Following MySQL's BLOB Field Design, Can Paimon Also Support Streaming Write Capabilities for BLOB Fields?MySQL Large Object Storage1. BINARY vs BLOB
MySQL supports two binary data types: BINARY and BLOB. - BINARY is a fixed-length binary string type, similar to CHAR, but it stores raw bytes instead of characters. It is suitable for small, fixed-size binary data. - BLOB (Binary Large Object) is a variable-length type designed to store large amounts of binary data such as images, audio, video, documents, and other file types. Note: Currently, Apache Paimon only supports the Binary type and does not have a dedicated BLOB type with streaming I/O capabilities. 2. Operation InterfacesInput Streams (Writing Data) When inserting or updating BLOB data, MySQL provides several methods through the JDBC API: - setBinaryStream(int index, InputStream x, int length) Writes binary data from an input stream into a BLOB field. This method is recommended for streaming large files, as it avoids loading the entire data into memory. - setBlob(int index, InputStream inputStream) (available since JDBC 4.0) A more modern approach that writes BLOB data using an input stream without requiring the length to be specified upfront. This simplifies handling dynamically sized data. - setBytes(int index, byte[] bytes) Directly writes a byte array to the BLOB field. This is appropriate only for small files (e.g., less than 1MB), as it can lead to high memory consumption and potential OutOfMemoryError (OOM) for larger data. Output Streams (Reading Data) When retrieving BLOB data from a result set, streaming access is supported to prevent memory issues: - getBinaryStream(String columnName) Reads the BLOB value as an input stream, enabling chunked reading of large files. This is the recommended way to handle large binary objects and avoid OOM. - getBinaryStream(int index) Similar to the above method, but accesses the column by its numeric index instead of name. It is useful when the column order is known and stable. Large Object Handling (Blob) In addition to direct stream access, MySQL allows working with the java.sql.Blob interface for more advanced operations: - ResultSet.getBlob(String columnName) Retrieves a java.sql.Blob object from the result set, which provides additional methods for manipulation. - Blob.getBinaryStream() Returns an input stream from the Blob object, typically used in conjunction with ResultSet.getBlob() to enable lazy or on-demand reading. - Blob.length() Returns the size (in bytes) of the BLOB data. This is useful for allocating buffers, determining file size, or managing partial reads. Byte Array Access - ResultSet.getBytes(String columnName) Reads the entire BLOB content directly into a byte array. While convenient for small data, this method should be avoided for large files, as it may cause OutOfMemoryError due to excessive memory usage. ------------------------------ This completes the description of MySQL’s BLOB handling mechanisms, focusing solely on factual presentation without additional analysis or recommendations.
