数据库上云实践：使用Ora2pg进行数据库迁移
目录
概述
本文将介绍如何使用 Oracle到postgresql的迁移使用ora2pg工具。配置环境后，你将了解如何编写配置文件，进行数据库迁移任务。
重要
- 在本教程中，你将了解如何执行以下操作：
- 编写ora2pg配置文件
- 通过配置文件将Oracle中的表、序列、视图、同义词、函数过程包进行迁移
前置条件
- perl解释器
- perl 模块 DBD(DataBase Description) *DBI(DataBase Interface)
- ora2pg源码
配置环境
Win环境配置
- perl解释器安装: strawberry-perl-5.32.1.1-64bit.msi
- 在win下 strawberry-perl(version 5.32以后)自带
DBD::Oracle和DBD::Pg.
perl -MCPAN -e install DBD::Oracle
perl -MCPAN -e install DBD::Pg
- 利用perl解释器，解释makefile.pl文件，配置环境并安装ora2pg。win下使用gmake指令
cd ora2pg
perl Makefile.PL
gmake && gmake install
- DBI的安装需要下载源码包，通过源码安装(在win下，可以使用gmake指令)
tar -zxvf DBI-1.641.tar.gz
cd DBI-1.641
perl Makefile.PL
gmake && gmake install
- 安装Oracle客户端
linux环境配置
-
perl版本5.10以上，安装依赖包
perl-ExtUtils-CBuilderperl-ExtUtils-MakeMaker(注：win下的strawberry-perl自带这两个包)yum install -y perl perl-ExtUtils-CBuilder perl-ExtUtils-MakeMaker -
安装DBI
tar -zxvf DBI-1.641.tar.gz cd DBI-1.641 perl Makefile.PL make && make install -
安装Oracle客户端(略)
rpm -ivh oracle-instantclient12.2-basic-12.2.0.1.0-1.x86_64.rpm rpm -ivh oracle-instantclient12.2-devel-12.2.0.1.0-1.x86_64.rpm rpm -ivh oracle-instantclient12.2-jdbc-12.2.0.1.0-1.x86_64.rpm rpm -ivh oracle-instantclient12.2-sqlplus-12.2.0.1.0-1.x86_64.rpm -
安装DBD-Oracle
定义ORACLE_HOME环境变量
tar -zxvf DBD-Oracle-1.74.tar.gz cd DBD-Oracle-1.74 perl Makefile.PL make && make install -
安装DBD:PG
#使用官方提供的yum安装方式 #Linux系统版本centos7 64位版本 #Pg版本为12 yum install -y https://download.postgresql.org/pub/repos/yum/reporpms/EL-7-x86_64/pgdg-redhat-repo-latest.noarch.rpm yum install postgresql12 yum install postgresql12-server yum install postgresql12-contrib #配置开机启动与启动 systemctl enable postgresql-12 systemctl start postgresql-12 #修改配置文件 #打开并编辑文件“/var/lib/pgsql/12/data/postgresql.conf”。将“#listen_addresses = ‘localhost’”改为“listen_addresses = ‘*’” #打开并编辑文件“/var/lib/pgsql/12/data/pg_hba.conf”。在文件的末尾添加“host all all 0.0.0.0/0 md5” #设置pgsql的环境变量 -
安装Ora2PG
