":"Apache-Spark/3.5.2 Delta-Lake/3.3.0-SNAPSHOT","txnId":"329e27de-485a-4c93-af9c-bb0ea3452823"}}
+{"metaData":{"id":"e80ace91-dbef-4206-a821-e3f6c786f81c","format":{"provider":"parquet","options":{}},"schemaString":"{\"type\":\"struct\",\"fields\":[{\"name\":\"byte_long\",\"type\":\"byte\",\"nullable\":true,\"metadata\":{}},{\"name\":\"int_long\",\"type\":\"integer\",\"nullable\":true,\"metadata\":{}},{\"name\":\"float_double\",\"type\":\"float\",\"nullable\":true,\"metadata\":{}},{\"name\":\"byte_double\",\"type\":\"byte\",\"nullable\":true,\"metadata\":{}},{\"name\":\"short_double\",\"type\":\"short\",\"nullable\":true,\"metadata\":{}},{\"name\":\"int_double\",\"type\":\"integer\",\"nullable\":true,\"metadata\":{}},{\"name\":\"decimal_decimal_same_scale\",\"type\":\"decimal(10,2)\",\"nullable\":true,\"metadata\":{}},{\"name\":\"decimal_decimal_greater_scale\",\"type\":\"decimal(10,2)\",\"nullable\":true,\"metadata\":{}},{\"name\":\"byte_decimal\",\"type\":\"byte\",\"nullable\":true,\"metadata\":{}},{\"name\":\"short_decimal\",\"type\":\"short\",\"nullable\":true,\"metadata\":{}},{\"name\":\"int_decimal\",\"type\":\"integer\",\"nullable\":true,\"metadata\":{}},{\"name\":\"long_decimal\",\"type\":\"long\",\"nullable\":true,\"metadata\":{}},{\"name\":\"date_timestamp_ntz\",\"type\":\"date\",\"nullable\":true,\"metadata\":{}}]}","partitionColumns":[],"configuration":{},"createdTime":1726233743254}}
+{"protocol":{"minReaderVersion":1,"minWriterVersion":2}}
+{"add":{"path":"part-00000-f6dbc649-d5bc-42b1-984c-4376799a50d9-c000.snappy.parquet","partitionValues":{},"size":3694,"modificationTime":1726233749678,"dataChange":true,"stats":"{\"numRecords\":1,\"minValues\":{\"byte_long\":1,\"int_long\":2,\"float_double\":3.4,\"byte_double\":5,\"short_double\":6,\"int_double\":7,\"decimal_decimal_same_scale\":123.45,\"decimal_decimal_greater_scale\":67.89,\"byte_decimal\":1,\"short_decimal\":2,\"int_decimal\":3,\"long_decimal\":4,\"date_timestamp_ntz\":\"2024-09-09\"},\"maxValues\":{\"byte_long\":1,\"int_long\":2,\"float_double\":3.4,\"byte_double\":5,\"short_double\":6,\"int_double\":7,\"decimal_decimal_same_scale\":123.45,\"decimal_decimal_greater_scale\":67.89,\"byte_decimal\":1,\"short_decimal\":2,\"int_decimal\":3,\"long_decimal\":4,\"date_timestamp_ntz\":\"2024-09-09\"},\"nullCount\":{\"byte_long\":0,\"int_long\":0,\"float_double\":0,\"byte_double\":0,\"short_double\":0,\"int_double\":0,\"decimal_decimal_same_scale\":0,\"decimal_decimal_greater_scale\":0,\"byte_decimal\":0,\"short_decimal\":0,\"int_decimal\":0,\"long_decimal\":0,\"date_timestamp_ntz\":0}}"}}
diff --git a/kernel/tests/data/type-widening/_delta_log/00000000000000000001.json b/kernel/tests/data/type-widening/_delta_log/00000000000000000001.json
@@ -0,0 +1,3 @@
+{"commitInfo":{"timestamp":1726233754010,"operation":"SET TBLPROPERTIES","operationParameters":{"properties":"{\"delta.enableTypeWidening\":\"true\",\"delta.feature.timestampntz\":\"supported\"}"},"readVersion":0,"isolationLevel":"Serializable","isBlindAppend":true,"operationMetrics":{},"engineInfo":"Apache-Spark/3.5.2 Delta-Lake/3.3.0-SNAPSHOT","txnId":"d49bfb13-3563-4840-9641-4cb6d5685201"}}
