select count(*) from pg_stat_activity; 2、获取数据库最大连接数 show max_connections 3、查询当前连接数详细信息 select * from pg_stat_activity; 4、查询数据库中各个用户名对应的数据库连接数 select usename, count(*) from pg_stat_activity group by usename; 二、赋权操作 1、为指定用户赋予指定...
select * from pg_stat_activity; 4、查询数据库中各个用户名对应的数据库连接数 select usename, count(*) from pg_stat_activity group by usename; 二、赋权操作 1、为指定用户赋予指定表的select权限 GRANT SELECT ON table_name TO username; 2、修改数据库表所属的ownner alter table table_name owner...
1.查下超过10 s的查询语句 select*From pg_stat_activitywherequery_start<=now()- interval'10 sec'and state notin('idle') and pid<>pg_backend_pid() and query ilike'select%'order by query_start ; 2. 超过10s的查询会被干掉 selectpg_terminate_backend(pid) From pg_stat_activitywherequery_st...
From pg_stat_activity where query_start<=now()- interval'10 sec' and state not in ('idle') and pid<>pg_backend_pid() and query ilike 'select%' order by query_start ; 1. 2. 3. 4. 5. 6. 2. 超过10s的查询会被干掉 select pg_terminate_backend(pid) From pg_stat_activity where ...
$SELECT*FROMpg_stat_activity ; datid │ datname │ pid │ leader_pid │ usesysid │ usename │ application_name │ client_addr │ client_hostname │ client_port │ backend_start │ xact_start │ query_start │ state_change │ wait_event_type │ wait_event │ state │ backend_xid │...
gs_guc reload -N all -I all -c "track_stmt_stat_level='OFF,L0'" gs_guc reload -N all -I all -c "instr_unique_sql_count=2000" 3、慢SQL查询 以下是查用的慢SQL查询语句 select * from dbe_perf.get_global_slow_sql_by_timestamp('2024-01-17 00:00:00', '2024-04-17 23:00:00...
与count(distinct)都是很常见的操作。...count(distinct colA)就是将colA中所有出现过的不同值取出来,相信只要接触过数据库的同学都能明白什么意思。...count(distinct colA)的操作也可以用group by的方式完成,具体代码如下: select count(dist...
static int scsi_probe_lun(struct scsi_device *sdev, unsigned char *inq_result, int result_len, int *bflags) { unsigned char scsi_cmd[MAX_COMMAND_SIZE]; int first_inquiry_len, try_inquiry_len, next_inquiry_len; int response_len = 0; int pass, count, result; struct scsi_sense_hdr ...
SELECT * from some_data where (random()*100000000)::int%1000 = 0 order by random() limit 1 where the 1000 you would change as a function of size of your data set so you might replace it with a (SELECT count(id) ..from..) subselect or something like that. ...
在数据库的日常使用中,难免会遇到慢 SQL,遇到慢 SQL 本身并不可怕,困难之处在于如何识别慢 SQL 并对其优化,使它不至于拖慢整个系统的性能,避免危害到日常业务的正常进行。 上期我们讲了索引原因、系统配置和资源竞争导致的慢 SQL,今天我们继续分析和总结。