グラフの削除 ● 作成したグラフを削除することも可能 – drop_graph( グラフ名 , フラグ ) – 指定したグラフ内の Vertex と Edge も一緒に消える。 =# SELECT drop_graph('sample', true); NOTICE: drop cascades to 5 other objects DETAIL: drop cascades to table sample._ag_label_vertex drop cascades to table sample._ag_label_edge drop cascades to table sample."Person" drop cascades to table sample."Like" drop cascades to table sample."Dislike" NOTICE: graph "sample" has been dropped drop_graph ------------ (1 row)
-- Create Edge -- From Alice SELECT * FROM cypher('sample', $$ MATCH (a:Person), (b:Person) WHERE a.name = 'Alice' AND b.name = 'Bob' CREATE (a)-[e:Like{level: 'high'}]->(b) RETURN e $$) as (p agtype); SELECT * FROM cypher('sample', $$ MATCH (a:Person), (b:Person) WHERE a.name = 'Alice' AND b.name = 'Erin' CREATE (a)-[e:Dislike{level: 'high'}]->(b) RETURN e $$) as (p agtype); サンプルの Edge 作成（抜粋： Alice 起点） MATCH や WHERE で a,b の Vertex を特定して その間に Edge を作成する
検索（属性を返却） ● Person ノードの name, gender 属性を返却 =# SELECT * FROM cypher('sample', $$ MATCH (a:Person) RETURN a.name, a.gender $$ ) as ("name" text, "gender" text); name | gender -------+-------- Alice | Female Bob | Male Casey | Female Dave | Male Erin | Female (5 rows)
検索（関連を使った MATCH ） ● 好き (Like) で結ばれた Person の name と好き度合い (level) =# SELECT * FROM cypher('sample', $$ MATCH (a:Person)-[e:Like]->(b:Person) RETURN a.name, e.level, b.name $$ ) as ("from" text, "level" text, "to" text); from | level | to -------+-------+------- Alice | high | Bob Bob | high | Erin Casey | high | Dave Dave | high | Alice Erin | mid | Dave Erin | mid | Alice (6 rows)
検索（関連を使った MATCH ） ● Erin(a) の好きな人 (b) が好きなのは誰 (c) ？ =# SELECT * FROM cypher('sample', $$ MATCH (a:Person)-[l:Like]->(b:Person)-[ll:Like]->(c:Person) WHERE a.name = 'Erin' RETURN a.name, b.name, ll.level, c.name $$ ) as ("a" text, "b" text, "level" text, "c" text); a | b | level | c ------+-------+-------+------- Erin | Dave | high | Alice Erin | Alice | high | Bob (2 rows)
Vertex ロード用 CSV ファイルを SQL で生成 ● Vertex はテーブルへの検索結果を CSV 化すれば OK -- extract node data -- extract shop CSV COPY (SELECT sid, status, name, branch, pref, area FROM shops ORDER BY sid) TO '/tmp/shop.csv' CSV; -- extract user CSV COPY (SELECT uid, name FROM users ORDER BY uid) TO '/tmp/user.csv' CSV; -- extract review CSV COPY (SELECT rid, menu, score, category, type, soup, likes, reg_date FROM reviews ) TO '/tmp/review.csv' CSV;
品質はまだ不安・・・ ● WITH, ORDER BY まわりは記述の制約も多いし、 クエリを投げるとクラッシュしたりする・・・ =# SELECT * FROM cypher('ramendb', $$ MATCH (u:User)-[w:write]->(r:Review)<-[comment]-(cu:User),(r)-[eval]->(s:Shop) WITH s, r ORDER BY s.id WHERE r.reg_date >= '2022-01-01' AND r.reg_date <= '2022-06-30' AND s.name = ' ゆで太郎 ' AND r.category = ' そば ' RETURN s.id, r.menu, u.id, cu.id $$ ) as ("area" text, "menu" text, "user id" text, "comment-user id" text); server closed the connection unexpectedly This probably means the server terminated abnormally before or while processing the request. The connection to the server was lost. Attempting reset: Failed. =?> にゃーん・・・
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