tar -zxvf ora2pg-22.1.tar.bz2cd ora2pg-22.1/perl Makefile.PLmake && make install
Ora2Pg使用方法
编写conf文件，执行指令将Oracle转化为Postgresql
ora2pg -c ora2pg_table.conf
配置文件ora2pg_table.conf
PG_VERSION 12
ORACLE_HOME /home/oracle/app/oracle/product/11.2.0/dbhome_1
ORACLE_DSN dbi:Oracle:host=xx.xx.x.xxx;service_name=xxx;port=xx
ORACLE_USER xxxxxx
ORACLE_PWD ######
USER_GRANTS 1
SCHEMA xxxx
TYPE TABLE
PG_NUMERIC_TYPE 0
PG_INTEGER_TYPE 1
DEFAULT_NUMERIC float
#SKIP fkeys pkeys ukeys indexes checks
NLS_LANG AMERICAN_AMERICA.UTF8
OUTPUT /home/ora2pg/xxxxx.sql
配置文件解释：Oracle数据库连接配置项
ORACLE_HOME
使用ORACLE_HOME作为环境变量，ora2pg可以通过该参数找到Perl的DBD模块连接ORACLE数据库所需要的依赖包。
- 若在Linux环境下，该变量可能为：
/home/oracle/app/oracle/product/11.2.0/dbhome_1 - 若在Windows环境下，该变量可能为：
D:\app\Administrator\product\11.2.0\dbhome_1
ORACLE_DSN
该参数与Oracle数据库具体配置有关，主要为数据库的
host,sid,port等参数
dbi:Oracle:host=oradb_host.myhost.com;sid=DB_SID;port=1521dbi:Oracle:DB_SID
#On 18c this could be for example:dbi:Oracle:host=192.168.1.29;service_name=pdb1;port=1521
#for the second notation the SID should be declared in the well known
#file $ORACLE_HOME/network/admin/tnsnames.ora or in the path given to#the TNS_ADMIN environment variable.
#For MySQL the DSN will lool like this:dbi:mysql:host=192.168.1.10;database=sakila;port=3306
the 'sid' part is replaced by 'database'.
ORACLE_USER et ORACLE_PWD
USER和PWD表示Oracle数据库的用户名和密码，选用账号的时候尽量选择DBA权限的账号，以防止数据库扫描时出现的权限问题。
- 若配置文件*.conf未设置该参数，可安装perl的Term::ReadKey模块，在执行指令时的交互式命令行输入账号密码
- 连接本地的数据据库实例如果为"as sysdba"，那么可以将ORACLE_USER设置为""，密码为空
USER_GRANTS
- 如果连接Oracle数据库为普通，该值设置为1，此时没有权限抽取DBA 表格，此时将会使用ALL 表格
- 若导出类型为
GRANT，该值必须设置为0，否者将无效。
TRANSACTION*
事务隔离类型，如果需要改变导出数据的默认隔离级别，需要设置该参数，总共由4中事务隔离类型：
- READ ONLY
- READ WRITE
- ISOLATION LEVEL SERIALIZABLE
- ISOLATION LEVEL READ COMMITTED
基本原理
在Oarcle数据库和Postgresql数据库中间，使用一台机器，这台机器实现将Oracle数据库的元数据导出，并根据数据库中的表格、序列、视图等内容生成符合Postgresql语法的DDL(data definition language)，并保存为相应的 *.sql文件按
数据类型变化(参考Ora2PG源码定义)
