系統允許的總鎖數

SELECT
(SELECT setting::int FROM pg_settings WHERE name = 'max_locks_per_transaction') *
(SELECT setting::int FROM pg_settings WHERE name = 'max_connections') +
(SELECT setting::int FROM pg_settings WHERE name = 'max_prepared_transactions');

當鎖大于上述數據

dynadot=# SELECT                         
count(    pid)
FROM pg_locks ;count 
-------563
(1 row)

就會出現

 ERROR: out of shared memory

一般是調大max_locks_per_transaction

參考下方的官方文檔。

20.12.?鎖管理

大多數會出現在“查詢一個有很多子表的父表”這種情況，會有大量的鎖。所以此時會報錯。