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本文介紹了在云原生數(shù)據(jù)倉庫 AnalyticDB PostgreSQL 版中，修改被視圖依賴的基表和視圖時面臨的限制，分析此類修改對依賴視圖產(chǎn)生的影響，以及如何快速且安全地修改某個基表結構或視圖。

注意事項

本功能僅支持AnalyticDB PostgreSQL 7.0版實例。
本文涉及的視圖均為依賴于基表的依賴視圖。

查看基表和視圖的依賴關系

若您要查看基表和視圖的依賴關系，需要創(chuàng)建查詢依賴信息的函數(shù)，以如下圖所示的基表和視圖為例，為您介紹如何查看基表和視圖的依賴關系。

使用如下SQL語句創(chuàng)建上圖基表和依賴視圖。

CREATE TABLE cities(id INT, name TEXT, info TEXT);
CREATE TABLE products(id INT, info TEXT);
CREATE TABLE sales(product_id INT, city_id INT, money NUMERIC(10,2));
CREATE VIEW all_info AS SELECT * FROM cities c JOIN sales s ON c.id = s.city_id;
CREATE VIEW ps_info AS SELECT * FROM products p JOIN sales s ON p.id = s.product_id;
CREATE VIEW psc_info AS SELECT * FROM  all_info a JOIN ps_info p ON p.product_id = s.product_id;

使用如下所示SQL語句創(chuàng)建用于查詢依賴信息的函數(shù)。

CREATE OR REPLACE FUNCTION get_table_dependencies(input_schema TEXT, input_table TEXT)
RETURNS TABLE(
    depth INT, 
    dependent_schema TEXT,
    dependent_view TEXT,
    dependent_oid OID,
    source_schema TEXT,
    source_table TEXT
) AS $$
BEGIN
    RETURN QUERY
    WITH RECURSIVE find_views AS (
      SELECT DISTINCT                               
        n.nspname::TEXT as dependent_schema,    -- 確保列是TEXT類型
        cl.relname::TEXT as dependent_view,    -- 轉換為TEXT類型
        cl.oid as dependent_oid,  -- 將OID轉換為TEXT
        nb.nspname::TEXT as source_schema,    -- 轉換為TEXT類型
        c.relname::TEXT as source_table,     -- 轉換為TEXT類型
        1 as depth
      FROM
        pg_depend d
        JOIN pg_rewrite r ON d.objid = r.oid
        JOIN pg_class cl ON r.ev_class = cl.oid
        JOIN pg_class c ON d.refobjid = c.oid
        JOIN pg_namespace n ON cl.relnamespace = n.oid
        JOIN pg_namespace nb ON c.relnamespace = nb.oid
      WHERE
        d.deptype = 'n'
        AND d.classid='pg_rewrite'::regclass
        AND cl.relkind IN ('v', 'm') 
        AND nb.nspname = input_schema
        AND c.relname = input_table
      UNION ALL
        SELECT                               
          n.nspname::TEXT,
          cl.relname::TEXT,
          cl.oid,
          nb.nspname::TEXT,
          c.relname::TEXT,
          fv.depth + 1
        FROM
          pg_depend d
          JOIN pg_rewrite r ON d.objid = r.oid
          JOIN pg_class cl ON r.ev_class = cl.oid
          JOIN pg_class c ON d.refobjid = c.oid
          JOIN pg_namespace n ON cl.relnamespace = n.oid
          JOIN pg_namespace nb ON c.relnamespace = nb.oid
          JOIN find_views fv ON fv.dependent_oid = c.oid
        WHERE
          d.deptype = 'n'
          AND d.classid='pg_rewrite'::regclass
          AND cl.relkind IN ('v', 'm') 
          AND cl.oid <> c.oid
    )
    SELECT DISTINCT fv.depth, fv.dependent_schema, fv.dependent_view, fv.dependent_oid, fv.source_schema, fv.source_table
    FROM find_views fv
    ORDER BY fv.depth;
END;
$$ LANGUAGE plpgsql;

參數(shù)說明如下。

參數(shù)	說明
depth	對中間視圖或基表的依賴層級，直接依賴基表的視圖depth為 1。
dependent_schema	查詢出來的依賴視圖所在的schema。
dependent_view	查詢出來的依賴視圖名。
dependent_oid	依賴視圖的oid。
source_schema	被依賴表或視圖所在的 schema。
source_table	被依賴表或依賴視圖的名稱。

