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How to Fix acedao.dll Memory Leaks Using DAO Seek in C#

Huda Qurayshi Sep 30, 2026 869 views

Question details

The user needs to resolve a memory leak in acedao.dll caused by repeated DAO Seek operations in a C# application.

How to Fix acedao.dll Memory Leaks When Using DAO Seek

Product: Microsoft Access 365
Device & OS: not provided
Scenario: Executing repeated Seek operations on a table-type recordset using Microsoft Access DAO in a C# application.
Observed behavior: The application leaks memory through acedao.dll, leading to excessive memory consumption.

Before you start

Ensure you have access to the C# application source code and that your development environment is set up to compile and debug Microsoft.Office.Interop.Access.Dao references.

Solution 1Recommended

Explicitly Dispose Unmanaged DAO Objects

Properly close and release unmanaged COM objects to prevent memory leaks during repetitive tasks.

DAO objects are unmanaged resources. When accessed via C#, the .NET Garbage Collector does not automatically release the underlying COM objects immediately. This leads to apparent memory leaks during repetitive tasks like Seek operations.

Identify DAO objects

Locate all database and recordset objects in your C# code that utilize DAO Seek.

Implement using statements

Wrap your DAO operations within 'using' statements or 'try-finally' blocks to ensure resources are predictably managed.

Close connections manually

Explicitly call the 'Close()' method on recordsets and databases as soon as they are no longer needed in the execution flow.

Release COM objects

Use 'System.Runtime.InteropServices.Marshal.ReleaseComObject()' to safely decrement the reference count of the unmanaged DAO COM objects.

Explicitly Dispose Unmanaged DAO Objects

VB6 to C# Migration: If your application was converted from VB6, automatic object disposal might be missing. Manually adding these cleanup blocks is critical for C#.

Solution 2

Verify Process and Provider Bitness

Ensure the application architecture matches the Access database engine version to rule out environment conflicts.

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Frequently Asked Questions

Why is Seek used instead of standard ADO.NET queries?

Seek is a DAO-specific operation that bypasses the SQL parser and query planner, making it significantly faster for certain index-based database lookups. However, it is not available through standard ADO.NET and requires careful manual memory management.

Can I use OLE DB or ODBC to avoid this memory leak?

Yes, OLE DB or ODBC are excellent alternatives for normal database access and standard queries in .NET. However, if your application relies specifically on the performance benefits of DAO Seek, you must explicitly manage COM object disposal instead of switching technologies.

Why does the leak only appear in C# and not in the original VB6 application?

VB6 utilizes deterministic reference counting, immediately releasing COM objects when they go out of scope. C# uses a non-deterministic garbage collector, meaning unmanaged COM objects like acedao.dll can linger in memory unless they are explicitly released by the developer.

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