(PHP 5, PECL OCI8 >= 1.1.0)
OCI-Lob->flush — Flushes/writes buffer of the LOB to the server
OCI-Lob->flush() actually writes data to the server.
By default, resources are not freed, but using flag OCI_LOB_BUFFER_FREE you can do it explicitly. Be sure you know what you're doing - next read/write operation to the same part of LOB will involve a round-trip to the server and initialize new buffer resources. It is recommended to use OCI_LOB_BUFFER_FREE flag only when you are not going to work with the LOB anymore.
成功时返回 TRUE， 或者在失败时返回 FALSE.
Returns FALSE if buffering was not enabled or an error occurred.