Use none? instead of count.zero? #1030
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`taggings.count.zero?` executes the following sql `SELECT COUNT(*) FROM taggings WHERE taggings.tag_id = ?` This can be very slow on large tables by using `taggings.none?` it instead executes: `SELECT 1 AS one FROM taggings WHERE taggings.tag_id = 304185392 LIMIT 1` which can always use the primary key index and is much faster.
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We have run in to a performance issue when removing unused tags and not using the
tags_countertaggings.count.zero?executes the following sql`SELECT COUNT(*) FROM taggings WHERE taggings.tag_id = ?`This can be very slow on large tables
by using
taggings.none?it instead executes:`SELECT 1 AS one FROM taggings WHERE taggings.tag_id = 304185392 LIMIT 1`which can always use the index and is much faster.