有沒有辦法顯示用戶定義的 postgresql 枚舉類型定義？

Question

假設我們已經定義了一個 postgresql 類型：

CREATE TYPE my_type AS ENUM('foo', 'bar');

有沒有辦法在創建后顯示類型定義？

我希望“\\d my_type”向我展示“ENUM('foo', 'bar')”，但它說：

Did not find any relation named "my_type"

pg_type 表似乎沒有提供足夠的信息。

Answer 1

檢查一下：

select enum_range(null::my_type)

我認為這是一個更簡單的解決方案:)。

Answer 2

它是你所追求的，但並沒有將它作為“創建”聲明。 您對域使用\\ dD。

\dT+ action.action_status
                          List of data types
 Schema |         Name         | Internal name | Size | Elements | Description 
--------+----------------------+---------------+------+----------+-------------
 action | action.action_status | action_status | 4    | pending +| 
        |                      |               |      | live    +| 
        |                      |               |      | done    +| 
        |                      |               |      | notdone  | 
(1 row)

Answer 3

如果您只需要全名（類型名稱和架構）以及所有enum標簽的排序列表，則此查詢將執行以下操作：

SELECT n.nspname AS "schema", t.typname
     , string_agg(e.enumlabel, '|' ORDER BY e.enumsortorder) AS enum_labels
FROM   pg_catalog.pg_type t 
JOIN   pg_catalog.pg_namespace n ON n.oid = t.typnamespace 
JOIN   pg_catalog.pg_enum e ON t.oid = e.enumtypid  
WHERE  t.typname = 'my_enum_type'
GROUP  BY 1,2;

返回：

 schema | typname      | enum_labels
--------+--------------+-------------
 public | my_enum_type | foo|bar

string_agg()需要Postgres 9.0或更高版本，替換為舊版本的array_agg() 。

---

要獲取SQL CREATE語句，可以使用pg_dump並查看轉儲文件。

或者，實際上，使用pgAdmin為數據庫中的任何對象顯示反向工程SQL創建腳本。 在object browser選擇它，其創建腳本將顯示在SQL pane 。 甚至可以選擇將腳本自動復制到新打開的SQL editor窗口，您可以在其中編輯和執行它。

Answer 4

SELECT t.typname
FROM pg_class c JOIN pg_attribute a ON c.oid = a.attrelid JOIN pg_type t ON a.atttypid = t.oid
WHERE c.relname = 'your_type';

棘手的部分是，只需從這些視圖中選擇*，就不會在結果中獲得OID。

Answer 5

使用這篇文章，我已經歸檔了在 PgAdmin 和 PgBackup 中模仿“CREATE TYPE”的目標

WITH types AS (
    SELECT n.nspname,
            pg_catalog.format_type ( t.oid, NULL ) AS obj_name,
            CASE
                WHEN t.typrelid != 0 THEN CAST ( 'tuple' AS pg_catalog.text )
                WHEN t.typlen < 0 THEN CAST ( 'var' AS pg_catalog.text )
                ELSE CAST ( t.typlen AS pg_catalog.text )
                END AS obj_type,
            coalesce ( pg_catalog.obj_description ( t.oid, 'pg_type' ), '' ) AS description
        FROM pg_catalog.pg_type t
        JOIN pg_catalog.pg_namespace n
            ON n.oid = t.typnamespace
        WHERE ( t.typrelid = 0
                OR ( SELECT c.relkind = 'c'
                        FROM pg_catalog.pg_class c
                        WHERE c.oid = t.typrelid ) )
            AND NOT EXISTS (
                    SELECT 1
                        FROM pg_catalog.pg_type el
                        WHERE el.oid = t.typelem
                        AND el.typarray = t.oid )
            AND n.nspname <> 'pg_catalog'
            AND n.nspname <> 'information_schema'
            AND n.nspname !~ '^pg_toast'
),
cols AS (
    SELECT n.nspname::text AS schema_name,
            pg_catalog.format_type ( t.oid, NULL ) AS obj_name,
            a.attname::text AS column_name,
            pg_catalog.format_type ( a.atttypid, a.atttypmod ) AS data_type,
            a.attnotnull AS is_required,
            a.attnum AS ordinal_position,
            pg_catalog.col_description ( a.attrelid, a.attnum ) AS description
        FROM pg_catalog.pg_attribute a
        JOIN pg_catalog.pg_type t
            ON a.attrelid = t.typrelid
        JOIN pg_catalog.pg_namespace n
            ON ( n.oid = t.typnamespace )
        JOIN types
            ON ( types.nspname = n.nspname
                AND types.obj_name = pg_catalog.format_type ( t.oid, NULL ) )
        WHERE a.attnum > 0
            AND NOT a.attisdropped
)
SELECT 'CREATE TYPE ' || cols.schema_name || '.' || cols.obj_name || E' AS (\n    ' ||
pg_catalog.array_to_string (ARRAY( 
    SELECT cols.column_name || ' ' || cols.data_type AS col_num_typ
    FROM cols
    WHERE cols.obj_name='my_user_data_type'
    ORDER BY cols.schema_name,
            cols.obj_name,
            cols.ordinal_position ), E',\n    '
    ) || E'\n);'
AS cre_typ
FROM cols
WHERE cols.obj_name='my_user_data_type'
LIMIT 1

並使用此命令在 psql 下運行它以只有 SQL 代碼：

\\t\\a\\g\\a\\t