1. PostgreSQL DBA日常运维必备SQL大全
作为PostgreSQL数据库管理员，日常工作中需要频繁使用各种SQL来监控数据库状态、排查性能问题、优化资源使用。经过多年实战积累，我整理了一套非常实用的DBA常用SQL集合，涵盖了数据库监控、性能分析、资源优化等各个方面。
这些SQL大多以视图或存储过程的形式存在，可以直接在数据库中创建，方便日常调用。下面我将分类详细介绍这些SQL的使用场景和实现原理。
2. 数据库基础监控视图
2.1 无效索引检查
sql复制CREATE VIEW dba.invalid_index AS
SELECT indisvalid, indexrelid::regclass, indrelid::regclass, pg_get_indexdef(indexrelid)
FROM pg_index
WHERE NOT indisvalid;
这个视图用于检查数据库中所有无效的索引。当索引被标记为无效(indisvalid=false)时，查询优化器会忽略这些索引，但它们仍然占用存储空间。定期检查并删除无效索引可以回收存储空间。
2.2 只读冲突统计
sql复制CREATE VIEW dba.ro_conflicts AS
SELECT datname,
pg_stat_get_db_conflict_all(oid) conflict_all,
pg_stat_get_db_conflict_bufferpin(oid) conflict_bufferpin,
pg_stat_get_db_conflict_lock(oid) conflict_lock,
pg_stat_get_db_conflict_snapshot(oid) conflict_snapshot,
pg_stat_get_db_conflict_startup_deadlock(oid) conflict_deadlock,
pg_stat_get_db_conflict_tablespace(oid) conflict_tbs
FROM pg_database;
该视图显示各数据库发生的冲突统计信息，包括：
- bufferpin冲突：由于缓冲区pin等待导致的冲突
- 锁冲突：由于锁等待导致的冲突
- 快照冲突：由于快照不一致导致的冲突
- 启动死锁：启动过程中的死锁
- 表空间冲突：表空间相关的冲突
高冲突率可能表明应用程序存在并发问题。
2.3 事务处理速率(TPS)监控
sql复制CREATE OR REPLACE PROCEDURE dba.tps() AS $$
DECLARE
v1 int8;
v2 int8;
BEGIN
SELECT txid_snapshot_xmax(txid_current_snapshot()) INTO v1;
COMMIT;
PERFORM pg_sleep(1);
SELECT txid_snapshot_xmax(txid_current_snapshot()) INTO v2;
COMMIT;
RAISE NOTICE 'tps: %', v2-v1;
END;
$$ LANGUAGE plpgsql;
这个存储过程通过比较1秒内事务ID的增长量来计算TPS(每秒事务数)。执行时会输出类似"NOTICE: tps: 125"的信息，表示当前TPS为125。
注意：这种方法计算的是数据库整体TPS，如果需要计算特定应用的TPS，应该使用应用层的监控指标。
3. 复制与高可用监控
3.1 主从复制延迟监控
在主节点上创建以下视图监控复制延迟：
sql复制CREATE VIEW dba.ro_delay AS
SELECT application_name, client_addr, client_port, write_lag, replay_lag, sync_state
FROM pg_stat_replication;
各字段含义：
- write_lag: 主库写入WAL到备库接收WAL的延迟
- replay_lag: 备库接收WAL到应用WAL的延迟
- sync_state: 复制同步状态(同步/异步)
在备节点上创建以下视图监控接收和回放延迟：
sql复制-- 检查备库replay比receive的延迟
CREATE VIEW dba.node_delay AS
SELECT * FROM pg_size_pretty(pg_wal_lsn_diff(pg_last_wal_receive_lsn(), pg_last_wal_replay_lsn())) AS t(delay);
-- 检查备库接收WAL比主库产生WAL的延迟
CREATE VIEW dba.ro_delay_on_standby AS
SELECT pg_size_pretty(pg_wal_lsn_diff(latest_end_lsn, received_lsn))
FROM pg_stat_wal_receiver;
3.2 备库WAL接收和回放带宽监控
sql复制-- 备库WAL接收带宽
CREATE OR REPLACE PROCEDURE dba.wal_receive_bw()
LANGUAGE plpgsql
AS $procedure$
DECLARE
v1 pg_lsn;
v2 pg_lsn;
BEGIN
SELECT pg_last_wal_receive_lsn() INTO v1;
COMMIT;
PERFORM pg_sleep(1);
SELECT pg_last_wal_receive_lsn() INTO v2;
COMMIT;
RAISE NOTICE 'wal receive bw: %/s', pg_size_pretty(pg_wal_lsn_diff(v2,v1));
END;
$procedure$;
-- 备库WAL回放带宽
CREATE OR REPLACE PROCEDURE dba.wal_replay_bw()
LANGUAGE plpgsql
