Question

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)。

当前它给出以下错误：

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

以上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查看定义？

Answer 1

我认为这就是您要寻找的东西

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

比任何一个查询更简单，更快，更安全。但这仍基于实施细节，这些细节可能在下一个主要版本中有所变化。所以不要依赖它。

输入（'SCHEMANAME.TABLENAME'）可选地包含架构名称。对于不合格的名称，Postgres默认为search_path。

视图定义使用v.oid::regclass，该模式根据当前search_path限定视图名称。适应您的需求。

查询以获取给定表列的依赖视图定义和详细信息

1 个答案: