复制架构并在同一数据库中创建具有不同名称的新架构

Question

我有办法复制现有的架构,并在postgres的同一个数据库中生成另一个名称的新架构.

Answer 1

使用pg_dump将当前架构转储到SQL格式的文件中.打开文件,用新名称替换schemaname并在数据库中执行此脚本以创建新模式以及此模式中的所有其他对象.

Answer 2

查看此PostgreSQL 的 wiki 页面。它包含clone_schema您需要的函数，但该函数仅克隆表。该页面引用了这篇文章，其中包含一个克隆架构所需的所有内容的函数。这个函数对我来说效果很好，我设法用 JDBC API 执行它。

但是当架构名称包含-或大写字母时，我遇到了一些问题。经过研究，我发现问题的根源在于quote_ident()方法。我更改了clone_schema函数以使用任何模式名称。我在这里分享新功能，希望它会帮助某人：

-- Function: clone_schema(text, text)

-- DROP FUNCTION clone_schema(text, text);

CREATE OR REPLACE FUNCTION clone_schema(
    source_schema text,
    dest_schema text,
    include_recs boolean)
  RETURNS void AS
$BODY$

--  This function will clone all sequences, tables, data, views & functions from any existing schema to a new one
-- SAMPLE CALL:
-- SELECT clone_schema('public', 'new_schema', TRUE);

DECLARE
  src_oid          oid;
  tbl_oid          oid;
  func_oid         oid;
  object           text;
  buffer           text;
  srctbl           text;
  default_         text;
  column_          text;
  qry              text;
  dest_qry         text;
  v_def            text;
  seqval           bigint;
  sq_last_value    bigint;
  sq_max_value     bigint;
  sq_start_value   bigint;
  sq_increment_by  bigint;
  sq_min_value     bigint;
  sq_cache_value   bigint;
  sq_log_cnt       bigint;
  sq_is_called     boolean;
  sq_is_cycled     boolean;
  sq_cycled        char(10);

BEGIN

-- Check that source_schema exists
  SELECT oid INTO src_oid
    FROM pg_namespace
   WHERE nspname = source_schema;
  IF NOT FOUND
    THEN 
    RAISE EXCEPTION 'source schema % does not exist!', source_schema;
    RETURN ;
  END IF;

  -- Check that dest_schema does not yet exist
  PERFORM nspname 
    FROM pg_namespace
   WHERE nspname = dest_schema;
  IF FOUND
    THEN 
    RAISE EXCEPTION 'dest schema % already exists!', dest_schema;
    RETURN ;
  END IF;

  EXECUTE 'CREATE SCHEMA "' || dest_schema || '"';

  -- Create sequences
  -- TODO: Find a way to make this sequence's owner is the correct table.
  FOR object IN
    SELECT sequence_name::text 
      FROM information_schema.sequences
     WHERE sequence_schema = source_schema
  LOOP
    EXECUTE 'CREATE SEQUENCE "' || dest_schema || '".' || quote_ident(object);
    srctbl := '"' || source_schema || '".' || quote_ident(object);

    EXECUTE 'SELECT last_value, max_value, start_value, increment_by, min_value, cache_value, log_cnt, is_cycled, is_called 
              FROM "' || source_schema || '".' || quote_ident(object) || ';' 
              INTO sq_last_value, sq_max_value, sq_start_value, sq_increment_by, sq_min_value, sq_cache_value, sq_log_cnt, sq_is_cycled, sq_is_called ; 

    IF sq_is_cycled 
      THEN 
        sq_cycled := 'CYCLE';
    ELSE
        sq_cycled := 'NO CYCLE';
    END IF;

    EXECUTE 'ALTER SEQUENCE "'   || dest_schema || '".' || quote_ident(object) 
            || ' INCREMENT BY ' || sq_increment_by
            || ' MINVALUE '     || sq_min_value 
            || ' MAXVALUE '     || sq_max_value
            || ' START WITH '   || sq_start_value
            || ' RESTART '      || sq_min_value 
            || ' CACHE '        || sq_cache_value 
            || sq_cycled || ' ;' ;

    buffer := '"' || dest_schema || '".' || quote_ident(object);
    IF include_recs 
        THEN
            EXECUTE 'SELECT setval( ''' || buffer || ''', ' || sq_last_value || ', ' || sq_is_called || ');' ; 
    ELSE
            EXECUTE 'SELECT setval( ''' || buffer || ''', ' || sq_start_value || ', ' || sq_is_called || ');' ;
    END IF;