AS $procedure$
DECLARE
v1 pg_lsn;
v2 pg_lsn;
BEGIN
SELECT pg_last_wal_replay_lsn() INTO v1;
COMMIT;
PERFORM pg_sleep(1);
SELECT pg_last_wal_replay_lsn() INTO v2;
COMMIT;
RAISE NOTICE 'wal replay bw: %/s', pg_size_pretty(pg_wal_lsn_diff(v2,v1));
END;
$procedure$;
这两个存储过程分别测量备库接收和应用WAL的速率，对于诊断复制性能问题非常有用。
4. 性能分析与SQL监控
4.1 高耗时SQL查询
sql复制CREATE VIEW dba.topsql AS
SELECT calls, total_time, total_time/calls, query
FROM pg_stat_statements
WHERE query !~ 'rds'
ORDER BY total_time DESC
LIMIT 5;
此视图显示总耗时最高的5条SQL，基于pg_stat_statements扩展收集的统计信息。字段包括：
- calls: 执行次数
- total_time: 总耗时(毫秒)
- total_time/calls: 平均耗时
- query: SQL文本
注意：使用前需确保已安装pg_stat_statements扩展并正确配置。
4.2 QPS(每秒查询数)监控
sql复制CREATE VIEW dba.qps AS
WITH a AS (SELECT sum(calls) s FROM pg_stat_statements),
b AS (SELECT sum(calls) s FROM pg_stat_statements, pg_sleep(1))
SELECT b.s-a.s AS qps FROM a,b;
这个视图通过比较1秒前后SQL执行总数的差值来计算QPS。
4.3 活跃会话监控
sql复制-- 活跃会话数
CREATE VIEW dba.session_acting_cnt AS
SELECT count(*)
FROM pg_stat_activity
WHERE wait_event IS NOT NULL
AND (backend_xid IS NOT NULL OR backend_xmin IS NOT NULL);
-- 活跃会话详情
CREATE VIEW dba.sessions AS
SELECT *
FROM pg_stat_activity
WHERE wait_event IS NOT NULL
AND (backend_xid IS NOT NULL OR backend_xmin IS NOT NULL);
活跃会话数如果持续超过CPU核心数，说明数据库负载较高，可能需要优化。
4.4 锁等待分析
sql复制CREATE VIEW dba.locks AS
WITH t_wait AS (
SELECT a.mode, a.locktype, a.database, a.relation, a.page, a.tuple, a.classid, a.granted,
a.objid, a.objsubid, a.pid, a.virtualtransaction, a.virtualxid, a.transactionid, a.fastpath,
b.state, b.query, b.xact_start, b.query_start, b.usename, b.datname, b.client_addr, b.client_port, b.application_name
FROM pg_locks a, pg_stat_activity b
WHERE a.pid=b.pid AND NOT a.granted
),
t_run AS (
SELECT a.mode, a.locktype, a.database, a.relation, a.page, a.tuple, a.classid, a.granted,
a.objid, a.objsubid, a.pid, a.virtualtransaction, a.virtualxid, a.transactionid, a.fastpath,
b.state, b.query, b.xact_start, b.query_start, b.usename, b.datname, b.client_addr, b.client_port, b.application_name
FROM pg_locks a, pg_stat_activity b
WHERE a.pid=b.pid AND a.granted
),
t_overlap AS (
SELECT r.* FROM t_wait w JOIN t_run r ON
(
r.locktype IS NOT DISTINCT FROM w.locktype AND
r.database IS NOT DISTINCT FROM w.database AND
r.relation IS NOT DISTINCT FROM w.relation AND
r.page IS NOT DISTINCT FROM w.page AND
r.tuple IS NOT DISTINCT FROM w.tuple AND
r.virtualxid IS NOT DISTINCT FROM w.virtualxid AND
r.transactionid IS NOT DISTINCT FROM w.transactionid AND
r.classid IS NOT DISTINCT FROM w.classid AND
r.objid IS NOT DISTINCT FROM w.objid AND
r.objsubid IS NOT DISTINCT FROM w.objsubid AND
