zzzzming95 opened a new issue, #138: URL: https://github.com/apache/arrow-java/issues/138
### Describe the usage question you have. Please include as many useful details as possible. [java] Is there a way to get the length of the data from bytes at a small system cost? Like the arrow doc example, https://arrow.apache.org/docs/java/ipc.html#writing-and-reading-streaming-format We generate the arrow data to bytes[] and transfer it. ``` ByteArrayOutputStream out = new ByteArrayOutputStream(); // create VectorSchemaRoot List<Field> fields = Arrays.asList(encodedVector.getField()); List<FieldVector> vectors = Arrays.asList(encodedVector); try (VectorSchemaRoot root = new VectorSchemaRoot(fields, vectors)) { // write data ArrowStreamWriter writer = new ArrowStreamWriter(root, provider, Channels.newChannel(out)); writer.start(); writer.writeBatch(); writer.end(); } // gen arrow data as bytep[] out.toByteArray() ``` I want to get the data length with a small system load(cpu mem). Now i using this way to get data lengeh: ``` ByteArrayInputStream input = new ByteArrayInputStream(out.toByteArray()); ReadChannel readChannel = new ReadChannel(Channels.newChannel(input)); MessageMetadataResult messageMeta = MessageSerializer.readMessage(readChannel); RecordBatch recordBatch = (RecordBatch) messageMeta.getMessage().header(new RecordBatch()); input.close(); readChannel.close(); // get data length recordBatch.length() ``` Is there documentation to guide me on what to do? thanks~ ### Component(s) Java -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: issues-unsubscr...@arrow.apache.org.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
