How do we stream data from MySQL? Traditionally, developers have thought that they can simply use their API's cursor-equivalent object (e.g. resultset) and move through the results.
Unfortunately, this does not do streaming in most cases. Normally most client libraries (which call mysql_store_result) will read the entire result into memory, and you're just going through an already-in-memory data set. This will fail if it doesn't fit in memory.
Enter mysql_use_result - if your library can use this instead of mysql_store_result, you can then skip through the records without needing to keep them all in ram at once.
However, there is some bad news - while going through a result set in mysql_use_result, you can't do any OTHER queries on the connection. An attempt to do so generally violates MySQL's protocol and fails. So if you need to do other …