r.pid <> w.pid
)
),
t_unionall AS (
SELECT r.* FROM t_overlap r
UNION ALL
SELECT w.* FROM t_wait w
)
SELECT locktype, datname, relation::regclass, page, tuple, virtualxid, transactionid::text, classid::regclass, objid, objsubid,
string_agg(
'Pid: '||CASE WHEN pid IS NULL THEN 'NULL' ELSE pid::text END||chr(10)||
'Lock_Granted: '||CASE WHEN granted IS NULL THEN 'NULL' ELSE granted::text END||' , Mode: '||CASE WHEN mode IS NULL THEN 'NULL' ELSE mode::text END||' , FastPath: '||CASE WHEN fastpath IS NULL THEN 'NULL' ELSE fastpath::text END||' , VirtualTransaction: '||CASE WHEN virtualtransaction IS NULL THEN 'NULL' ELSE virtualtransaction::text END||' , Session_State: '||CASE WHEN state IS NULL THEN 'NULL' ELSE state::text END||chr(10)||
'Username: '||CASE WHEN usename IS NULL THEN 'NULL' ELSE usename::text END||' , Database: '||CASE WHEN datname IS NULL THEN 'NULL' ELSE datname::text END||' , Client_Addr: '||CASE WHEN client_addr IS NULL THEN 'NULL' ELSE client_addr::text END||' , Client_Port: '||CASE WHEN client_port IS NULL THEN 'NULL' ELSE client_port::text END||' , Application_Name: '||CASE WHEN application_name IS NULL THEN 'NULL' ELSE application_name::text END||chr(10)||
'Xact_Start: '||CASE WHEN xact_start IS NULL THEN 'NULL' ELSE xact_start::text END||' , Query_Start: '||CASE WHEN query_start IS NULL THEN 'NULL' ELSE query_start::text END||' , Xact_Elapse: '||CASE WHEN (now()-xact_start) IS NULL THEN 'NULL' ELSE (now()-xact_start)::text END||' , Query_Elapse: '||CASE WHEN (now()-query_start) IS NULL THEN 'NULL' ELSE (now()-query_start)::text END||chr(10)||
'SQL (Current SQL in Transaction): '||chr(10)||
CASE WHEN query IS NULL THEN 'NULL' ELSE query::text END,
chr(10)||'--------'||chr(10)
ORDER BY
(CASE mode
WHEN 'INVALID' THEN 0
WHEN 'AccessShareLock' THEN 1
WHEN 'RowShareLock' THEN 2
WHEN 'RowExclusiveLock' THEN 3
WHEN 'ShareUpdateExclusiveLock' THEN 4
WHEN 'ShareLock' THEN 5
WHEN 'ShareRowExclusiveLock' THEN 6
WHEN 'ExclusiveLock' THEN 7
WHEN 'AccessExclusiveLock' THEN 8
ELSE 0
END) DESC,
(CASE WHEN granted THEN 0 ELSE 1 END)
) AS lock_conflict
FROM t_unionall
GROUP BY locktype, datname, relation, page, tuple, virtualxid, transactionid::text, classid, objid, objsubid;
这个复杂的视图提供了详细的锁等待链信息，包括：
- 锁类型和模式
- 持有锁和等待锁的会话详情
- 会话状态和SQL语句
- 事务开始时间和持续时间
对于排查死锁和锁等待问题非常有用。
4.5 锁等待链分析
sql复制CREATE VIEW dba.v_lock_chains AS
WITH RECURSIVE
a AS (SELECT pid FROM pg_locks WHERE NOT granted),
tmp AS (
SELECT 1 AS id, pid AS blocked_pid, conflict_origin_own_lock_pid
FROM (SELECT pid, unnest(pg_blocking_pids(pid)) AS conflict_origin_own_lock_pid FROM a) tt
