文章来源:http://www.ihref.com/read-16422.html1.对查询进行优化,应尽量避免全表扫描,首先应考虑在 where 及 order by 涉及的列上建立索引。2.应尽量避免在 where 子句中对字段进行 null 值判断,否则将导致引擎放弃使用索引而进行全表扫描,Sql 代码 : select id from t where num is null;可以在 num 上...【阅读全文】
Descriptionpg_dump is a utility for backing up a PostgreSQL database. It makes consistent backups even if the database is being used concurrently. pg_dump does not block other users accessing the database (readers or writers).回答来自:http://dba.stackexchange.com/...【阅读全文】