shulanxtdb=#CREATETRIGGERexample_trigger AFTERINSERTONCOMPANYFOREACH ROWEXECUTEPROCEDUREauditlogfunc(); auditlogfunc() 是 PostgreSQL 一个程序,其定义如下: CREATEORREPLACEFUNCTIONauditlogfunc()RETURNSTRIGGERAS$example_table$BEGININSERTINTOAUDIT(EMP_ID, ENTRY_DATE)VALUES(new.ID,current_timestamp);RETURNNEW...
Example 11.2. 建立一个部分索引来排除不感兴趣的值 如果我们有一个表包含已上账和未上账的订单,其中未上账的订单在整个表中占据一小部分 且它们是最经常被访问的行。我们可以通过只在未上账的行上创建一个索引来提高性能。创 建索引的命令如下: CREATE INDEX orders_unbilled_index ON orders (order_nr) WHE...
CREATE INDEX c_idx2 ON locktest(c);ALTER TABLE locktest ADD COLUMN c2 INT;CREATE INDEX c2_idx ON locktest(c2);-- unfinished example transaction BEGIN;UPDATE locktest SETc=3WHEREc=1;-- second connectionpostgres=# SELECT * FROM lockview;pid|vxid|lock_type|lock_mode|granted|xid_lock|rel...
1、E = 外部表（由许多外部数据包装器之一提供）2、I = 索引3、m = 物化视图4、s = 序列5、t = 表格6、v = 视图postgres=# \dt List of relations Schema | Name | Type | Owner---+---+---+--- public | example_tbl | table | postgres 4、显示角色和成员 角色用于连接到 ...
使用EXPLAIN分析查询:EXPLAIN SELECT * FROM search_articles('example query'); 用来分析查询的执行计划,找出性能瓶颈。 限制结果数量:如果查询返回大量结果,考虑在SQL查询中使用 LIMIT 和OFFSET。 4. 实战应用 将上述配置和函数应用于实际的Web应用中,可以极大地提升搜索功能的响应速度和准确性。在前端搜索框中输入查...
This tiny bit of code loads 500 million random numeric values, which should be enough to demonstrate, how CREATE INDEX can be improved in PostgreSQL 11. In our example 500 million rows translate to roughly 21 GB of data: ...
《PostgreSQL 垃圾回收原理以及如何预防膨胀 - How to prevent object bloat in PostgreSQL》 《PostgreSQL nagios monitor script (archive, vacuum, age, conn, rollback, standby, lock, xact, seq, index…)》 《PostgreSQL Systemtap example : autovacuum_naptime & databases in cluster》...
For example, if you choose to have one partition per customer and you currently have a small number of large customers, consider the implications if in several years you instead find yourself with a large number of small customers. In this case, it may be better to choose to partition by ...
-- numeric booster example + log(NumberOfVotes)*0.01 FROM movies WHERE search @@ websearch_to_tsquery('english','jedi') ORDER BY rank DESC LIMIT 10; 1. 2. 3. 4. 5. 6. 7. 对数函数用于平滑影响,而0.01因子使得提升与排名得分具有可比性。
CREATE EXTENSION IF NOT EXISTS btree_gin; CREATE EXTENSION IF NOT EXISTS pg_trgm; CREATE INDEX index_users_on_email_gin ON users USING gin (email gin_trgm_ops); 让我们重新运行我们的查询: EXPLAIN ANALYZE SELECT * FROM users WHERE email LIKE '%@example.com'; 代码语言:javascript 代码运行次数...