(1 row) MyTest=# SELECT '1110'::bit(4)::integer; int4 --- 14 (1 row) 注意:如果只是转换为"bit",意思是转换成bit(1),因此只会转换成整数的最低位。六、模式匹配: PostgreSQL中提供了三种实现模式匹配的方法:SQL LIKE操作符,更近一些的SIMILAR TO操作符,和POSIX-风格正则表达式。 1. LIKE: stri...
10),floor(random()*100::int);insert into t2 select generate_series(11,20),'english','AA'||generate_series(1,10),floor(random()*100::int);insert into t2 select generate_series(21,30),'article','AA'||generate_series(1,1...
autovacuum_work_mem=2GB #min 1MB,or-1to use maintenance_work_mem ,加速垃圾回收。 dynamic_shared_memory_type=mmap #thedefaultis the first option vacuum_cost_delay=0#0-100milliseconds,垃圾回收不妥协,极限压力下,减少膨胀可能性。 bgwriter_delay=10ms #10-10000ms between rounds,刷shared buffer脏页...
checkpoint_completion_target = 0.99 # checkpoint target duration, 0.0 - 1.0 ,平滑调度间隔,假设上一个检查点到现在这个检查点之间产生了100个XLOG,则这次检查点需要在产生100*checkpoint_completion_target个XLOG文件的过程中完成。PG会根据这些值来调度平滑检查点。 random_page_cost = 1.0 # same scale as abo...
random_page_cost = 1.0 # same scale as above , 离散扫描的成本因子,本例使用的SSD IO能力足够好 effective_cache_size = 240GB # 可用的OS CACHE log_destination = 'csvlog' # Valid values are combinations of logging_collector = on # Enable capturing of stderr and csvlog ...
18. IF( NEW.id BETWEEN 1 AND 200 ) THEN 19. INSERT INTO childtb_1 VALUES (NEW.*); 20. ( NEW.id BETWEEN 201 AND 400 ) THEN 21. INSERT INTO childtb_2 VALUES (NEW.*); 22. ( NEW.id BETWEEN 401 AND 600 ) THEN 23. INSERT INTO childtb_3 VALUES (NEW.*); ...
total_cost = indexStartupCost + indexTotalCost + cpu_index_tuple_cost * tuples indexTotalCost = random_page_cost * pages 变量解释: indexStartupCost: 索引扫描的启动成本。 indexTotalCost: 索引扫描的总成本。 cpu_index_tuple_cost: 处理每个索引元组的 CPU 成本。 random_page_cost: 随机页面读取...
--产生1-10之间的随机数(包括边缘) --SELECT get_random_number(1, 10); --function for get random date between start_date and end_date -- DROP FUNCTION IF EXISTS get_random_date(date, date); CREATE OR REPLACE FUNCTION get_random_date(start_date date, end_date date) RETURNS integer AS ...
*/status->cur_delay=MIN_DELAY_USEC;pg_usleep(status->cur_delay);#if defined(S_LOCK_TEST)fprintf(stdout,"*");fflush(stdout);#endif/* increase delay by a random fraction between 1X and 2X */status->cur_delay+=(int)(status->cur_delay*((double)random()/(double)MAX_RANDOM_VALUE)+0.5...
(1).比如A表user_id字段数据类型定义为varchar,但是SQL语句查询为 where user_id=1234; 【推荐】如何保证分区表的主键序列全局唯一。 使用多个序列,每个序列的步调不一样,或者每个序列的范围不一样即可。 例如 postgres=# create sequence seq_tab1 increment by 10000 start with 1;CREATE SEQUENCEpostgres=# cr...