Method delete_blob

src/jrd/blb.cpp:2180–2265

void blb::delete_blob(thread_db* tdbb, ULONG prior_page)
{
/**************************************
 *
 *      d e l e t e _ b l o b
 *
 **************************************
 *
 * Functional description
 *      Delete all disk storage associated with blob.  This can be used
 *      to either abort a temporary blob or get rid of an unwanted and
 *      unloved permanent blob.  The routine deletes only blob page --
 *      somebody else will have to worry about the blob root.
 *
 **************************************/
	SET_TDBB(tdbb);
	Database* const dbb = tdbb->getDatabase();
	CHECK_DBB(dbb);

	const USHORT pageSpaceID = blb_pg_space_id;

	if (dbb->readOnly())
	{
		const USHORT tempSpaceID = dbb->dbb_page_manager.getTempPageSpaceID(tdbb);

		if (pageSpaceID != tempSpaceID)
		{
			ERR_post(Arg::Gds(isc_read_only_database));
		}
	}

	// Level 0 blobs don't need cleanup

	if (blb_level == 0)
		return;

	const PageNumber prior(pageSpaceID, prior_page);

	// Level 1 blobs just need the root page level released

	vcl::iterator ptr = blb_pages->begin();
	const vcl::iterator end = blb_pages->end();

	if (blb_level == 1)
	{
		for (; ptr < end; ++ptr)
		{
			if (*ptr) {
				PAG_release_page(tdbb, PageNumber(pageSpaceID, *ptr), prior);
			}
		}
		return;
	}

	// Level 2 blobs need a little more work to keep the page precedence
	// in order.  The basic problem is that the pointer page has to be
	// released before the data pages that it points to.  Sigh.