Use ReadOnlyMemory<float> as the type for VECTOR.

Based on these comments: dotnet/runtime#115148 (comment).

Signed-off-by: Bradley Grainger <bgrainger@gmail.com>

Author: bgrainger

src/MySqlConnector/ColumnReaders/VectorColumnReader.cs

@@ -8,5 +8,5 @@ internal sealed class VectorColumnReader : ColumnReader
 	public static VectorColumnReader Instance { get; } = new();
 
 	public override object ReadValue(ReadOnlySpan<byte> data, ColumnDefinitionPayload columnDefinition) =>
-		MemoryMarshal.Cast<byte, float>(data).ToArray();
+		new ReadOnlyMemory<float>(MemoryMarshal.Cast<byte, float>(data).ToArray());
 }

src/MySqlConnector/Core/TypeMapper.cs

@@ -56,8 +56,8 @@ private TypeMapper()
 		AddColumnTypeMetadata(new("FLOAT", typeFloat, MySqlDbType.Float));
 
 		 // vector
-		var typeFloatArray = AddDbTypeMapping(new(typeof(float[]), [DbType.Object]));
-		AddColumnTypeMetadata(new("VECTOR", typeFloatArray, MySqlDbType.Vector, binary: true, simpleDataTypeName: "VECTOR", createFormat: "VECTOR({0})"));
+		var typeFloatReadOnlyMemory = AddDbTypeMapping(new(typeof(ReadOnlyMemory<float>), [DbType.Object]));
+		AddColumnTypeMetadata(new("VECTOR", typeFloatReadOnlyMemory, MySqlDbType.Vector, binary: true, simpleDataTypeName: "VECTOR", createFormat: "VECTOR({0})"));
 
 		// string
 		var typeFixedString = AddDbTypeMapping(new(typeof(string), [DbType.StringFixedLength, DbType.AnsiStringFixedLength], convert: Convert.ToString!));

tests/IntegrationTests/DataTypes.cs

@@ -1148,7 +1148,7 @@ private static object CreateGeometry(byte[] data)
 #if MYSQL_DATA
 	[InlineData("value", "datatypes_vector", MySqlDbType.Vector, 12, typeof(byte[]), "N", 0, 31)]
 #else
-	[InlineData("value", "datatypes_vector", MySqlDbType.Vector, 3, typeof(float[]), "N", 0, 31)]
+	[InlineData("value", "datatypes_vector", MySqlDbType.Vector, 3, typeof(ReadOnlyMemory<float>), "N", 0, 31)]
 #endif
 	[InlineData("Single", "datatypes_reals", MySqlDbType.Float, 12, typeof(float), "N", 0, 31)]
 	[InlineData("Double", "datatypes_reals", MySqlDbType.Double, 22, typeof(double), "N", 0, 31)]
@@ -1626,18 +1626,26 @@ public void QueryVector(string column, string[] expected)
 		DoQuery("vector", column, dataTypeName,
 			expected.Select(x =>
 #if !MYSQL_DATA
-				hasVectorType ? (object) GetFloatArray(x) : GetByteArray(x))
+				hasVectorType ? (GetFloatArray(x) is float[] a ? (object) new ReadOnlyMemory<float>(a) : null) : GetByteArray(x))
 #else
 				// Connector/NET returns the float array as a byte[]
 				GetByteArray(x))
 #endif
 			.ToArray(),
 #if !MYSQL_DATA
-			x => hasVectorType ? (float[]) x.GetValue(0) : (byte[]) x.GetValue(0),
+			x => hasVectorType ? (ReadOnlyMemory<float>) x.GetValue(0) : (byte[]) x.GetValue(0),
 #else
 			// NOTE: Connector/NET returns 'null' for NULL so simulate an exception for the tests
 			x => x.IsDBNull(0) ? throw new GetValueWhenNullException() : x.GetValue(0),
 #endif
+			assertEqual: (l, r) =>
+			{
+				if (l is ReadOnlyMemory<float> roml)
+					l = roml.ToArray();
+				if (r is ReadOnlyMemory<float> romr)
+					r = romr.ToArray();
+				Assert.Equal(l, r);
+			},
 			omitWhereTest: true);
 
 		static float[] GetFloatArray(string value) => value?.Split(',').Select(x => float.Parse(x, CultureInfo.InvariantCulture)).ToArray();

tests/IntegrationTests/QueryTests.cs

@@ -1735,7 +1735,7 @@ public void QueryVector(bool prepare)
 #if MYSQL_DATA
 		var result = MemoryMarshal.Cast<byte, float>((byte[]) value).ToArray();
 #else
-		var result = AppConfig.SupportedFeatures.HasFlag(ServerFeatures.VectorType) ? (float[]) value :
+		var result = AppConfig.SupportedFeatures.HasFlag(ServerFeatures.VectorType) ? (ReadOnlyMemory<float>) value :
 			MemoryMarshal.Cast<byte, float>((byte[]) value).ToArray();
 #endif
 		Assert.Equal(floatArray, result);