+{"metaData":{"id":"e80ace91-dbef-4206-a821-e3f6c786f81c","format":{"provider":"parquet","options":{}},"schemaString":"{\"type\":\"struct\",\"fields\":[{\"name\":\"byte_long\",\"type\":\"byte\",\"nullable\":true,\"metadata\":{}},{\"name\":\"int_long\",\"type\":\"integer\",\"nullable\":true,\"metadata\":{}},{\"name\":\"float_double\",\"type\":\"float\",\"nullable\":true,\"metadata\":{}},{\"name\":\"byte_double\",\"type\":\"byte\",\"nullable\":true,\"metadata\":{}},{\"name\":\"short_double\",\"type\":\"short\",\"nullable\":true,\"metadata\":{}},{\"name\":\"int_double\",\"type\":\"integer\",\"nullable\":true,\"metadata\":{}},{\"name\":\"decimal_decimal_same_scale\",\"type\":\"decimal(10,2)\",\"nullable\":true,\"metadata\":{}},{\"name\":\"decimal_decimal_greater_scale\",\"type\":\"decimal(10,2)\",\"nullable\":true,\"metadata\":{}},{\"name\":\"byte_decimal\",\"type\":\"byte\",\"nullable\":true,\"metadata\":{}},{\"name\":\"short_decimal\",\"type\":\"short\",\"nullable\":true,\"metadata\":{}},{\"name\":\"int_decimal\",\"type\":\"integer\",\"nullable\":true,\"metadata\":{}},{\"name\":\"long_decimal\",\"type\":\"long\",\"nullable\":true,\"metadata\":{}},{\"name\":\"date_timestamp_ntz\",\"type\":\"date\",\"nullable\":true,\"metadata\":{}}]}","partitionColumns":[],"configuration":{"delta.enableTypeWidening":"true"},"createdTime":1726233743254}}
+{"protocol":{"minReaderVersion":3,"minWriterVersion":7,"readerFeatures":["timestampNtz","typeWidening-preview"],"writerFeatures":["timestampNtz","typeWidening-preview","appendOnly","invariants"]}}
diff --git a/kernel/tests/data/type-widening/_delta_log/00000000000000000002.json b/kernel/tests/data/type-widening/_delta_log/00000000000000000002.json
@@ -0,0 +1,3 @@
+{"commitInfo":{"timestamp":1726233756593,"operation":"WRITE","operationParameters":{"mode":"Append","partitionBy":"[]"},"readVersion":1,"isolationLevel":"Serializable","isBlindAppend":true,"operationMetrics":{"numFiles":"1","numOutputRows":"1","numOutputBytes":"4001"},"engineInfo":"Apache-Spark/3.5.2 Delta-Lake/3.3.0-SNAPSHOT","txnId":"18e0f057-e98c-4cd1-bd2a-56f106701dff"}}
+{"metaData":{"id":"e80ace91-dbef-4206-a821-e3f6c786f81c","format":{"provider":"parquet","options":{}},"schemaString":"{\"type\":\"struct\",\"fields\":[{\"name\":\"byte_long\",\"type\":\"long\",\"nullable\":true,\"metadata\":{\"delta.typeChanges\":[{\"toType\":\"long\",\"fromType\":\"byte\",\"tableVersion\":2}]}},{\"name\":\"int_long\",\"type\":\"long\",\"nullable\":true,\"metadata\":{\"delta.typeChanges\":[{\"toType\":\"long\",\"fromType\":\"integer\",\"tableVersion\":2}]}},{\"name\":\"float_double\",\"type\":\"double\",\"nullable\":true,\"metadata\":{\"delta.typeChanges\":[{\"toType\":\"double\",\"fromType\":\"float\",\"tableVersion\":2}]}},{\"name\":\"byte_double\",\"type\":\"double\",\"nullable\":true,\"metadata\":{\"delta.typeChanges\":[{\"toType\":\"double\",\"fromType\":\"byte\",\"tableVersion\":2}]}},{\"name\":\"short_double\",\"type\":\"double\",\"nullable\":true,\"metadata\":{\"delta.typeChanges\":[{\"toType\":\"double\",\"fromType\":\"short\",\"tableVersion\":2}]}},{\"name\":\"int_double\",\"type\":\"double\",\"nullable\":true,\"metadata\":{\"delta.typeChanges\":[{\"toType\":\"double\",\"fromType\":\"integer\",\"tableVersion\":2}]}},{\"name\":\"decimal_decimal_same_scale\",\"type\":\"decimal(20,2)\",\"nullable\":true,\"metadata\":{\"delta.typeChanges\":[{\"toType\":\"decimal(20,2)\",\"fromType\":\"decimal(10,2)\",\"tableVersion\":2}]}},{\"name\":\"decimal_decimal_greater_scale\",\"type\":\"decimal(20,5)\",\"nullable\":true,\"metadata\":{\"delta.typeChanges\":[{\"toType\":\"decimal(20,5)\",\"fromType\":\"decimal(10,2)\",\"tableVersion\":2}]}},{\"name\":\"byte_decimal\",\"type\":\"decimal(4,1)\",\"nullable\":true,\"metadata\":{\"delta.typeChanges\":[{\"toType\":\"decimal(4,1)\",\"fromType\":\"byte\",\"tableVersion\":2}]}},{\"name\":\"short_decimal\",\"type\":\"decimal(6,1)\",\"nullable\":true,\"metadata\":{\"delta.typeChanges\":[{\"toType\":\"decimal(6,1)\",\"fromType\":\"short\",\"tableVersion\":2}]}},{\"name\":\"int_decimal\",\"type\":\"decimal(11,1)\",\"nullable\":true,\"metadata\":{\"delta.typeChanges\":[{\"toType\":\"decimal(11,1)\",\"fromType\":\"integer\",\"tableVersion\":2}]}},{\"name\":\"long_decimal\",\"type\":\"decimal(21,1)\",\"nullable\":true,\"metadata\":{\"delta.typeChanges\":[{\"toType\":\"decimal(21,1)\",\"fromType\":\"long\",\"tableVersion\":2}]}},{\"name\":\"date_timestamp_ntz\",\"type\":\"timestamp_ntz\",\"nullable\":true,\"metadata\":{\"delta.typeChanges\":[{\"toType\":\"timestamp_ntz\",\"fromType\":\"date\",\"tableVersion\":2}]}}]}","partitionColumns":[],"configuration":{"delta.enableTypeWidening":"true"},"createdTime":1726233743254}}
+{"add":{"path":"part-00000-61accb66-b740-416b-9f5b-f0fccaceb415-c000.snappy.parquet","partitionValues":{},"size":4001,"modificationTime":1726233756528,"dataChange":true,"stats":"{\"numRecords\":1,\"minValues\":{\"byte_long\":9223372036854775807,\"int_long\":9223372036854775807,\"float_double\":1.234567890123,\"byte_double\":1.234567890123,\"short_double\":1.234567890123,\"int_double\":1.234567890123,\"decimal_decimal_same_scale\":12345678901234.56,\"decimal_decimal_greater_scale\":12345678901.23456,\"byte_decimal\":123.4,\"short_decimal\":12345.6,\"int_decimal\":1234567890.1,\"long_decimal\":123456789012345678.9,\"date_timestamp_ntz\":\"2024-09-09T12:34:56.123\"},\"maxValues\":{\"byte_long\":9223372036854775807,\"int_long\":9223372036854775807,\"float_double\":1.234567890123,\"byte_double\":1.234567890123,\"short_double\":1.234567890123,\"int_double\":1.234567890123,\"decimal_decimal_same_scale\":12345678901234.56,\"decimal_decimal_greater_scale\":12345678901.23456,\"byte_decimal\":123.4,\"short_decimal\":12345.6,\"int_decimal\":1234567890.1,\"long_decimal\":123456789012345678.9,\"date_timestamp_ntz\":\"2024-09-09T12:34:56.123\"},\"nullCount\":{\"byte_long\":0,\"int_long\":0,\"float_double\":0,\"byte_double\":0,\"short_double\":0,\"int_double\":0,\"decimal_decimal_same_scale\":0,\"decimal_decimal_greater_scale\":0,\"byte_decimal\":0,\"short_decimal\":0,\"int_decimal\":0,\"long_decimal\":0,\"date_timestamp_ntz\":0}}","defaultRowCommitVersion":2}}
diff --git a/...ts/data/type-widening/part-00000-61accb66-b740-416b-9f5b-f0fccaceb415-c000.snappy.parquet b/...ts/data/type-widening/part-00000-61accb66-b740-416b-9f5b-f0fccaceb415-c000.snappy.parquet