使用如下SQL語句即可查詢上圖基表與依賴視圖的關系。

AS SELECT * FROM get_table_dependencies('public', 'sales');

 depth | dependent_schema | dependent_view | dependent_oid | source_schema | source_table 
-------+------------------+----------------+---------------+---------------+--------------
     1 | public           | all_info       |         26635 | public        | sales
     1 | public           | ps_info        |         26644 | public        | sales
     2 | public           | psc_info       |         26648 | public        | all_info
     2 | public           | psc_info       |         26648 | public        | ps_info
(4 ROWS)

修改基表或視圖的限制

修改基表的限制

修改基表中被引用的數(shù)據(jù)類型，視圖數(shù)據(jù)類型無法被識別。
創(chuàng)建依賴視圖時，視圖每一列的類型已經(jīng)被記錄在系統(tǒng)表中，因此如果修改基表中被引用的數(shù)據(jù)類型，依賴視圖對應列的數(shù)據(jù)類型無法被識別，沒有被引用的基表字段則不受影響。
修改基表中被引用的列，視圖列名不會改變。
創(chuàng)建依賴視圖時，系統(tǒng)表中存儲的是基表列名的序號依賴。修改基表列名不會影響依賴判斷，因此調(diào)整基表列名后，依賴視圖的列名不會隨之更改，原列名的序號關系已經(jīng)在系統(tǒng)表中被記錄。
刪除基表中被引用的列，視圖會被刪除。
若使用Cascade級聯(lián)刪除，會將引用該列的依賴視圖一并刪除。

更多基表DDL限制，請參見下表。

ALTER DDL	有無影響	備注
RENAME	無影響	查詢依賴視圖的定義時，被依賴的基表或中間視圖的重命名會隨之更新。
RENAME COLUMN	無影響	查詢依賴視圖定義時，對應的SELECT列更新，但對應視圖本身的列名不會修改。
RENAME CONSTRAINT	無影響	重命名約束。
SET SCHEMA	無影響	查詢依賴視圖的定義時，會自動更新SCHEMA信息。
ATTACH PARTITION	無影響	無
DETACH PARTITION	無影響	無
DROP COLUMN 引用列	有影響	級聯(lián)刪除直接刪除視圖。
ALTER COLUMN TYPE	有影響	語法級別限制。
ALTER COLUMN SET DEFAULT	無影響	無
ALTER COLUMN DROP DEFAULT	無影響	無
ALTER COLUMN SET/DROP NOT NULL	無影響	無
ALTER COLUMN ADD/SET/DROP GENERATED AS IDENTITY	無影響	將某列轉換為自增列。
ALTER COLUMN SET STATISTICS	無影響	無
ALTER COLUMN RESET/SET ( attribute_option = value)	無影響	無
ALTER COLUMN SET STORAGE	無影響	無
ADD table_constraint	無影響	無
DROP table_constraint	無影響	無
ADD table_constraint_using_index	無影響	無
ENABLE TRIGGER	無影響	無
ENABLE RULE	無影響	無
INHERIT	無影響	無
REDACTION POLICY	無影響	取決于最終查詢?nèi)说臋嘞蕖?/p>

修改視圖的限制

視圖的修改與基表不同，針對視圖的ALTER命令僅能用于修改列的DEFAULT值，常見的修改方式是使用CREATE OR REPLACE的方式對視圖重建。

禁止新增或刪除視圖的任何列。
新增或刪除視圖的任何列相當于重新更新了視圖定義，就算該列沒有被引用，列與基表對應的序號關系也改變了，這會導致系統(tǒng)表中記錄的依賴關系不可用，所以該行為被禁止。
允許新增視圖的追加列。
允許使用CREATE OR REPLACE新增視圖的追加列，追加列對已有列順序沒有影響，依賴的視圖仍舊可以通過系統(tǒng)表信息找到對應的列，因此該操作可正常執(zhí)行。
禁止刪除視圖尾列。
視圖禁止刪除尾列。
禁止修改視圖某一列的數(shù)據(jù)類型。
視圖不允許修改列字段名。

