Method setupBitmaps

src/jrd/recsrc/IndexTableScan.cpp:736–762

}

bool IndexTableScan::setupBitmaps(thread_db* tdbb, Impure* impure) const
{
	// Start a bitmap which tells us we have already visited
	// this record; this is to handle the case where there is more
	// than one leaf node reference to the same record number; the
	// bitmap allows us to filter out the multiple references.
	RecordBitmap::reset(impure->irsb_nav_records_visited);
	impure->irsb_flags |= irsb_mustread;

	// the first time we open the stream, compute a bitmap
	// for the inversion tree -- this may cause problems for
	// read-committed transactions since they will get one
	// view of the database when the stream is opened
	if (m_inversion)
	{
		if (!m_condition || !m_condition->execute(tdbb, tdbb->getRequest()))
		{
			impure->irsb_flags &= ~irsb_mustread;
			// There is no need to reset or release the bitmap, it is
			// done in EVL_bitmap()
			impure->irsb_nav_bitmap = EVL_bitmap(tdbb, m_inversion, NULL);
			return (*impure->irsb_nav_bitmap != NULL);
		}
	}

	return true;
}