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Description

The ORA-29258 error in Oracle Database indicates that the buffer allocated for an input or output operation is insufficient to hold the data being processed. This typically occurs during network communication or file operations when the buffer size is smaller than the actual data size.

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Error Message

ORA-29258: buffer too small

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Known Causes

3 known causes

⚠️

Insufficient Buffer Size

The buffer allocated for receiving data from a network connection or reading from a file is smaller than the data being received or read. 💻

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Incorrect Buffer Allocation

The buffer was not allocated with sufficient memory to accommodate the expected data size, leading to overflow. ⚙

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Data Size Mismatch

The expected data size was miscalculated or not properly considered when allocating the buffer. 🌐

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Solutions

3 solutions available

1. Increase UTL_TCP Buffer Size medium

Adjust the UTL_TCP maximum buffer size parameter for the specific connection.

1

Identify the UTL_TCP connection or the procedure that is failing. The ORA-29258 error typically occurs when using packages like UTL_TCP or UTL_HTTP for network operations where the buffer allocated for data transfer is insufficient.

2

Modify the `utl_tcp.open_connection` or related UTL_TCP calls to explicitly specify a larger buffer size. The `buffer_size` parameter controls the maximum amount of data that can be sent or received in a single operation.

DECLARE
  l_connection utl_tcp.connection;
  l_buffer_size NUMBER := 32767; -- Example: Increase to 32KB. Adjust as needed.
BEGIN
  l_connection := utl_tcp.open_connection(
    remote_host => 'your_remote_host',
    remote_port => 1234,
    charset     => 'US7ASCII',
    timeout     => 60,
    buffer_size => l_buffer_size  -- Specify a larger buffer size here
  );
  -- ... rest of your UTL_TCP operations ...
  utl_tcp.close_connection(l_connection);
END;
/

3

If the error occurs within a stored procedure or package, locate the `UTL_TCP.OPEN_CONNECTION` call within that code and apply the `buffer_size` parameter modification.

2. Tune Network Buffer Parameters (Advanced) advanced

Investigate and adjust Oracle Net Services buffer parameters if the issue is systemic.

1

This is a more advanced solution and should be approached with caution. The ORA-29258 error can sometimes be an indicator of underlying network buffer limitations. Examine Oracle Net Services configuration parameters, particularly those related to TCP/IP buffering.

2

On the Oracle database server (and potentially the client machine), check the operating system's TCP buffer settings. These are OS-level parameters that Oracle leverages. For example, on Linux, you might look at `net.core.rmem_max`, `net.core.wmem_max`, `net.ipv4.tcp_rmem`, and `net.ipv4.tcp_wmem`.

sysctl -a | grep net.ipv4.tcp

3

If OS-level tuning is necessary, consult your OS administrator for guidance. Changes to these parameters can have wide-ranging effects on network performance. Examples of potential adjustments (use with extreme caution and testing):

# Example for Linux (not recommended to apply without thorough testing and understanding)
sysctl -w net.core.rmem_max=16777216
sysctl -w net.core.wmem_max=16777216
sysctl -w net.ipv4.tcp_rmem="4096 87380 16777216"
sysctl -w net.ipv4.tcp_wmem="4096 65536 16777216"

4

Consider Oracle Net Services parameters like `TCP.BUFFER` in `sqlnet.ora`. While `UTL_TCP` often uses OS defaults or its own explicit buffer, in some scenarios, global Net parameters might indirectly influence behavior. However, directly increasing `UTL_TCP`'s buffer is usually the primary approach.

3. Break Down Large Data Transfers easy

Process data in smaller chunks to avoid exceeding buffer limits.

1

If you are transferring very large amounts of data in a single `UTL_TCP` or `UTL_HTTP` operation, the buffer might be too small to hold the entire payload. Redesign your logic to send or receive data in smaller, manageable chunks.

2

Instead of a single `UTL_TCP.write` or `UTL_TCP.read` for the entire dataset, implement a loop that processes data in batches. For example, fetch rows from a table in chunks and then write each chunk using `UTL_TCP`.

DECLARE
  l_connection utl_tcp.connection;
  CURSOR c_data IS SELECT /*+ ROWID(t) */ * FROM large_data_table t WHERE ROWNUM <= 1000; -- Fetch in batches
  l_record large_data_table%ROWTYPE;
  l_buffer VARCHAR2(32767);
BEGIN
  l_connection := utl_tcp.open_connection(...);

  OPEN c_data;
  LOOP
    FETCH c_data INTO l_record;
    EXIT WHEN c_data%NOTFOUND;

    -- Construct your data string/buffer for the current batch
    l_buffer := 'Processing: ' || l_record.column1 || ', ' || l_record.column2;

    -- Write the buffer for the current batch
    utl_tcp.write_line(l_connection, l_buffer);

  END LOOP;
  CLOSE c_data;

  utl_tcp.close_connection(l_connection);
END;
/

3

Ensure that your application logic correctly handles the fragmented data on the receiving end, reassembling the pieces as needed.

Oracle ORA-29258: Buffer Too Small