问题
磁盘空间不够了，要删除一些历史数据，后面换T级别的硬盘吧
解决过程
备份
硬盘有价，数据无价，在开始删除前，请先做个完整备份，万一以后要查呢。
/usr/bin/pg_dump -U ${zabbix_user} ${zabbix_dbname} | bzip2 -c > zabbix_pgsql_backup_20170309.dump.bz2统计各个表大小
登入PostgreSQL
PGPASSWORD=xxxx /usr/bin/psql -U zabbix统计大小
SELECT *, pg_size_pretty(total_bytes) AS total
, pg_size_pretty(index_bytes) AS INDEX
, pg_size_pretty(toast_bytes) AS toast
, pg_size_pretty(table_bytes) AS TABLE
FROM (
SELECT *, total_bytes-index_bytes-COALESCE(toast_bytes,0) AS table_bytes FROM (
SELECT c.oid,nspname AS table_schema, relname AS TABLE_NAME
, c.reltuples AS row_estimate
, pg_total_relation_size(c.oid) AS total_bytes
, pg_indexes_size(c.oid) AS index_bytes
, pg_total_relation_size(reltoastrelid) AS toast_bytes
FROM pg_class c
LEFT JOIN pg_namespace n ON n.oid = c.relnamespace
WHERE relkind = 'r'
) a
) a;删除方法一
无论表有没有做分区，都可以使用此方法
执行下面的SQL
DELETE FROM history WHERE itemid NOT IN (SELECT itemid FROM items WHERE status='0');
DELETE FROM history_uint WHERE itemid NOT IN (SELECT itemid FROM items WHERE status='0');
DELETE FROM history_str WHERE itemid NOT IN (SELECT itemid FROM items WHERE status='0');
DELETE FROM history_text WHERE itemid NOT IN (SELECT itemid FROM items WHERE status='0');
DELETE FROM history_log WHERE itemid NOT IN (SELECT itemid FROM items WHERE status='0');
DELETE FROM trends WHERE itemid NOT IN (SELECT itemid FROM items WHERE status='0');
DELETE FROM trends_uint WHERE itemid NOT IN (SELECT itemid FROM items WHERE status='0');删除后，手动执行下回收空间
# trends_uint为表名
VACUUM (VERBOSE,ANALYZE) trends_uint;此法存在问题，就是删除时间比较长，容易引起锁表，并导致Zabbix无法使用
查询是否锁表
SELECT relation::regclass, * FROM pg_locks WHERE NOT GRANTED;
更多请参考：burner1024/zabbix-sql
删除方法二
此方法适用于表做了分区，我们采用删除分区的方式，特点是快，就好像删除文件一样快，我怀疑PostgreSQL是不是一个分区就存一个文件
# 显示Schema的搜索路径
SHOW search_path;
# 从上面的输出可以看出，默认没有partitions，我们加入，如果不加入，在drop table的时候，就会提示does not exist
SET search_path TO "$user",partitions,public;
# 可以drop了，CASCADE的作用是把关联的触发条件删除，这触发条件，其实就是什么数据应该插入此分区的，现在已经是2017了，自然不会有2015的数据需要插入，所以可以放心删除
drop table history_uint_2015_01_11 CASCADE;
此法真是快到没朋友，最后 ，简单粗暴，根据上面统计出的表大小结果，我们来批量生成SQL，此处删除2015年的
grep _2015_ zabbix_table_size.txt |awk -F\| '{print "drop table" $3 "CASCADE;"}'其他参考资料：
从下面的参考资料可以看出，自动创建分区，连删除分区，都是自动的