private FieldKeyNode getFieldKeyNode(int bufferId) throws IOException {
		if (schema.useFixedKeyNodes()) {
			return nodeMgr.getFixedKeyNode(bufferId);
		}
		return nodeMgr.getVarKeyNode(bufferId);
	}
Get node identified by buffer - must be released by caller (requires DBHandle lock)
@param bufferId buffer ID
@return buffer node
@throws IOException if IO error occurs
Ghidra/Framework/DB/src/main/java/db/Table.java