static Datum create_vertex()

in src/backend/executor/cypher_create.c [447:604]

• 89 lines of code
• 10 McCabe index (conditional complexity)

static Datum create_vertex(cypher_create_custom_scan_state *css,
                           cypher_target_node *node, ListCell *next, List *list)
{
    bool isNull;
    Datum id;
    EState *estate = css->css.ss.ps.state;
    ExprContext *econtext = css->css.ss.ps.ps_ExprContext;
    ResultRelInfo *resultRelInfo = node->resultRelInfo;
    TupleTableSlot *elemTupleSlot = node->elemTupleSlot;
    TupleTableSlot *scanTupleSlot = econtext->ecxt_scantuple;

    Assert(node->type == LABEL_KIND_VERTEX);

    /*
     * Vertices in a path might already exists. If they do get the id
     * to pass to the edges before and after it. Otherwise, insert the
     * new vertex into it's table and then pass the id along.
     */
    if (CYPHER_TARGET_NODE_INSERT_ENTITY(node->flags))
    {
        ResultRelInfo **old_estate_es_result_relations = NULL;

        /*
         * Set estate's result relation to the vertex's result
         * relation.
         *
         * Note: This obliterates what was their previously
         */

        /* save the old result relation info */
        old_estate_es_result_relations = estate->es_result_relations;

        estate->es_result_relations = &resultRelInfo;

        ExecClearTuple(elemTupleSlot);

        /* get the next graphid for this vertex. */
        id = ExecEvalExpr(node->id_expr_state, econtext, &isNull);
        elemTupleSlot->tts_values[vertex_tuple_id] = id;
        elemTupleSlot->tts_isnull[vertex_tuple_id] = isNull;

        /* get the properties for this vertex */
        elemTupleSlot->tts_values[vertex_tuple_properties] =
            scanTupleSlot->tts_values[node->prop_attr_num];
        elemTupleSlot->tts_isnull[vertex_tuple_properties] =
            scanTupleSlot->tts_isnull[node->prop_attr_num];

        /* Insert the new vertex */
        insert_entity_tuple(resultRelInfo, elemTupleSlot, estate);

        /* restore the old result relation info */
        estate->es_result_relations = old_estate_es_result_relations;

        /*
         * When the vertex is used by clauses higher in the execution tree
         * we need to create a vertex datum. When the vertex is a variable,
         * add to the scantuple slot. When the vertex is part of a path
         * variable, add to the list.
         */
        if (CYPHER_TARGET_NODE_OUTPUT(node->flags))
        {
            TupleTableSlot *scantuple;
            PlanState *ps;
            Datum result;

            ps = css->css.ss.ps.lefttree;
            scantuple = ps->ps_ExprContext->ecxt_scantuple;

            /* make the vertex agtype */
            result = make_vertex(id, CStringGetDatum(node->label_name),
                scanTupleSlot->tts_values[node->prop_attr_num]);

            /* append to the path list */
            if (CYPHER_TARGET_NODE_IN_PATH(node->flags))
            {
                css->path_values = lappend(css->path_values,
                                           DatumGetPointer(result));
            }

            /*
             * Put the vertex in the correct spot in the scantuple, so parent
             * execution nodes can reference the newly created variable.
             */
            if (CYPHER_TARGET_NODE_IS_VARIABLE(node->flags))
            {
                scantuple->tts_values[node->tuple_position - 1] = result;
                scantuple->tts_isnull[node->tuple_position - 1] = false;
            }
        }
    }
    else
    {
        agtype *a;
        agtype_value *v;
        agtype_value *id_value;
        TupleTableSlot *scantuple;
        PlanState *ps;

        ps = css->css.ss.ps.lefttree;
        scantuple = ps->ps_ExprContext->ecxt_scantuple;

        /* get the vertex agtype in the scanTupleSlot */
        a = DATUM_GET_AGTYPE_P(scantuple->tts_values[node->tuple_position - 1]);

        /* Convert to an agtype value */
        v = get_ith_agtype_value_from_container(&a->root, 0);

        if (v->type != AGTV_VERTEX)
        {
            ereport(ERROR,
                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                     errmsg("agtype must resolve to a vertex")));
        }

        /* extract the id agtype field */
        id_value = GET_AGTYPE_VALUE_OBJECT_VALUE(v, "id");

        /* extract the graphid and cast to a Datum */
        id = GRAPHID_GET_DATUM(id_value->val.int_value);

        /*
         * Its possible the variable has already been deleted. There are two
         * ways this can happen. One is the query explicitly deleted the
         * variable, the is_deleted flag will catch that. However, it is
         * possible the user deleted the vertex using another variable name. We
         * need to scan the table to find the vertex's current status relative
         * to this CREATE clause. If the variable was initially created in this
         * clause, we can skip this check, because the transaction system
         * guarantees that nothing can happen to that tuple, as far as we are
         * concerned with at this time.
         */
        if (!SAFE_TO_SKIP_EXISTENCE_CHECK(node->flags))
        {
            if (!entity_exists(estate, css->graph_oid, DATUM_GET_GRAPHID(id)))
            {
                ereport(ERROR,
                    (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
                     errmsg("vertex assigned to variable %s was deleted",
                            node->variable_name)));
            }
        }

        if (CYPHER_TARGET_NODE_IN_PATH(node->flags))
        {
            Datum vertex = scanTupleSlot->tts_values[node->tuple_position - 1];
            css->path_values = lappend(css->path_values,
                                       DatumGetPointer(vertex));
        }
    }

    /* If the path continues, create the next edge, passing the vertex's id. */
    if (next != NULL)
    {
        create_edge(css, lfirst(next), id, lnext(list, next), list);
    }

    return id;
}