  END LOOP;

-- Create tables 
  FOR object IN
    SELECT TABLE_NAME::text 
      FROM information_schema.tables 
     WHERE table_schema = source_schema
       AND table_type = 'BASE TABLE'

  LOOP
    buffer := '"' || dest_schema || '".' || quote_ident(object);
    EXECUTE 'CREATE TABLE ' || buffer || ' (LIKE "' || source_schema || '".' || quote_ident(object) 
        || ' INCLUDING ALL)';

    IF include_recs 
      THEN 
      -- Insert records from source table
      EXECUTE 'INSERT INTO ' || buffer || ' SELECT * FROM "' || source_schema || '".' || quote_ident(object) || ';';
    END IF;

    FOR column_, default_ IN
      SELECT column_name::text, 
             REPLACE(column_default::text, source_schema, dest_schema) 
        FROM information_schema.COLUMNS 
       WHERE table_schema = dest_schema 
         AND TABLE_NAME = object 
         AND column_default LIKE 'nextval(%"' || source_schema || '"%::regclass)'
    LOOP
      EXECUTE 'ALTER TABLE ' || buffer || ' ALTER COLUMN ' || column_ || ' SET DEFAULT ' || default_;
    END LOOP;

  END LOOP;

--  add FK constraint
  FOR qry IN
    SELECT 'ALTER TABLE "' || dest_schema || '".' || quote_ident(rn.relname) 
                          || ' ADD CONSTRAINT ' || quote_ident(ct.conname) || ' ' || pg_get_constraintdef(ct.oid) || ';'
      FROM pg_constraint ct
      JOIN pg_class rn ON rn.oid = ct.conrelid
     WHERE connamespace = src_oid
       AND rn.relkind = 'r'
       AND ct.contype = 'f'

    LOOP
      EXECUTE qry;

    END LOOP;


-- Create views 
  FOR object IN
    SELECT table_name::text,
           view_definition 
      FROM information_schema.views
     WHERE table_schema = source_schema

  LOOP
    buffer := '"' || dest_schema || '".' || quote_ident(object);
    SELECT view_definition INTO v_def
      FROM information_schema.views
     WHERE table_schema = source_schema
       AND table_name = quote_ident(object);

    EXECUTE 'CREATE OR REPLACE VIEW ' || buffer || ' AS ' || v_def || ';' ;

  END LOOP;

-- Create functions 
  FOR func_oid IN
    SELECT oid
      FROM pg_proc 
     WHERE pronamespace = src_oid

  LOOP      
    SELECT pg_get_functiondef(func_oid) INTO qry;
    SELECT replace(qry, source_schema, dest_schema) INTO dest_qry;
    EXECUTE dest_qry;

  END LOOP;

  RETURN; 

END;

$BODY$
  LANGUAGE plpgsql VOLATILE
  COST 100;
ALTER FUNCTION clone_schema(text, text, boolean)
  OWNER TO postgres;

Answer 3

• 如果复制模式意味着复制数据库，那么只需使用TEMPLATE选项来创建副本：CREATE DATABASE dbname_target TEMPLATE dbname_source;

这也会复制数据。因此，如果您需要许多副本，您可能需要创建自己的模板。请参阅模板数据库。

• 如果您只需要架构，那么我建议您将 DB DDL 脚本置于源代码控制之下（无论如何这是一个好主意），并使用一个单独的（模板化）脚本来为您创建架构。基本上，您有一个 SQL 文件，您可以在其中将 a 替换${schema_name}为新的架构名称，然后在数据库上执行此脚本。通过这种方式，如果您对此进行更改schema，您还可以使用脚本将架构更新到新版本，在这种情况下，您必须为每个用户架构执行此操作。