UNION ALL
SELECT id+1, conflict_origin_own_lock_pid AS blocked_pid, unnest(pg_blocking_pids(conflict_origin_own_lock_pid)) AS conflict_origin_own_lock_pid
FROM tmp
)
SELECT tmp.id, pg_locks.pid, pg_locks.locktype, pg_locks.mode, pg_locks.granted, pg_stat_activity.query,
tmp.conflict_origin_own_lock_pid
FROM tmp, pg_locks, pg_stat_activity
WHERE tmp.blocked_pid=pg_locks.pid
AND pg_locks.pid = pg_stat_activity.pid
ORDER BY id;
这个视图使用递归CTE分析锁等待链，清晰地展示哪些会话被哪些会话阻塞，对于诊断复杂的锁等待场景特别有用。
5. 数据库对象大小分析
5.1 大表和大索引查询
sql复制-- 查询最大的10张表
CREATE VIEW dba.top10sizetable AS
SELECT schemaname, tablename, pg_size_pretty(pg_relation_size((quote_ident(schemaname)||'.'||quote_ident(tablename))::regclass))
FROM pg_tables
ORDER BY pg_relation_size((quote_ident(schemaname)||'.'||quote_ident(tablename))::regclass) DESC
LIMIT 10;
-- 查询最大的10个索引
CREATE VIEW dba.top10sizeindex AS
SELECT schemaname, tablename, indexname, pg_size_pretty(pg_relation_size((quote_ident(schemaname)||'.'||quote_ident(indexname))::regclass))
FROM pg_indexes
ORDER BY pg_relation_size((quote_ident(schemaname)||'.'||quote_ident(indexname))::regclass) DESC
LIMIT 10;
-- 查询最大的10张表(包含索引大小)
CREATE VIEW dba.top10sizetableindex AS
SELECT schemaname, tablename, pg_size_pretty(pg_total_relation_size((quote_ident(schemaname)||'.'||quote_ident(tablename))::regclass))
FROM pg_tables
ORDER BY pg_total_relation_size((quote_ident(schemaname)||'.'||quote_ident(tablename))::regclass) DESC
LIMIT 10;
这些视图帮助DBA快速识别数据库中占用空间最多的表和索引，便于进行存储容量规划。
5.2 表操作频率分析
sql复制-- 更新/删除最频繁的10张表
CREATE VIEW dba.top10updatetable AS
SELECT schemaname, relname, n_tup_upd, n_tup_del, round(n_tup_hot_upd/(CASE WHEN n_tup_upd=0 THEN 1.0 ELSE n_tup_upd::numeric END),4)
FROM pg_stat_all_tables
ORDER BY n_tup_upd+n_tup_del DESC
LIMIT 10;
-- 插入最频繁的10张表
CREATE VIEW dba.top10inserttable AS
SELECT schemaname, relname, n_tup_ins
FROM pg_stat_all_tables
ORDER BY n_tup_ins DESC
LIMIT 10;
-- 死元组最多的10张表
CREATE VIEW dba.top10deadtable AS
SELECT schemaname, relname, n_dead_tup
FROM pg_stat_all_tables
ORDER BY n_dead_tup DESC
LIMIT 10;
这些视图基于pg_stat_all_tables的统计信息，帮助识别最活跃的表，便于进行针对性的优化。
5.3 事务ID年龄监控
sql复制-- 事务ID年龄最大的10张表
CREATE VIEW dba.top10age AS
SELECT relnamespace::regnamespace, relname, pg_size_pretty(pg_relation_size(oid)), age(relfrozenxid)
FROM pg_class
WHERE relkind='r'
AND relnamespace<>'pg_catalog'::regnamespace
AND relnamespace<>'information_schema'::regnamespace
ORDER BY age(relfrozenxid) DESC, pg_relation_size(oid) DESC
LIMIT 10;
事务ID年龄过大会导致数据库需要执行紧急的FREEZE操作，可能影响性能。这个视图帮助识别风险表。
5.4 最老事务查询