our %TYPE = ( 'NUMBER' => 'numeric',
# CHAR types limit of 2000 bytes with defaults to 1 if no length
# is specified. PG char type has max length set to 8104 so it
# should match all needs
'CHAR' => 'char',
'NCHAR' => 'char',
# VARCHAR types the limit is 2000 bytes in Oracle 7 and 4000 in
# Oracle 8. PG varchar type has max length iset to 8104 so it
# should match all needs
'VARCHAR' => 'varchar',
'NVARCHAR' => 'varchar',
'VARCHAR2' => 'varchar',
'NVARCHAR2' => 'varchar',
'STRING' => 'varchar',
# The DATE data type is used to store the date and time
# information. PG type timestamp should match all needs.
'DATE' => 'timestamp',
# Type LONG is like VARCHAR2 but with up to 2Gb. PG type text
# should match all needs or if you want you could use blob
'LONG' => 'text',
# Character data of variable length
'LONG RAW' => 'bytea',
# Types LOB and FILE are like LONG but with up to 4Gb. PG type
# text should match all needs or if you want you could use blob
# (large object)
'CLOB' => 'text',
# A large object containing single-byte characters
'NCLOB' => 'text',
# A large object containing national character set data
'BLOB' => 'bytea',
# Binary large object
# The full path to the external file is returned if destination type is text.
# If the destination type is bytea the content of the external file is returned.
'BFILE' => 'bytea',
# Locator for external large binary file
# The RAW type is presented as hexadecimal characters. The
# contents are treated as binary data. Limit of 2000 bytes
# PG type text should match all needs or if you want you could
# use blob (large object)、
'RAW' => 'bytea',
'ROWID' => 'oid',
'UROWID' => 'oid',
'FLOAT' => 'double precision',
'DEC' => 'decimal',
'DECIMAL' => 'decimal',
'DOUBLE PRECISION' => 'double precision',
'INT' => 'numeric',
'INTEGER' => 'numeric',
'BINARY_INTEGER' => 'integer',
'PLS_INTEGER' => 'integer',
'REAL' => 'real',
'SMALLINT' => 'smallint',
'BINARY_FLOAT' => 'double precision',
'BINARY_DOUBLE' => 'double precision',
'TIMESTAMP' => 'timestamp',
'BOOLEAN' => 'boolean',
'INTERVAL' => 'interval',
'XMLTYPE' => 'xml',
'TIMESTAMP WITH TIME ZONE' => 'timestamp with time zone',
'TIMESTAMP WITH LOCAL TIME ZONE' => 'timestamp with time zone',
'SDO_GEOMETRY' => 'geometry'
);
常见的Oracle对象到Postgresql数据库的转换
| ORACLE | POSTGRESQL |
|---|---|
| Database Link | Foreign Data Wrapper |
| External Table | Foreign Table |
| Synonym | View / Set search_path |
| Global Temporary Table | Unlogged Table / Temp Table |
| Virtual column | View / Function / Trigger |
| Connect by | With Recursive |
| Reverse Index | Functional Index |
| Index Organized Table (IOT table) | Cluster the table according to an Index |
数据库链接(Database Link)
Oracle
CREATE PUBLIC DATABASE LINK remote_service USING 'remote_db';
SELECT * FROM employees@remote_service;
Postgresql
CREATE SERVER remote_service FOREIGN DATA WRAPPER oracle_fdw OPTIONS (dbserver 'remote_db');
CREATE USER MAPPING FOR current_user SERVER remote_service OPTIONS (user 'scott', password 'tiger');
CREATE FOREIGN TABLE employees_fdw (<columns_list>) SERVER remote_service OPTIONS(schema 'HR',table 'EMPLOYEES');
外部表(External Tables)
假设有这么一张表
cat /data/ext/file_ext.csv
1234,ALBERT,GRANT,21
1235,ALFRED,BLUEOS,26
1236,BERNY,JOLYSE,34
Oracle
CREATE OR REPLACE DIRECTORY ext_dir AS '/data/ext/';
