Enhance temporary table name generation with random suffix for uniqueness (#80)

* Enhance temporary table name generation with random suffix for uniqueness

* Skip tests for Oracle provider due to direct path operation restriction

* Refactor temporary table name generation for Oracle to use an 8-character random suffix for uniqueness and use Shared random generator

Author: PhenX

src/PhenX.EntityFrameworkCore.BulkInsert.MySql/MySqlBulkInsertProvider.cs

@@ -19,7 +19,7 @@ internal class MySqlBulkInsertProvider(ILogger<MySqlBulkInsertProvider> logger)
     protected override string AddTableCopyBulkInsertId => $"ALTER TABLE {{0}} ADD {BulkInsertId} INT AUTO_INCREMENT PRIMARY KEY;";
 
     /// <inheritdoc />
-    protected override string GetTempTableName(string tableName) => $"#_temp_bulk_insert_{tableName}";
+    protected override string GetTempTableName(string tableName) => $"#_temp_bulk_insert_{tableName}_{Helpers.RandomString(6)}";
 
     /// <inheritdoc />
     protected override MySqlBulkInsertOptions CreateDefaultOptions() => new()

src/PhenX.EntityFrameworkCore.BulkInsert.Oracle/OracleBulkInsertProvider.cs

@@ -21,10 +21,10 @@ internal class OracleBulkInsertProvider(ILogger<OracleBulkInsertProvider>? logge
 
     /// <inheritdoc />
     /// <summary>
-    /// The temporary table name is generated with a GUID to ensure uniqueness, but limited to less than 30 characters,
-    /// because Oracle prior 12.2 has a limit of 30 characters for identifiers.
+    /// The temporary table name is generated with a random 8-character suffix to ensure uniqueness, and is limited to less than 30 characters,
+    /// because Oracle prior to 12.2 has a limit of 30 characters for identifiers.
     /// </summary>
-    protected override string GetTempTableName(string tableName) => $"#temp_bulk_insert_{Guid.NewGuid().ToString("N")[..8]}";
+    protected override string GetTempTableName(string tableName) => $"#temp_bulk_insert_{Helpers.RandomString(8)}";
 
     protected override OracleBulkInsertOptions CreateDefaultOptions() => new()
     {

src/PhenX.EntityFrameworkCore.BulkInsert.SqlServer/SqlServerBulkInsertProvider.cs

@@ -17,7 +17,7 @@ internal class SqlServerBulkInsertProvider(ILogger<SqlServerBulkInsertProvider>?
     protected override string AddTableCopyBulkInsertId => $"ALTER TABLE {{0}} ADD {BulkInsertId} INT IDENTITY PRIMARY KEY;";
 
     /// <inheritdoc />
-    protected override string GetTempTableName(string tableName) => $"#_temp_bulk_insert_{tableName}";
+    protected override string GetTempTableName(string tableName) => $"#_temp_bulk_insert_{tableName}_{Helpers.RandomString(6)}";
 
     protected override SqlServerBulkInsertOptions CreateDefaultOptions() => new()
     {

src/PhenX.EntityFrameworkCore.BulkInsert.Sqlite/SqliteBulkInsertProvider.cs

@@ -24,7 +24,7 @@ internal class SqliteBulkInsertProvider(ILogger<SqliteBulkInsertProvider>? logge
     protected override string AddTableCopyBulkInsertId => "--"; // No need to add an ID column in SQLite
 
     /// <inheritdoc />
-    protected override string GetTempTableName(string tableName) => $"_temp_bulk_insert_{Guid.NewGuid():N}";
+    protected override string GetTempTableName(string tableName) => $"_temp_bulk_insert_{Helpers.RandomString(6)}";
 
     /// <inheritdoc />
     protected override BulkInsertOptions CreateDefaultOptions() => new()

src/PhenX.EntityFrameworkCore.BulkInsert/BulkInsertProviderBase.cs

@@ -19,7 +19,7 @@ internal abstract class BulkInsertProviderBase<TDialect, TOptions>(ILogger? logg
 
     protected abstract string AddTableCopyBulkInsertId { get; }
 
-    protected virtual string GetTempTableName(string tableName) => $"_temp_bulk_insert_{tableName}";
+    protected virtual string GetTempTableName(string tableName) => $"_temp_bulk_insert_{tableName}_{Helpers.RandomString(6)}";
 
     protected override async IAsyncEnumerable<T> BulkInsertReturnEntities<T>(
         bool sync,
@@ -124,6 +124,7 @@ protected override async Task BulkInsert<T>(
             await connection.Close(sync, ctk);
         }
     }
+
     private async Task<string> PerformBulkInsertAsync<T>(
         bool sync,
         DbContext context,

src/PhenX.EntityFrameworkCore.BulkInsert/Helpers.cs

@@ -27,4 +27,21 @@ public static StringBuilder AppendColumns(this StringBuilder sb, IReadOnlyList<C
     {
         return sb.AppendJoin(", ", columns.Select(c => c.QuotedColumName));
     }
+
+    /// <summary>
+    /// Generates a random alphanumeric string of the specified length.
+    /// </summary>
+    public static string RandomString(int length)
+    {
+        const string chars = "abcdefghijklmnopqrstuvwxyz0123456789";
+
+        var sb = new StringBuilder(length);
+
+        for (var i = 0; i < length; i++)
+        {
+            sb.Append(chars[Random.Shared.Next(chars.Length)]);
+        }
+
+        return sb.ToString();
+    }
 }

tests/PhenX.EntityFrameworkCore.BulkInsert.Tests/Tests/Basic/BasicTestsBase.cs

@@ -235,6 +235,34 @@ public async Task InsertEntities_WithOpenTransaction_RollsBackOnFailure(InsertSt
         Assert.Empty(insertedEntities);
     }
 
+    [SkippableTheory]
+    [CombinatorialData]
+    public async Task InsertEntities_WithOpenTransaction_MultipleInserts(InsertStrategy strategy)
+    {
+        // Oracle: ORA-39822: A new direct path operation is not allowed in the current transaction.
+        Skip.If(_context.IsProvider(ProviderType.Oracle));
+
+        // Arrange
+        var entities = new List<TestEntity>
+        {
+            new TestEntity { TestRun = _run, Name = $"{_run}_EntityWithTx1" },
+            new TestEntity { TestRun = _run, Name = $"{_run}_EntityWithTx2" },
+            new TestEntity { TestRun = _run, Name = $"{_run}_EntityWithTx3" },
+            new TestEntity { TestRun = _run, Name = $"{_run}_EntityWithTx4" },
+        };
+
+        // Act
+        await using var transaction = await _context.Database.BeginTransactionAsync();
+
+        var batches = entities.Chunk(2);
+        foreach (var batch in batches)
+        {
+            await _context.InsertWithStrategyAsync(strategy, batch.ToList());
+        }
+
+        await transaction.CommitAsync();
+    }
+
     [SkippableFact]
     public async Task ThrowsWhenUsingWrongConfigurationType()
     {