sql复制CREATE VIEW dba.oldestxact AS
SELECT * FROM (
SELECT datname, usename, least(xact_start, query_start) AS least_start,
greatest(age(backend_xid), age(backend_xmin)) AS greatest_age,
now()-least(xact_start, query_start) AS old_ts,
query
FROM pg_stat_activity
WHERE ltrim(lower(query),' ') !~ '^vacuum'
AND NOT (query ~ 'autovacuum' AND backend_type <> 'client backend')
AND pid <> pg_backend_pid()
ORDER BY greatest(age(backend_xid), age(backend_xmin)) DESC NULLS LAST
LIMIT 1
) t1
UNION ALL
SELECT * FROM (
SELECT database, owner, prepared, age(transaction), now()-prepared, '2pc xact: '||gid
FROM pg_prepared_xacts
ORDER BY age(transaction) DESC NULLS LAST
LIMIT 1
) t2;
长时间运行的事务会导致：
- 膨胀：VACUUM无法清理这些事务之前产生的死元组
- 复制延迟：逻辑复制需要等待长事务提交
- 事务ID回卷风险
这个视图帮助识别最老的事务和两阶段提交事务。
6. 表膨胀分析
表膨胀是PostgreSQL中常见的问题，指表中死元组占用过多空间的情况。以下视图帮助识别和量化膨胀问题。
6.1 膨胀空间TOP 10表
sql复制CREATE VIEW dba.top10bloatsizetable AS
SELECT
current_database() AS db, schemaname, tablename, reltuples::bigint AS tups, relpages::bigint AS pages, otta,
ROUND(CASE WHEN otta=0 OR sml.relpages=0 OR sml.relpages=otta THEN 0.0 ELSE sml.relpages/otta::numeric END,1) AS tbloat,
CASE WHEN relpages < otta THEN 0 ELSE relpages::bigint - otta END AS wastedpages,
CASE WHEN relpages < otta THEN 0 ELSE bs*(sml.relpages-otta)::bigint END AS wastedbytes,
CASE WHEN relpages < otta THEN '0 bytes'::text ELSE pg_size_pretty((bs*(relpages-otta))::bigint) END AS wastedsize,
iname, ituples::bigint AS itups, ipages::bigint AS ipages, iotta,
ROUND(CASE WHEN iotta=0 OR ipages=0 OR ipages=iotta THEN 0.0 ELSE ipages/iotta::numeric END,1) AS ibloat,
CASE WHEN ipages < iotta THEN 0 ELSE ipages::bigint - iotta END AS wastedipages,
CASE WHEN ipages < iotta THEN 0 ELSE bs*(ipages-iotta) END AS wastedibytes,
CASE WHEN ipages < iotta THEN '0 bytes' ELSE pg_size_pretty((bs*(ipages-iotta))::bigint) END AS wastedisize,
pg_size_pretty(CASE WHEN relpages < otta THEN
CASE WHEN ipages < iotta THEN 0 ELSE bs*(ipages-iotta::bigint) END
ELSE CASE WHEN ipages < iotta THEN bs*(relpages-otta::bigint)
ELSE bs*(relpages-otta::bigint + ipages-iotta::bigint) END
END) AS totalwastedbytes
FROM (
SELECT
nn.nspname AS schemaname,
cc.relname AS tablename,
COALESCE(cc.reltuples,0) AS reltuples,
COALESCE(cc.relpages,0) AS relpages,
COALESCE(bs,0) AS bs,
COALESCE(CEIL((cc.reltuples*((datahdr+ma-
(CASE WHEN datahdr%ma=0 THEN ma ELSE datahdr%ma END))+nullhdr2+4))/(bs-20::float)),0) AS otta,
COALESCE(c2.relname,'?') AS iname, COALESCE(c2.reltuples,0) AS ituples, COALESCE(c2.relpages,0) AS ipages,
COALESCE(CEIL((c2.reltuples*(datahdr-12))/(bs-20::float)),0) AS iotta -- very rough approximation, assumes all cols