更多視圖修改限制，請參見下表。

結構變更	有無影響	備注
新增某一中間列	有影響	直接修改中間視圖定義來新增列，且有視圖依賴該中間視圖時會被禁止。
新增追加列	無影響	無
刪除列	有影響	直接修改中間視圖定義來刪除列，且有視圖依賴該中間視圖時會被禁止。
修改引用列數(shù)據(jù)類型	有影響	沒有被引用的字段沒有影響。
修改字段名	有影響	中間視圖不允許修改列字段名。

修改基表或視圖

修改步驟

導出視圖相關DDL（根據(jù)實際情況選擇下面一種方式）。
- 修改public.test 基表或中間視圖列b的數(shù)據(jù)類型：執(zhí)行 SELECT record_dependency_ddl('public','test','b')導出相關依賴視圖的DDL信息。
- 刪除public.test 基表引用列 b：執(zhí)行SELECT record_dependency_ddl ('public','test','b') 導出相關依賴視圖的DDL信息。
- 在中間視圖的非末尾處增加列：獲取與該視圖相關的所有依賴視圖，執(zhí)行SELECT record_dependency_ddl('public','test','')導出相關依賴視圖的DDL信息。
- 在中間視圖中刪除列：獲取與該視圖相關的所有依賴視圖，執(zhí)行SELECT record_dependency_ddl('public','test','')導出相關依賴視圖的DDL信息。
- 修改中間視圖的某列字段名：獲取與該視圖相關的所有依賴視圖，執(zhí)行SELECT record_dependency_ddl('public','test','')導出相關依賴視圖的DDL信息。
- DROP DDL和CREATE DDL：DROP DDL可以在臨時表temp_drop_dependency_ddl查看，CREATE DDL可在temp_create_dependency_ddl查看。
- 執(zhí)行record_dependency_ddl函數(shù)：每次執(zhí)行record_dependency_ddl函數(shù)，臨時表信息都將被刷新。臨時表只存在于當前session中，斷連或切換數(shù)據(jù)庫都將消失。
執(zhí)行DROP命令。
使用SELECT drop_dependency_table()來執(zhí)行DROP DDL。若DROP失敗，可嘗試查看臨時表temp_drop_dependency_ddl并手動執(zhí)行。
執(zhí)行基表類型修改或新增列修改。
執(zhí)行CREATE命令（根據(jù)實際情況選擇下面的一種方式）。
- 修改public.test 基表或中間視圖列b的數(shù)據(jù)類型：使用SELECT create_dependency_table()執(zhí)行CREATE DDL。若CREATE失敗，可嘗試查看臨時表temp_create_dependency_ddl并手動執(zhí)行。
- 對public.test 基表刪除引用列b：查看臨時表temp_create_dependency_ddl ，修改引用列b的依賴視圖DDL并手動執(zhí)行。
- 在中間視圖的非末尾處增加列：使用SELECT create_dependency_table()執(zhí)行CREATE ddl，若CREATE失敗，可嘗試查看臨時表temp_create_dependency_ddl并手動執(zhí)行。
- 在中間視圖中刪除列：該列未被其它視圖依賴，使用SELECT create_dependency_table()執(zhí)行CREATE DDL，若CREATE失敗，可嘗試查看臨時表temp_create_dependency_ddl并手動執(zhí)行。
- 在中間視圖中刪除列：該列被其它視圖依賴，查看臨時表temp_create_dependency_ddl ，修改引用該列的依賴視圖的DDL信息并手動執(zhí)行。
- 修改中間視圖的某列字段名：該列未被其它視圖依賴，使用SELECT create_dependency_table()執(zhí)行CREATE DDL，若CREATE失敗，可嘗試查看臨時表temp_create_dependency_ddl并手動執(zhí)行。
- 修改中間視圖的某列字段名：該列被其它視圖依賴，查看臨時表temp_create_dependency_ddl ，修改引用該列的依賴視圖的DDL信息并手動執(zhí)行。

