PG-监控对象信息SQL语句

１.监视用户表信息

-- 用户表信息
select 
    schemaname as "模式",
    relname as "表名",
    seq_scan as "顺序扫描的次数",
    seq_tup_read as "顺序扫描获取活动行的数量",
    idx_scan as "索引扫描次数",
    idx_tup_fetch as "索引扫描获取活动行的数量",
    n_tup_ins as "累计插入的行数",
    n_tup_upd as "累计更新的行数(包含HOT 更新的行)",    
    n_tup_del as "累计删除的行数",
    n_live_tup as "当前活动行估计数量",
    n_dead_tup as "当前死亡行的估计数量",
    n_mod_since_analyze as "最后一次分析后被修改的行估计数量",
    last_vacuum as "上次被手动清理的时间(不统计VACUUM FULL)",
    last_autovacuum as "上次自动清理的时间",
    last_analyze as "上次手动分析的时间",
    last_autoanalyze as "上次自动清理分析的时间",
    vacuum_count as "手动清理的次数",
    autovacuum_count as "自动清理的次数",
    analyze_count as "手动分析的次数",
    autoanalyze_count as "自动分析的次数",
    pg_size_pretty(pg_table_size(relid)) as "表大小(不包含索引)"
from pg_stat_user_tables
order by 1;

2. 监视用户表IO信息

-- 用户表IO信息
select
    schemaname as "模式",
    relname as "表名",
    heap_blks_read as "读取的磁盘块数量",
    heap_blks_hit as "缓冲区命中数量",
    idx_blks_read as "表上所有索引读取的磁盘块数",
    idx_blks_hit as "表上的所有索引缓冲区命中数量",
    toast_blks_read as "TOAST表(如果有)读取的磁盘块数",
    toast_blks_hit as "TOAST表(如果有)缓冲区命中数量",
    tidx_blks_read as "TOAST表索引(如果有)读取的磁盘块数",
    tidx_blks_hit as "TOAST表索引(如果有)缓冲区命中数量"
from pg_statio_user_tables
order by  1;

3. 监视用户索引信息

-- 用户索引信息
select 
    indexrelid,
    schemaname as "模式",
    relname as "索引所在的表名称",
    indexrelname as "索引名称",
    idx_scan as "索引扫描次数",
    idx_tup_read as "索引扫描返回的索引项数量",
    idx_tup_fetch as "简单索引扫描获取的活动行数量",
    pg_size_pretty(pg_relation_size(indexrelid)) as "索引大小"
from pg_stat_user_indexes
order by 1,2;

4. 计算表的空间大小

-- 计算表的空间大小

select oid,table_schema as "模式",
    table_name as "表名",
    row_estimate::bigint as "表中的行数(估计值)",
    pg_size_pretty(total_bytes) as "总大小",
    pg_size_pretty(table_bytes) as "表大小",
    pg_size_pretty(index_bytes) as "索引大小",
    pg_size_pretty(toast_bytes) as "toast表总大小"    
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'
  ) t1 
) t2 order by 2,3;

附录：

　　１.　参考资料：　https://www.postgresql.org/docs/current/monitoring-stats.html

　　２.　https://blog.csdn.net/kmblack1/article/details/83374910

　　https://wiki.postgresql.org/wiki/Index_Maintenance