FROM
pg_class cc
JOIN pg_namespace nn ON cc.relnamespace = nn.oid AND nn.nspname <> 'information_schema'
LEFT JOIN (
SELECT
ma,bs,foo.nspname,foo.relname,
(datawidth+(hdr+ma-(case when hdr%ma=0 THEN ma ELSE hdr%ma END)))::numeric AS datahdr,
(maxfracsum*(nullhdr+ma-(case when nullhdr%ma=0 THEN ma ELSE nullhdr%ma END))) AS nullhdr2
FROM (
SELECT
ns.nspname, tbl.relname, hdr, ma, bs,
SUM((1-coalesce(null_frac,0))*coalesce(avg_width, 2048)) AS datawidth,
MAX(coalesce(null_frac,0)) AS maxfracsum,
hdr+(
SELECT 1+count(*)/8
FROM pg_stats s2
WHERE null_frac<>0 AND s2.schemaname = ns.nspname AND s2.tablename = tbl.relname
) AS nullhdr
FROM pg_attribute att
JOIN pg_class tbl ON att.attrelid = tbl.oid
JOIN pg_namespace ns ON ns.oid = tbl.relnamespace
LEFT JOIN pg_stats s ON s.schemaname=ns.nspname
AND s.tablename = tbl.relname
AND s.inherited=false
AND s.attname=att.attname,
(
SELECT
(SELECT current_setting('block_size')::numeric) AS bs,
CASE WHEN SUBSTRING(SPLIT_PART(v, ' ', 2) FROM '#"[0-9]+.[0-9]+#"%' for '#')
IN ('8.0','8.1','8.2') THEN 27 ELSE 23 END AS hdr,
CASE WHEN v ~ 'mingw32' OR v ~ '64-bit' THEN 8 ELSE 4 END AS ma
FROM (SELECT version() AS v) AS foo
) AS constants
WHERE att.attnum > 0 AND tbl.relkind='r'
GROUP BY 1,2,3,4,5
) AS foo
) AS rs
ON cc.relname = rs.relname AND nn.nspname = rs.nspname
LEFT JOIN pg_index i ON indrelid = cc.oid
LEFT JOIN pg_class c2 ON c2.oid = i.indexrelid
) AS sml ORDER BY wastedbytes DESC LIMIT 5;
这个复杂的视图计算了表的膨胀空间，包括：
- 表实际大小与理想大小的比值(tbloat)
- 浪费的页数和字节数
- 索引膨胀情况
- 总浪费空间
6.2 膨胀空间TOP 10索引
sql复制CREATE VIEW dba.top10bloatsizeindex AS
SELECT
current_database() AS db, schemaname, tablename, reltuples::bigint AS tups, relpages::bigint AS pages, otta,
ROUND(CASE WHEN otta=0 OR sml.relpages=0 OR sml.relpages=otta THEN 0.0 ELSE sml.relpages/otta::numeric END,1) AS tbloat,
CASE WHEN relpages < otta THEN 0 ELSE relpages::bigint - otta END AS wastedpages,
CASE WHEN relpages < otta THEN 0 ELSE bs*(sml.relpages-otta)::bigint END AS wastedbytes,
CASE WHEN relpages < otta THEN '0 bytes'::text ELSE pg_size_pretty((bs*(relpages-otta))::bigint) END AS wastedsize,
iname, ituples::bigint AS itups, ipages::bigint AS ipages, iotta,
ROUND(CASE WHEN iotta=0 OR ipages=0 OR ipages=iotta THEN 0.0 ELSE ipages/iotta::numeric END,1) AS ibloat,
CASE WHEN ipages < iotta THEN 0 ELSE ipages::bigint - iotta END AS wastedipages,
CASE WHEN ipages < iotta THEN 0 ELSE bs*(ipages-iotta) END AS wastedibytes,
CASE WHEN ipages < iotta THEN '0 bytes' ELSE pg_size_pretty((bs*(ipages-iotta))::bigint) END AS wastedisize,