使用示例

以如下圖所示的基表和視圖為例，為您舉例如何安全修改基表和視圖。

執(zhí)行如下SQL命令創(chuàng)建基表和視圖。

CREATE TABLE test(a INT, b INT, c INT);
CREATE VIEW v1 AS SELECT a, b FROM test;
CREATE VIEW  v2 AS SELECT b, c FROM test;
CREATE VIEW  v3 AS SELECT test.a, v2.c FROM test JOIN v2 ON test.b = v2.b;

 List OF relations
 Schema | Name | Type  |   Owner    | Storage 
--------+------+-------+------------+---------
 public | test | TABLE | adbpgadmin | heap
 public | v1   | VIEW  | adbpgadmin | 
 public | v2   | VIEW  | adbpgadmin | 
 public | v3   | VIEW  | adbpgadmin | 
(4 ROWS)

創(chuàng)建修改基表或視圖的函數(shù)，該函數(shù)在修改基表或視圖之前會刪除所有依賴視圖并記錄依賴視圖的DDL，修改完成后可以直接重建依賴視圖。具體函數(shù)及操作如下。

CREATE OR REPLACE FUNCTION public.record_dependency_ddl(schema_name TEXT, table_name TEXT, column_name TEXT)
RETURNS VOID AS $$
DECLARE 
    view_info RECORD;
    combine_ddl TEXT := '';
    drop_ddl TEXT := '---- DROP VIEW ---' || E'\n';
    drop_str TEXT;
    full_name TEXT;
    ddl_line TEXT;
BEGIN 
    CREATE TEMP TABLE IF NOT EXISTS temp_drop_dependency_ddl (
        ddl_statement TEXT NOT NULL
    );

    CREATE TEMP TABLE IF NOT EXISTS temp_create_dependency_ddl (
        ddl_statement TEXT NOT NULL
    );

    TRUNCATE temp_drop_dependency_ddl;
    TRUNCATE temp_create_dependency_ddl;

    IF column_name != '' THEN
        FOR view_info IN
            WITH RECURSIVE find_views AS (
            SELECT DISTINCT                               
            n.nspname AS dependent_schema,
            cl.relname AS dependent_view,
            cl.oid AS dependent_oid,
            cl.relkind AS dependent_type,
            nb.nspname AS source_schema,
            c.relname AS source_table,
            1 AS depth
            FROM
            pg_depend d
            JOIN pg_rewrite r ON d.objid = r.oid
            JOIN pg_class cl ON r.ev_class = cl.oid
            JOIN pg_class c ON d.refobjid = c.oid
            JOIN pg_attribute a ON a.attrelid = c.oid AND a.attnum = d.refobjsubid
            JOIN pg_namespace n ON cl.relnamespace = n.oid
            JOIN pg_namespace nb ON c.relnamespace = nb.oid
            WHERE
            d.deptype = 'n'
            AND d.classid='pg_rewrite'::regclass
            AND (cl.relkind = 'v' OR cl.relkind = 'm')  -- 'v' means the source object is a view
            AND nb.nspname = schema_name  -- schema of the table
            AND c.relname = table_name -- name of the table
            AND a.attname = column_name -- name of the column
            UNION ALL
            SELECT                               
            n.nspname,
            cl.relname,
            cl.oid,
            cl.relkind,
            nb.nspname,
            c.relname,
            fv.depth + 1
            FROM
            pg_depend d
            JOIN pg_rewrite r ON d.objid = r.oid
            JOIN pg_class cl ON r.ev_class = cl.oid
            JOIN pg_class c ON d.refobjid = c.oid
            JOIN pg_namespace n ON cl.relnamespace = n.oid
            JOIN pg_namespace nb ON c.relnamespace = nb.oid
            JOIN find_views fv ON fv.dependent_oid = c.oid
            WHERE
            d.deptype = 'n'
            AND d.classid='pg_rewrite'::regclass
            AND (cl.relkind = 'v' OR cl.relkind = 'm')  -- 'v' means the source object is a view
            AND cl.oid <> c.oid
            )
            
            SELECT DISTINCT depth, dependent_schema, dependent_view, dependent_type
            FROM find_views
            ORDER BY depth
        LOOP

            full_name := view_info.dependent_schema || '.' || view_info.dependent_view;
            FOR ddl_line IN
                SELECT dump_table_ddl(full_name)
            LOOP
                IF ddl_line LIKE 'CREATE MATERIALIZED VIEW%' THEN
                    ddl_line := REPLACE(ddl_line, 'VIEW', 'VIEW IF NOT EXISTS');
                ELSIF ddl_line LIKE 'CREATE VIEW%' THEN
                    ddl_line := REPLACE(ddl_line, 'CREATE VIEW', 'CREATE OR REPLACE VIEW');
                END IF;
                combine_ddl := combine_ddl || ddl_line || E'\n';
            END LOOP;
            
