Edge Types

await graph.add_edge(
    src="/1945/july/16/0529/united-states/new-mexico/los-alamos/trinity-test",
    tgt="/1945/august/6/0815/japan/hiroshima/hiroshima/atomic-bombing-of-hiroshima",
    edge_type="causes",
    weight=1.0
)

-- From db.py:47
type TEXT NOT NULL CHECK (type IN ('causes','contemporaneous','same_location','thematic')),

# From graph.py:426-441
await conn.execute(
    """
    INSERT INTO edges (source, target, type, weight)
    SELECT $1, id, 'contemporaneous', 0.5
    FROM nodes
    WHERE id != $1
      AND year IS NOT NULL
      AND abs(year - $2) <= 1
      AND NOT EXISTS (
          SELECT 1 FROM edges
          WHERE source = $1 AND target = nodes.id AND type = 'contemporaneous'
      )
    """,
    node_id,
    node_year,
)

Apollo 11 Moon Landing (July 20, 1969)
  ↔ [contemporaneous, weight=0.5]
Apollo 12 Lightning Launch (November 14, 1969)

# From graph.py:461-477
await conn.execute(
    """
    INSERT INTO edges (source, target, type, weight)
    SELECT $1, id, 'same_location', 0.5
    FROM nodes
    WHERE id != $1
      AND country = $2 AND region = $3 AND city = $4
      AND NOT EXISTS (
          SELECT 1 FROM edges
          WHERE source = $1 AND target = nodes.id AND type = 'same_location'
      )
    """,
    node_id,
    node_country,
    node_region,
    node_city,
)

Assassination of Julius Caesar (-44, Rome)
  ↔ [same_location, weight=0.5]
Sack of Rome (410, Rome)
  ↔ [same_location, weight=0.5]
Battle of Monte Cassino (1944, Rome region)

# From graph.py:498-516
await conn.execute(
    """
    INSERT INTO edges (source, target, type, weight, theme)
    SELECT $1, n.id, 'thematic', 0.3,
           array_to_string(ARRAY(
               SELECT unnest($2::text[]) INTERSECT SELECT unnest(n.tags)
               ORDER BY 1
           ), ', ')
    FROM nodes n
    WHERE n.id != $1
      AND n.tags && $2::text[]
      AND NOT EXISTS (
          SELECT 1 FROM edges
          WHERE source = $1 AND target = n.id AND type = 'thematic'
      )
    """,
    node_id,
    node_tags,
)

Apollo 11 Moon Landing
  tags: ["space-exploration", "moon-landing", "nasa"]
    ↔ [thematic, weight=0.3, theme="space-exploration, nasa"]
Voyager 1 Jupiter Flyby
  tags: ["space-exploration", "nasa", "planetary-science"]

-- Check for overlap
WHERE n.tags && $2::text[]

-- Calculate shared tags
SELECT unnest($2::text[]) INTERSECT SELECT unnest(n.tags)

# From graph.py:180-184
async def add_edge(self, src: str, tgt: str, edge_type: str, **attrs) -> None:
    if edge_type not in VALID_EDGE_TYPES:
        raise ValueError(
            f"Invalid edge type: {edge_type}. Must be one of {VALID_EDGE_TYPES}"
        )

# From graph.py:11
VALID_EDGE_TYPES = {"causes", "contemporaneous", "same_location", "thematic"}

SELECT source, target, weight FROM edges WHERE type = 'causes';

# From graph.py:317-345
async def get_neighbors(self, node_id: str) -> list[dict]:
    async with self.pool.acquire() as conn:
        rows = await conn.fetch(
            """
            SELECT n.id, n.name, e.type AS edge_type, e.weight, e.theme, 'out' AS direction
            FROM edges e JOIN nodes n ON n.id = e.target
            WHERE e.source = $1
            UNION ALL
            SELECT n.id, n.name, e.type AS edge_type, e.weight, e.theme, 'in' AS direction
            FROM edges e JOIN nodes n ON n.id = e.source
            WHERE e.target = $1
            """,
            node_id,
        )
    return [
        {
            "path": row["id"],
            "name": row["name"],
            "edge_type": row["edge_type"],
            "weight": row["weight"],
            "theme": row["theme"],
        }
        for row in rows
    ]

[
  {
    "path": "/1969/july/20/2017/united-states/florida/cape-canaveral/apollo-11-moon-landing",
    "name": "Apollo 11 Moon Landing",
    "edge_type": "contemporaneous",
    "weight": 0.5,
    "theme": ""
  },
  {
    "path": "/1970/april/13/1913/united-states/florida/cape-canaveral/apollo-13-oxygen-tank-explosion",
    "name": "Apollo 13 Oxygen Tank Explosion",
    "edge_type": "thematic",
    "weight": 0.3,
    "theme": "space-exploration, nasa"
  }
]

# From graph.py:354-356
edge_type_rows = await conn.fetch(
    "SELECT type, count(*) AS cnt FROM edges GROUP BY type"
)

{
  "total_edges": 3421,
  "edge_type_counts": {
    "causes": 87,
    "contemporaneous": 1842,
    "same_location": 923,
    "thematic": 569
  }
}

-- From db.py:50
PRIMARY KEY (source, target, type)

-- Two Apollo missions can have multiple relationships:
INSERT INTO edges (source, target, type, weight) VALUES
  ('apollo-11', 'apollo-12', 'contemporaneous', 0.5),
  ('apollo-11', 'apollo-12', 'thematic', 0.3);