linux 强制释放内存
free -m |grep -i mem |awk '{if($4 < 500){ printf("3") > "/proc/sys/vm/drop_caches"}}'
greenPlum安装mysql_fdw
在greenPlum集群每台机器执行yum install mysql-devel 注意这里安装的是系统自带的mariaDB版本即可，fdw主要使用其中的mysql协议连接器下载mysql_fdw ,注意：该软件主分支已经不支持greenplum 的postgres9.4.26版本了，所以需要用这个版本https://github.com/adam8157/mysql_fdw_greenplum下载到安装greenPlum master机器 后解压然后分别执行make USE_PGXS=1 make USE_PGXS=1 install 执行后生成的文件位置在提示里面是有的so文件在 ...
查询postgres各表的大小
如下：select relname as 表名, reltuples as 记录数 from pg_class where relkind = 'r' and relnamespace = (select oid from pg_namespace where nspname='xxxxx') order by 记录数 desc;
查看postgres正在执行的sql｜关闭指定查询进程
如下：SELECT procpid, START, now() - START AS lap, current_query FROM ( SELECT backendid, pg_stat_get_backend_pid (S.backendid) AS procpid, pg_stat_get_backend_activity_start (S.backendid) AS START, pg_stat_get_backend_activ...
通过sql查询mysql每个表的大小
select table_schema as '数据库', table_name as '表名', table_rows as '记录数', truncate(data_length/1024/1024, 2) as '数据容量(MB)', truncate(index_length/1024/1024, 2) as '索引容量(MB)' from information_schema.tables where table_schema='mysql' order by data_length desc, index_length desc