select 'CREATE VIEW ' || views || E' AS \n'
|| pg_get_viewdef(views, true) as view_definition
from (
select distinct(r.ev_class::regclass) as "views",
pg_class.relname as table_name,
pg_attribute.attname as column_name,
pg_class.dependent_view as rel_obj_name
from pg_depend d join pg_rewrite r on r.oid = d.objid
where refclassid = 'pg_class'::regclass
and refobjid = 'DBNAME.TABLENAME'::regclass
and classid = 'pg_rewrite'::regclass
and pg_get_viewdef(r.ev_class, true) ~ 'COLUMNNAME') as x;
我想运行此查询并在表和列以及其他详细信息上提取viewdefinition(Dependant)。
目前它给出了以下错误：
ERROR: missing FROM-clause entry for table "pg_class" LINE 3: ...(select distinct(r.ev_class::regclass) as "views",pg_class.r... SQL state: 42P01 Character: 162
上述查询中使用的元数据表是：
Table "pg_catalog.pg_class"
Column | Type | Collation | Nullable | Default
---------------------+-----------+-----------+----------+---------
relname | name | | not null |
relnamespace | oid | | not null |
reltype | oid | | not null |
reloftype | oid | | not null |
relowner | oid | | not null |
relam | oid | | not null |
relfilenode | oid | | not null |
reltablespace | oid | | not null |
relpages | integer | | not null |
reltuples | real | | not null |
relallvisible | integer | | not null |
reltoastrelid | oid | | not null |
relhasindex | boolean | | not null |
relisshared | boolean | | not null |
relpersistence | "char" | | not null |
relkind | "char" | | not null |
relnatts | smallint | | not null |
relchecks | smallint | | not null |
relhasoids | boolean | | not null |
relhaspkey | boolean | | not null |
relhasrules | boolean | | not null |
relhastriggers | boolean | | not null |
relhassubclass | boolean | | not null |
relrowsecurity | boolean | | not null |
relforcerowsecurity | boolean | | not null |
relispopulated | boolean | | not null |
relreplident | "char" | | not null |
relfrozenxid | xid | | not null |
relminmxid | xid | | not null |
relacl | aclitem[] | | |
reloptions | text[] | | |
Table "pg_catalog.pg_depend"
Column | Type | Collation | Nullable | Default
------------+---------+-----------+----------+---------
classid | oid | | not null |
objid | oid | | not null |
objsubid | integer | | not null |
refclassid | oid | | not null |
refobjid | oid | | not null |
refobjsubid | integer | | not null |
deptype | "char" | | not null |
Table "pg_catalog.pg_rewrite"
Column | Type | Collation | Nullable | Default
------------+--------------+-----------+----------+---------
rulename | name | | not null |
ev_class | oid | | not null |
ev_type | "char" | | not null |
ev_enabled | "char" | | not null |
is_instead | boolean | | not null |
ev_qual | pg_node_tree | | |
ev_action | pg_node_tree | |
查询1：
SELECT dependent_ns.nspname as dependent_schema
, dependent_view.relname as dependent_view
, source_ns.nspname as source_schema
, source_table.relname as source_table
, pg_attribute.attname as column_name
FROM pg_depend
JOIN pg_rewrite ON pg_depend.objid = pg_rewrite.oid
JOIN pg_class as dependent_view ON pg_rewrite.ev_class = dependent_view.oid
JOIN pg_class as source_table ON pg_depend.refobjid = source_table.oid
JOIN pg_attribute ON pg_depend.refobjid = pg_attribute.attrelid
AND pg_depend.refobjsubid = pg_attribute.attnum
JOIN pg_namespace dependent_ns ON dependent_ns.oid = dependent_view.relnamespace
JOIN pg_namespace source_ns ON source_ns.oid = source_table.relnamespace
WHERE
source_ns.nspname = 'SCHEMANAME'
AND source_table.relname = 'TABLENAME'
AND pg_attribute.attnum > 0
AND pg_attribute.attname = 'COLUMNNAME'
ORDER BY 1,2;
查询2：
select 'CREATE VIEW ' || views || E' AS \n'
|| pg_get_viewdef(views, true) as view_definition
from (select distinct(r.ev_class::regclass) as "views"
from pg_depend d join pg_rewrite r on r.oid = d.objid
where refclassid = 'pg_class'::regclass
and refobjid = 'SCHEMANAME.TABLENAME'::regclass
and classid = 'pg_rewrite'::regclass
and pg_get_viewdef(r.ev_class, true) ~ 'columnname') as x;
如何合并这两个查询以从单个查询中获取名称和视图定义？
我认为这就是你要找的东西：
SELECT v.relnamespace::regnamespace AS dependent_schema
, v.relname AS dependent_table
, t.relnamespace::regnamespace AS source_schema
, t.relname AS source_table
, a.attname AS column_name
, format(E'CREATE VIEW %s AS\n%s'
, v.oid::regclass, pg_get_viewdef(r.ev_class, true)) AS view_definition
FROM pg_class t
JOIN pg_attribute a ON a.attrelid = t.oid
JOIN pg_depend d ON d.refobjid = a.attrelid
AND d.refobjsubid = a.attnum
JOIN pg_rewrite r ON r.oid = d.objid
JOIN pg_class v ON v.oid = r.ev_class
WHERE t.oid = 'SCHEMANAME.TABLENAME'::regclass -- table name HERE
AND a.attname = 'COLUMNAME' -- column name HERE
AND NOT attisdropped -- no dropped cols
AND attnum > 0 -- no system cols
AND d.classid = 'pg_rewrite'::regclass -- it's a view
AND r.ev_type = '1' -- only SELECT
AND r.is_instead; -- INSTEAD rule
比您的任何一个查询更简单，更快速，更安全。但这仍然建立在可能在下一个主要版本中发生变化的实施细节的基础上。所以不要依赖它。
输入（'SCHEMANAME.TABLENAME'）可选地包括模式名称。对于不合格的名字，Postgres默认为search_path。
视图定义使用v.oid::regclass，该模式根据当前的search_path限定视图名称。适应您的需求。
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