            IF view_info.depth = 1 THEN
                drop_str := 'DROP VIEW ';
                IF view_info.dependent_type = 'm' THEN
                    drop_str := 'DROP MATERIALIZED VIEW ';
                END IF;
                drop_ddl := drop_ddl || drop_str || 'IF EXISTS ' || full_name || ' CASCADE;' || E'\n';
            END IF;
        END LOOP;
    ELSE 
        FOR view_info IN
            WITH RECURSIVE find_views AS (
            SELECT DISTINCT                               
            n.nspname AS dependent_schema,
            cl.relname AS dependent_view,
            cl.oid AS dependent_oid,
            cl.relkind AS dependent_type,
            nb.nspname AS source_schema,
            c.relname AS source_table,
            1 AS depth
            FROM
            pg_depend d
            JOIN pg_rewrite r ON d.objid = r.oid
            JOIN pg_class cl ON r.ev_class = cl.oid
            JOIN pg_class c ON d.refobjid = c.oid
            JOIN pg_namespace n ON cl.relnamespace = n.oid
            JOIN pg_namespace nb ON c.relnamespace = nb.oid
            WHERE
            d.deptype = 'n'
            AND d.classid='pg_rewrite'::regclass
            AND (cl.relkind = 'v' OR cl.relkind = 'm')  -- 'v' means the source object is a view
            AND nb.nspname = schema_name  -- schema of the table
            AND c.relname = table_name -- name of the table
            UNION ALL
            SELECT                               
            n.nspname,
            cl.relname,
            cl.oid,
            cl.relkind,
            nb.nspname,
            c.relname,
            fv.depth + 1
            FROM
            pg_depend d
            JOIN pg_rewrite r ON d.objid = r.oid
            JOIN pg_class cl ON r.ev_class = cl.oid
            JOIN pg_class c ON d.refobjid = c.oid
            JOIN pg_namespace n ON cl.relnamespace = n.oid
            JOIN pg_namespace nb ON c.relnamespace = nb.oid
            JOIN find_views fv ON fv.dependent_oid = c.oid
            WHERE
            d.deptype = 'n'
            AND d.classid='pg_rewrite'::regclass
            AND (cl.relkind = 'v' OR cl.relkind = 'm')  -- 'v' means the source object is a view
            AND cl.oid <> c.oid
            )
            
            SELECT DISTINCT depth, dependent_schema, dependent_view, dependent_type
            FROM find_views
            ORDER BY depth
        LOOP

            full_name := view_info.dependent_schema || '.' || view_info.dependent_view;
            FOR ddl_line IN
                SELECT dump_table_ddl(full_name)
            LOOP
                IF ddl_line LIKE 'CREATE MATERIALIZED VIEW%' THEN
                    ddl_line := REPLACE(ddl_line, 'VIEW', 'VIEW IF NOT EXISTS');
                ELSIF ddl_line LIKE 'CREATE VIEW%' THEN
                    ddl_line := REPLACE(ddl_line, 'CREATE VIEW', 'CREATE OR REPLACE VIEW');
                END IF;
                combine_ddl := combine_ddl || ddl_line || E'\n';
            END LOOP;
            
            IF view_info.depth = 1 THEN
                drop_str := 'DROP VIEW ';
                IF view_info.dependent_type = 'm' THEN
                    drop_str := 'DROP MATERIALIZED VIEW ';
                END IF;
                drop_ddl := drop_ddl || drop_str || 'IF EXISTS ' || full_name || ' CASCADE;' || E'\n';
            END IF;
        END LOOP;
    END IF;
  
    INSERT INTO temp_drop_dependency_ddl VALUES (drop_ddl);
    INSERT INTO temp_create_dependency_ddl VALUES (combine_ddl);
END;
$$ LANGUAGE plpgsql;