pg_size_pretty(CASE WHEN relpages < otta THEN
CASE WHEN ipages < iotta THEN 0 ELSE bs*(ipages-iotta::bigint) END
ELSE CASE WHEN ipages < iotta THEN bs*(relpages-otta::bigint)
ELSE bs*(relpages-otta::bigint + ipages-iotta::bigint) END
END) AS totalwastedbytes
FROM (
SELECT
nn.nspname AS schemaname,
cc.relname AS tablename,
COALESCE(cc.reltuples,0) AS reltuples,
COALESCE(cc.relpages,0) AS relpages,
COALESCE(bs,0) AS bs,
COALESCE(CEIL((cc.reltuples*((datahdr+ma-
(CASE WHEN datahdr%ma=0 THEN ma ELSE datahdr%ma END))+nullhdr2+4))/(bs-20::float)),0) AS otta,
COALESCE(c2.relname,'?') AS iname, COALESCE(c2.reltuples,0) AS ituples, COALESCE(c2.relpages,0) AS ipages,
COALESCE(CEIL((c2.reltuples*(datahdr-12))/(bs-20::float)),0) AS iotta -- very rough approximation, assumes all cols
FROM
pg_class cc
JOIN pg_namespace nn ON cc.relnamespace = nn.oid AND nn.nspname <> 'information_schema'
LEFT JOIN (
SELECT
ma,bs,foo.nspname,foo.relname,
(datawidth+(hdr+ma-(case when hdr%ma=0 THEN ma ELSE hdr%ma END)))::numeric AS datahdr,
(maxfracsum*(nullhdr+ma-(case when nullhdr%ma=0 THEN ma ELSE nullhdr%ma END))) AS nullhdr2
FROM (
SELECT
ns.nspname, tbl.relname, hdr, ma, bs,
SUM((1-coalesce(null_frac,0))*coalesce(avg_width, 2048)) AS datawidth,
MAX(coalesce(null_frac,0)) AS maxfracsum,
hdr+(
SELECT 1+count(*)/8
FROM pg_stats s2
WHERE null_frac<>0 AND s2.schemaname = ns.nspname AND s2.tablename = tbl.relname
) AS nullhdr
FROM pg_attribute att
JOIN pg_class tbl ON att.attrelid = tbl.oid
JOIN pg_namespace ns ON ns.oid = tbl.relnamespace
LEFT JOIN pg_stats s ON s.schemaname=ns.nspname
AND s.tablename = tbl.relname
AND s.inherited=false
AND s.attname=att.attname,
(
SELECT
(SELECT current_setting('block_size')::numeric) AS bs,
CASE WHEN SUBSTRING(SPLIT_PART(v, ' ', 2) FROM '#"[0-9]+.[0-9]+#"%' for '#')
IN ('8.0','8.1','8.2') THEN 27 ELSE 23 END AS hdr,
CASE WHEN v ~ 'mingw32' OR v ~ '64-bit' THEN 8 ELSE 4 END AS ma
FROM (SELECT version() AS v) AS foo
) AS constants
WHERE att.attnum > 0 AND tbl.relkind='r'
GROUP BY 1,2,3,4,5
) AS foo
) AS rs
ON cc.relname = rs.relname AND nn.nspname = rs.nspname
LEFT JOIN pg_index i ON indrelid = cc.oid
LEFT JOIN pg_class c2 ON c2.oid = i.indexrelid
) AS sml ORDER BY wastedibytes DESC LIMIT 5;
这个视图类似于表膨胀视图，但专注于索引膨胀问题。
6.3 膨胀比例TOP 10表和索引
sql复制-- 膨胀比例TOP 10表(浪费空间>10MB)
CREATE VIEW dba.top10bloatratiotable AS
SELECT
current_database() AS db, schemaname, tablename, reltuples::bigint AS tups, relpages::bigint AS pages, otta,
ROUND(CASE WHEN otta=0 OR sml.relpages=0 OR sml.relpages=otta THEN 0.0 ELSE sml.relpages/otta::numeric END,1) AS tbloat,
