boolean truncate(int newIndexCnt) {
		if (newIndexCnt >= nextIndex) {
			return false;
		}
		nextIndex = newIndexCnt;
		
		// Remove free indexes which have been lost
		int cnt = freeIndexStack.size();
		for (int i = cnt-1; i >= 0; --i) {
			int freeIndex = freeIndexStack.get(i).intValue();
			if (freeIndex >= newIndexCnt) {
				freeIndexStack.remove(i);
			}
		}
		return true;
	}
Truncate this buffer file.  This method has no affect if the specified 
newBufferCnt is greater than the current buffer count.
@param newIndexCnt new index count
@return true if successful, false if newIndexCnt is larger than current 
index count.
Ghidra/Framework/DB/src/main/java/db/buffers/IndexProvider.java