furyu-tei https://blog.hatena.ne.jp/furyu-tei/ 風柳メモ https://memo.furyutei.com/ これもいままで見過ごしていた… 「SELECT xxx FROM table_a WHERE xxx IN (SELECT xxx FROM table_b ...) 」だと、table_a(xxx)に対して INDEX を作成してあっても Seq Scan になってしまう…？ jcomi_db=# EXPLAIN ANALYZE SELECT COUNT(*) FROM t_author_info WHERE book_info_id IN (SELECT book_info_id FROM t_book_info WHERE book_title LIKE '%ラブひな%'); QUERY… 190 <iframe src="https://hatenablog-parts.com/embed?url=https%3A%2F%2Fmemo.furyutei.com%2Fentry%2F20140120%2F1390226064" title=" PostgreSQL 9.x でサブクエリを使うと Index Scan にならない？ - 風柳メモ" class="embed-card embed-blogcard" scrolling="no" frameborder="0" style="display: block; width: 100%; height: 190px; max-width: 500px; margin: 10px 0px;"></iframe> Hatena Blog https://hatena.blog 2014-01-20 22:54:24 rich https://memo.furyutei.com/entry/20140120/1390226064 1.0 100%