Support Functions for AGE to CSV and Vice Versa

[safi50]

Function Results:

• Stored agload_test_graph data with 72,500 edges and 72,500 vertices from AGE to CSV in 1.2 seconds.
• Loadedagloa_test_graph data 72,500 edges and 72,500 vertices from CSV to AGE graph in 2.5 seconds

Graphs with Nested Properties:

• Stored a nested graph with complex properties containing 100,000 vertices and 50,000 edges from AGE to CSV in 2.7 seconds
• Loaded the same nested graph with 100k vertices and 50k edges from CSV to AGE in 3.0 seconds.

Store Age to CSV Function - Description:

• This function exports the specified graph from AGE to CSV files.
• If a vertex or node has nested properties, it is loaded to a JSON file instead.
• The Function fetched data directly from the AGE tables bypassing Cypher queries.

Parameters:

    - conn: A psycopg2 connection object to Postgres.
        Example:
            conn = psycopg2.connect(host="", 
                                database="", 
                                user="", 
                                password="")

    - graph_name: The name of the graph to be exported.
    - path: The directory path where the exported CSV/JSON files will be saved.

• The function throws an exception if any errors occur during the export process.

Store CSV to AGE Function - Description

• This function loads CSV / JSON data into an Apache AGE graph database.
• Data should be appropriately formatted for the function to work.
• If a vertex or an edge contains nested properties, it will be stored in JSON file instead of CSV.

FOR CSV FILES:

• In Vertex Files: atleast 1 column named as 'id' is required.
• In Edge Files: Following Columns are required:
  1. 'start_id', 2. 'end_id', 3. 'start_vertex_type', 4. 'end_vertex_type'

FOR JSON FILES:

• For Vertex Files: The JSON file should contain a key named 'id' for each vertex.
• For Edge Files: The JSON file should contain keys named as following:
  1. 'start_id', 2. 'end_id', 3. 'start_vertex_type', 4. 'end_vertex_type' for each edge.

NOTE: In CSV and JSON files, additional columns and keys respectively will count as properties.

• The function also supports bulk data loading to improve performance.
• The function throws an exception if any errors occur during the loading process.

Parameters:

conn: ext.connection - The database connection object.
graph_name: str - The name of the Apache AGE graph.
path: str - The path to the CSV or JSON file or directory containing such files.
with_labels: bool - An optional argument which specifies whether
                     new labels should be created in the database. 
- Default value  for with_labels is True.

• If with_labels is False , function assumes that vlabels and elabels already exist.

NOTE: Set with_labels to False if you are loading data to an existing graph.

Raises:
Exception: An exception is raised if the given path is neither a file nor a directory
or if the file format is invalid.