獲取postgresql數據庫中的分區數

Question

獲取數據庫中創建的分區數的最有效方法是什麼？ 我正在使用* postgresq * l APi for C++。

Answer 1

這是你可以選擇的表分區的所有名稱：

SELECT 
    nmsp_parent.nspname AS parent_schema, 
    parent.relname  AS parent, 
    nmsp_child.nspname AS child, 
    child.relname  AS child_schema 
FROM pg_inherits 
    JOIN pg_class parent  ON pg_inherits.inhparent = parent.oid 
    JOIN pg_class child   ON pg_inherits.inhrelid = child.oid 
    JOIN pg_namespace nmsp_parent ON nmsp_parent.oid = parent.relnamespace 
    JOIN pg_namespace nmsp_child ON nmsp_child.oid = child.relnamespace 

它可以用來計數以及：

SELECT 
    nmsp_parent.nspname  AS parent_schema, 
    parent.relname   AS parent, 
    COUNT(*) 
FROM pg_inherits 
    JOIN pg_class parent  ON pg_inherits.inhparent = parent.oid 
    JOIN pg_class child  ON pg_inherits.inhrelid = child.oid 
    JOIN pg_namespace nmsp_parent ON nmsp_parent.oid = parent.relnamespace 
    JOIN pg_namespace nmsp_child ON nmsp_child.oid = child.relnamespace 
GROUP BY 
    parent_schema, 
    parent; 

Answer 2

^{這個問題是舊的。但a new question on dba.SE引用它，我覺得不得不添加一個更簡單的解決方案。}

據的問題，到...

獲得在數據庫中創建的分區數：

使用inheritance和特定父表，我想：

SELECT count(*) AS partitions 
FROM pg_inherits i 
WHERE i.inhparent = 'my_schema.my_parent_tbl'::regclass; 

有關dba.SE的相關答案更多的細節：
Get all partition names for a table