CASE WHEN relpages < otta THEN 0 ELSE relpages::bigint - otta END AS wastedpages,
CASE WHEN relpages < otta THEN 0 ELSE bs*(sml.relpages-otta)::bigint END AS wastedbytes,
CASE WHEN relpages < otta THEN '0 bytes'::text ELSE pg_size_pretty((bs*(relpages-otta))::bigint) END AS wastedsize,
iname, ituples::bigint AS itups, ipages::bigint AS ipages, iotta,
ROUND(CASE WHEN iotta=0 OR ipages=0 OR ipages=iotta THEN 0.0 ELSE ipages/iotta::numeric END,1) AS ibloat,
CASE WHEN ipages < iotta THEN 0 ELSE ipages::bigint - iotta END AS wastedipages,
CASE WHEN ipages < iotta THEN 0 ELSE bs*(ipages-iotta) END AS wastedibytes,
CASE WHEN ipages < iotta THEN '0 bytes' ELSE pg_size_pretty((bs*(ipages-iotta))::bigint) END AS wastedisize,
pg_size_pretty(CASE WHEN relpages < otta THEN
CASE WHEN ipages < iotta THEN 0 ELSE bs*(ipages-iotta::bigint) END
ELSE CASE WHEN ipages < iotta THEN bs*(relpages-otta::bigint)
ELSE bs*(relpages-otta::bigint + ipages-iotta::bigint) END
END) AS totalwastedbytes
FROM (
SELECT
nn.nspname AS schemaname,
cc.relname AS tablename,
COALESCE(cc.reltuples,0) AS reltuples,
COALESCE(cc.relpages,0) AS relpages,
COALESCE(bs,0) AS bs,
COALESCE(CEIL((cc.reltuples*((datahdr+ma-
(CASE WHEN datahdr%ma=0 THEN ma ELSE datahdr%ma END))+nullhdr2+4))/(bs-20::float)),0) AS otta,
COALESCE(c2.relname,'?') AS iname, COALESCE(c2.reltuples,0) AS ituples, COALESCE(c2.relpages,0) AS ipages,
COALESCE(CEIL((c2.reltuples*(datahdr-12))/(bs-20::float)),0) AS iotta -- very rough approximation, assumes all cols
FROM
pg_class cc
JOIN pg_namespace nn ON cc.relnamespace = nn.oid AND nn.nspname <> 'information_schema'
LEFT JOIN (
SELECT
ma,bs,foo.nspname,foo.relname,
(datawidth+(hdr+ma-(case when hdr%ma=0 THEN ma ELSE hdr%ma END)))::numeric AS datahdr,
(maxfracsum*(nullhdr+ma-(case when nullhdr%ma=0 THEN ma ELSE nullhdr%ma END))) AS nullhdr2
FROM (
SELECT
ns.nspname, tbl.relname, hdr, ma, bs,
SUM((1-coalesce(null_frac,0))*coalesce(avg_width, 2048)) AS datawidth,
MAX(coalesce(null_frac,0)) AS maxfracsum,
hdr+(
SELECT 1+count(*)/8
FROM pg_stats s2
WHERE null_frac<>0 AND s2.schemaname = ns.nspname AND s2.tablename = tbl.relname
) AS nullhdr
FROM pg_attribute att
JOIN pg_class tbl ON att.attrelid = tbl.oid
JOIN pg_namespace ns ON ns.oid = tbl.relnamespace
LEFT JOIN pg_stats s ON s.schemaname=ns.nspname
AND s.tablename = tbl.relname
AND s.inherited=false
AND s.attname=att.attname,
(
SELECT
(SELECT current_setting('block_size')::numeric) AS bs,
CASE WHEN SUBSTRING(SPLIT_PART(v, ' ', 2) FROM '#"[0-9]+.[0-9]+#"%' for '#')
IN ('8.0','8.1','8.2') THEN