pg_backend_memory_contexts 是一个 系统目录 视图，显示与当前会话关联的服务器进程的内存上下文用量。这提供了一种可访问的方法来检查各个后端的内存使用情况，而无需附加调试器。
pg_backend_memory_contexts 添加于 PostgreSQL 14 。
按PostgreSQL版本定义
pg_backend_memory_contexts (PostgreSQL 17)
View "pg_catalog.pg_backend_memory_contexts"
Column | Type | Collation | Nullable | Default
---------------+---------+-----------+----------+---------
name | text | | |
ident | text | | |
parent | text | | |
level | integer | | |
total_bytes | bigint | | |
total_nblocks | bigint | | |
free_bytes | bigint | | |
free_chunks | bigint | | |
used_bytes | bigint | | |
pg_backend_memory_contexts (PostgreSQL 16)
View "pg_catalog.pg_backend_memory_contexts"
Column | Type | Collation | Nullable | Default
---------------+---------+-----------+----------+---------
name | text | | |
ident | text | | |
parent | text | | |
level | integer | | |
total_bytes | bigint | | |
total_nblocks | bigint | | |
free_bytes | bigint | | |
free_chunks | bigint | | |
used_bytes | bigint | | |
pg_backend_memory_contexts (PostgreSQL 15)
View "pg_catalog.pg_backend_memory_contexts"
Column | Type | Collation | Nullable | Default
---------------+---------+-----------+----------+---------
name | text | | |
ident | text | | |
parent | text | | |
level | integer | | |
total_bytes | bigint | | |
total_nblocks | bigint | | |
free_bytes | bigint | | |
free_chunks | bigint | | |
used_bytes | bigint | | |
pg_backend_memory_contexts (PostgreSQL 14)
View "pg_catalog.pg_backend_memory_contexts"
Column | Type | Collation | Nullable | Default
---------------+---------+-----------+----------+---------
name | text | | |
ident | text | | |
parent | text | | |
level | integer | | |
total_bytes | bigint | | |
total_nblocks | bigint | | |
free_bytes | bigint | | |
free_chunks | bigint | | |
used_bytes | bigint | | |
变更历史
- PostgreSQL 18
- PostgreSQL 15
- 可以被
pg_read_all_stats成员访问 (提交 77ea4f94)
- 可以被
- PostgreSQL 14
- 添加 (提交 3e98c0ba)；讨论主题：创建用于公开后端进程内存使用情况的函数
示例
postgres=# SELECT name, parent, level, total_bytes, total_nblocks, free_bytes, free_chunks, used_bytes
FROM pg_backend_memory_contexts WHERE name != 'index info';
name | parent | level | total_bytes | total_nblocks | free_bytes | free_chunks | used_bytes
--------------------------+--------------------+-------+-------------+---------------+------------+-------------+------------
TopMemoryContext | | 0 | 68720 | 5 | 14976 | 12 | 53744
TopTransactionContext | TopMemoryContext | 1 | 8192 | 1 | 7720 | 0 | 472
Operator lookup cache | TopMemoryContext | 1 | 24576 | 2 | 10712 | 4 | 13864
Record information cache | TopMemoryContext | 1 | 8192 | 1 | 1536 | 0 | 6656
RowDescriptionContext | TopMemoryContext | 1 | 8192 | 1 | 6880 | 0 | 1312
MessageContext | TopMemoryContext | 1 | 65536 | 4 | 24144 | 0 | 41392
Operator class cache | TopMemoryContext | 1 | 8192 | 1 | 512 | 0 | 7680
smgr relation table | TopMemoryContext | 1 | 16384 | 2 | 4544 | 3 | 11840
TransactionAbortContext | TopMemoryContext | 1 | 32768 | 1 | 32504 | 0 | 264
Portal hash | TopMemoryContext | 1 | 8192 | 1 | 512 | 0 | 7680
TopPortalContext | TopMemoryContext | 1 | 8192 | 1 | 7648 | 0 | 544
PortalContext | TopPortalContext | 2 | 1024 | 1 | 568 | 0 | 456
ExecutorState | PortalContext | 3 | 49216 | 4 | 13040 | 3 | 36176
printtup | ExecutorState | 4 | 8192 | 1 | 7928 | 0 | 264
Table function arguments | ExecutorState | 4 | 8192 | 1 | 7872 | 0 | 320
ExprContext | ExecutorState | 4 | 8192 | 1 | 3336 | 0 | 4856
Relcache by OID | TopMemoryContext | 1 | 16384 | 2 | 3424 | 3 | 12960
CacheMemoryContext | TopMemoryContext | 1 | 524288 | 7 | 104416 | 0 | 419872
relation rules | CacheMemoryContext | 2 | 8192 | 4 | 464 | 0 | 7728
WAL record construction | TopMemoryContext | 1 | 49776 | 2 | 6344 | 0 | 43432
PrivateRefCount | TopMemoryContext | 1 | 8192 | 1 | 2584 | 0 | 5608
MdSmgr | TopMemoryContext | 1 | 8192 | 1 | 7864 | 0 | 328
LOCALLOCK hash | TopMemoryContext | 1 | 8192 | 1 | 512 | 0 | 7680
Timezones | TopMemoryContext | 1 | 104128 | 2 | 2584 | 0 | 101544
ErrorContext | TopMemoryContext | 1 | 8192 | 1 | 7928 | 5 | 264
(25 rows)
参考文献
- PostgreSQL 文档： pg_backend_memory_contexts
有用链接
- pg_backend_memory_contexts - 2023年2月Taraka Vuyyuru / OpenSource DB 博客文章