diff --git a/...ts/data/type-widening/part-00000-f6dbc649-d5bc-42b1-984c-4376799a50d9-c000.snappy.parquet b/...ts/data/type-widening/part-00000-f6dbc649-d5bc-42b1-984c-4376799a50d9-c000.snappy.parquet
diff --git a/kernel/tests/read.rs b/kernel/tests/read.rs
@@ -1040,3 +1040,47 @@ fn timestamp_ntz() -> Result<(), Box<dyn std::error::Error>> {
     )?;
     Ok(())
 }
+
+#[test]
+fn type_widening_basic() -> Result<(), Box<dyn std::error::Error>> {
+    let expected = vec![
+        "+---------------------+---------------------+--------------------+----------------+----------------+----------------+----------------------------+",
+        "| byte_long           | int_long            | float_double       | byte_double    | short_double   | int_double     | date_timestamp_ntz         |",
+        "+---------------------+---------------------+--------------------+----------------+----------------+----------------+----------------------------+",
+        "| 1                   | 2                   | 3.4000000953674316 | 5.0            | 6.0            | 7.0            | 2024-09-09T00:00:00        |",
+        "| 9223372036854775807 | 9223372036854775807 | 1.234567890123     | 1.234567890123 | 1.234567890123 | 1.234567890123 | 2024-09-09T12:34:56.123456 |",
+        "+---------------------+---------------------+--------------------+----------------+----------------+----------------+----------------------------+",
+   ];
+    let select_cols: Option<&[&str]> = Some(&[
+        "byte_long",
+        "int_long",
+        "float_double",
+        "byte_double",
+        "short_double",
+        "int_double",
+        "date_timestamp_ntz",
+    ]);
+
+    read_table_data_str("./tests/data/type-widening/", select_cols, None, expected)
+}
+
+#[test]
+fn type_widening_decimal() -> Result<(), Box<dyn std::error::Error>> {
+    let expected = vec![
+        "+----------------------------+-------------------------------+--------------+---------------+--------------+----------------------+",
+        "| decimal_decimal_same_scale | decimal_decimal_greater_scale | byte_decimal | short_decimal | int_decimal  | long_decimal         |",
+        "+----------------------------+-------------------------------+--------------+---------------+--------------+----------------------+",
+        "| 123.45                     | 67.89000                      | 1.0          | 2.0           | 3.0          | 4.0                  |",
+        "| 12345678901234.56          | 12345678901.23456             | 123.4        | 12345.6       | 1234567890.1 | 123456789012345678.9 |",
+        "+----------------------------+-------------------------------+--------------+---------------+--------------+----------------------+",
+    ];
+    let select_cols: Option<&[&str]> = Some(&[
+        "decimal_decimal_same_scale",
+        "decimal_decimal_greater_scale",
+        "byte_decimal",
+        "short_decimal",
+        "int_decimal",
+        "long_decimal",
+    ]);
+    read_table_data_str("./tests/data/type-widening/", select_cols, None, expected)
+}