CREATE OR REPLACE FUNCTION public.drop_dependency_table()
RETURNS VOID AS
$$
DECLARE
    ddl_text TEXT;
BEGIN
    FOR ddl_text IN SELECT ddl_statement FROM temp_drop_dependency_ddl
    LOOP
        EXECUTE ddl_text;
    END LOOP;
END;
$$
LANGUAGE plpgsql;

CREATE OR REPLACE FUNCTION public.create_dependency_table()
RETURNS VOID AS
$$
DECLARE
    ddl_text TEXT;
BEGIN
    FOR ddl_text IN SELECT ddl_statement FROM temp_create_dependency_ddl
    LOOP
        EXECUTE ddl_text;
    END LOOP;

    SET search_path TO PUBLIC;
END;
$$
LANGUAGE plpgsql;

說明

這些函數(shù)只能用于依賴視圖定義不會改變的情況下，如果需要同時修改依賴視圖，需要在導出的DDL基礎上進行手動修改與重建。

執(zhí)行record_dependency_ddl函數(shù)用于記錄依賴視圖的DROP命令信息和CREATE命令信息，這些命令分別存儲在temp_drop_dependency_ddl臨時表和temp_create_dependency_ddl臨時表中。如下所示為查詢依賴于public.test表b列的視圖。

SELECT record_dependency_ddl('public','test','b');
NOTICE:  TABLE doesn't have 'DISTRIBUTED BY' clause -- Using column named 'ddl_statement' as the Greenplum Database data distribution key for this table.
HINT:  The 'DISTRIBUTED BY' clause determines the distribution OF data. Make sure COLUMN(s) chosen ARE the optimal data distribution key TO minimize skew.
NOTICE:  TABLE doesn't have 'DISTRIBUTED BY' clause -- Using column named 'ddl_statement' as the Greenplum Database data distribution key for this table.
HINT:  The 'DISTRIBUTED BY' clause determines the distribution OF data. Make sure COLUMN(s) chosen ARE the optimal data distribution key TO minimize skew.
 record_dependency_ddl 
-----------------------
(1 row)

SELECT * FROM temp_drop_dependency_ddl ;
ddl_statement              
----------------------------------------
 ---- DROP VIEW ---                    +
 DROP VIEW IF EXISTS public.v1 CASCADE;+
 DROP VIEW IF EXISTS public.v2 CASCADE;+
 DROP VIEW IF EXISTS public.v3 CASCADE;+
 
(1 ROW)

SELECT * FROM temp_create_dependency_ddl ;
ddl_statement                        
------------------------------------------------------------
 --                                                       +
 -- Greenplum Database database dump                       +
 --                                                        +                                                     
 -- Dumped from database version 12.12                     +
 -- Dumped by pg_dump version 12.12                        +                                                     
 SET gp_default_storage_options = '';                      +
 SET statement_timeout = 0;                                +
 SET lock_timeout = 0;                                     +
 SET idle_in_transaction_session_timeout = 0;              +
 SET idle_session_timeout = 0;                             +
 SET client_encoding = 'UTF8';                             +
 SET standard_conforming_strings = on;                     +
 SELECT pg_catalog.set_config('search_path', '', false);   +
 SET check_function_bodies = false;                        +
 SET xmloption = content;                                  +
 SET client_min_messages = warning;                        +
 SET row_security = off;                                   +                                                      
 --                                                        +
 -- Name: v1; Type: VIEW; Schema: public; Owner: adbpgadmin+
 --                                                        +                                                           
 CREATE OR REPLACE VIEW public.v1 AS                       +
  SELECT test.a,                                           +
     test.b                                                +
    FROM public.test;                                      +
                                                           +                                                   
 ALTER TABLE public.v1 OWNER TO adbpgadmin;                +
                                                           +
 --                                                        +
 -- Greenplum Database database dump complete              +
 --                                                        +                                                                                                                 +
 --                                                        +
 -- Greenplum Database database dump                       +
 --                                                        +                                                        
 -- Dumped from database version 12.12                     +
 -- Dumped by pg_dump version 12.12                        +                                                       
 SET gp_default_storage_options = '';                      +
 SET statement_timeout = 0;                                +
 SET lock_timeout = 0;                                     +
 SET idle_in_transaction_session_timeout = 0;              +
 SET idle_session_timeout = 0;                             +
 SET client_encoding = 'UTF8';                             +
 SET standard_conforming_strings = on;                     +
 SELECT pg_catalog.set_config('search_path', '', false);   +
 SET check_function_bodies = false;                        +
 SET xmloption = content;                                  +
 SET client_min_messages = warning;                        +
 SET row_security = off;                                   +                                                    
 --                                                        +
 -- Name: v2; Type: VIEW; Schema: public; Owner: adbpgadmin+
 --                                                        +                                                       
 CREATE OR REPLACE VIEW public.v2 AS                       +
  SELECT test.b,                                           +
     test.c                                                +
    FROM public.test;                                      +
                                                           +                                                     
 ALTER TABLE public.v2 OWNER TO adbpgadmin;                +                                                        
 --                                                        +
 -- Greenplum Database database dump complete              +
 --                                                        +                                                                                                    +
 --                                                        +
 -- Greenplum Database database dump                       +
 --                                                        +                                                     
 -- Dumped from database version 12.12                     +
 -- Dumped by pg_dump version 12.12                        +                                                    
 SET gp_default_storage_options = '';                      +
 SET statement_timeout = 0;                                +
 SET lock_timeout = 0;                                     +
 SET idle_in_transaction_session_timeout = 0;              +
 SET idle_session_timeout = 0;                             +
 SET client_encoding = 'UTF8';                             +
 SET standard_conforming_strings = on;                     +
 SELECT pg_catalog.set_config('search_path', '', FALSE);   +
 SET check_function_bodies = FALSE;                        +
 SET xmloption = content;                                  +
 SET client_min_messages = warning;                        +
 SET row_security = off;                                   +                                                      
 --                                                        +
 -- Name: v3; Type: VIEW; Schema: public; Owner: adbpgadmin+
 --                                                        +                                                       
 CREATE OR REPLACE VIEW public.v3 AS                       +
  SELECT test.a,                                           +
     v2.c                                                  +
    FROM (public.test                                      +
      JOIN public.v2 ON ((test.b = v2.b)));                +
                                                           +                                                       
 ALTER TABLE public.v3 OWNER TO adbpgadmin;                +                                                      
 --                                                        +
 -- Greenplum Database database dump complete              +
 --                                                        +                                                                                                    +
 --                                                        +
 -- Greenplum Database database dump                       +

 -- Dumped from database version 12.12                     +
 -- Dumped by pg_dump version 12.12                        +                                                       
 SET gp_default_storage_options = '';                      +
 SET statement_timeout = 0;                                +
 SET lock_timeout = 0;                                     +
 SET idle_in_transaction_session_timeout = 0;              +
 SET idle_session_timeout = 0;                             +
 SET client_encoding = 'UTF8';                             +
 SET standard_conforming_strings = on;                     +
 SELECT pg_catalog.set_config('search_path', '', false);   +
 SET check_function_bodies = false;                        +
 SET xmloption = content;                                  +
 SET client_min_messages = warning;                        +
 SET row_security = off;                                   +                                                       
 --                                                        +
 -- Name: v3; Type: VIEW; Schema: public; Owner: adbpgadmin+
 --                                                        +                                                           
 CREATE OR REPLACE VIEW public.v3 AS                       +
  SELECT test.a,                                           +
     v2.c                                                  +
    FROM (public.test                                      +
      JOIN public.v2 ON ((test.b = v2.b)));                +
                                                           +                                                          
 ALTER TABLE public.v3 OWNER TO adbpgadmin;                +                                                        
 --                                                        +
 -- Greenplum Database database dump complete              +
 --                                                        +                                                      
 (1 ROW)

執(zhí)行drop_dependency_table函數(shù)將依賴視圖全部刪除，修改基表test的b列后，執(zhí)行create_dependency_table函數(shù)進行依賴視圖的重建。

SELECT drop_dependency_table();
NOTICE: DROP cascades TO VIEW v3
NOTICE: VIEW "v3" does NOT exist, skipping
 drop_dependency_table 
-----------------------
(1 ROW)
SELECT create_dependency_table();
 create_dependency_table 
-------------------------
(1 ROW)

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依賴視圖DDL修改最佳實踐