CREATE TABLE ext_table (
empno VARCHAR2(4),
firstname VARCHAR2(20),
lastname VARCHAR2(20),
age VARCHAR2(2)
) ORGANIZATION EXTERNAL (DEFAULT DIRECTORY ext_dir ACCESS PARAMETERS (…LOCATION ('file_ext.csv')));
Postgresql
CREATE FOREIGN TABLE ext_table(
empno VARCHAR(4),
firstname VARCHAR(20),
lastname VARCHAR(20),
age VARCHAR(2)
)SERVER ext_dir OPTIONS (filename '/data/ext/file_ext.csv', format 'csv', delimiter ',');
同义词(Synonyms)
Synonyms are not supported in PostgreSQL
Oracle
CREATE PUBLIC SYNONYM emp_table FOR hr.employees [@ dblink];
Postgresql
有两种方式search path和view
--search path – session level – no permanent effect, it needs to be set for every connectionSET search_path TO other_schema;
--search path – role or database level – it takes permanent effect--@postgresqlalter database <database_name> set search_path = "other_schema";--@database_namealter role <role_name> set search_path = "other_schema";--view:CREATE VIEW public.emp_table AS SELECT * FROM hr.employees;ALTER VIEW public.emp_table OWNER TO hr;GRANT ALL ON public.emp_table TO PUBLIC;
全局临时表(Global Temporary Tables)
Option 1: Unlogged Table:
Oracle
CREATE GLOBAL TEMPORARY TABLE MY_CONTRACT_MONTH(
ID NUMBER(10),
CMONTH DATE
)ON COMMIT DELETE ROWS;
PostgreSQL
CREATE UNLOGGED TABLE MY_CONTRACT_MONTH(
ID number,
CMONTH timestamp,
pid bigint default pg_backend_pid()
);
ALTER TABLE MY_CONTRACT_MONTH ENABLE ROW LEVEL SECURITY;
ALTER TABLE MY_CONTRACT_MONTH FORCE ROW LEVEL SECURITY;
CREATE POLICY cm_pid ON MY_CONTRACT_MONTH TO <role_name>
USING (pid = (selectpg_backend_pid()));
在Postgresql中Role即User，若表格不保存日志，对于 Unlogged 表，必须实现行级安全，以防止会话查询其他会话数据。还需要实施一项作业，以消除非活动会话的未记录表上的数据
DELETE FROM smdr.contract_months cm
WHERE not exists (select 1 from pg_stat_activity psa where psa.pid = cm.pid);
Option 2: Temp Table:
Oracle
CREATE GLOBAL TEMPORARY TABLE MY_CONTRACT_MONTH(
ID NUMBER(10),
CMONTH DATE
)ON COMMIT DELETE ROWS;
--Oracle 永久存储临时表的定义，就像常规表的定义一样。
PostgreSQL
CREATE GLOBAL TEMPORARY TABLE MY_CONTRACT_MONTH(
ID NUMERIC,
CMONTH TIMESTAMP
)ON COMMIT DELETE ROWS;
CREATE TEMPORARY TABLE 语句创建一个临时表，该表在会话或当前事务结束时自动删除（ON COMMIT DROP 选项。在转换过程中，您需要从应用程序代码中提取 CREATE TEMPORARY TABLE 语句，存储过程、触发器等并执行它们一次以创建临时表定义。Oracle 不支持 ON COMMIT DROP，因此如果需要此选项，则需要明确每次提交后执行 DROP TABLE 语句 ON COMMIT PRESERVE ROWS 是 PostgreSQL 中的默认值，ON COMMIT DELETE ROWS 是 Oracle 中的默认值
Virtual Column
Oracle
CREATE TABLE VIRT_COL_TABLE (
id NUMBER,
first_name VARCHAR2(10),
last_name VARCHAR2(10),
salary NUMBER(9,2),
comm1 NUMBER(3),
comm2 NUMBER(3),
salary1 AS (ROUND(salary*(1+comm1/100),2)),
salary2 NUMBER GENERATED ALWAYS AS (ROUND(salary*(1+comm2/100),2)) VIRTUAL
);
PostgreSQL
CREATE TABLE virt_col_table (
id bigint NOT NULL,
first_name varchar(10),
last_name varchar(10),
salary double precision,
comm1 smallint,
comm2 smallint,
salary1 bigint,
salary2 bigint);
Ora2pg通过一个包含触发器的定义的额外文件 VIRTUAL_COLUMNS_(...).sql，来实现原始Virtual Column的默认值
DROP TRIGGER IF EXISTS virt_col_VIRT_COL_TABLE_trigger ON VIRT_COL_TABLE CASCADE;
CREATE OR REPLACE FUNCTION fct_virt_col_VIRT_COL_TABLE_trigger()
RETURNS trigger
AS $BODY$
BEGINNEW.SALARY2 = ROUND(NEW.SALARY*(1+NEW.COMM2/100),2);
NEW.SALARY1 = ROUND(NEW.SALARY*(1+NEW.COMM1/100),2);
RETURN NEW;
end
$BODY$ LANGUAGE 'plpgsql' SECURITY DEFINER;
CREATE TRIGGER virt_col_VIRT_COL_TABLE_trigger
BEFORE INSERT OR UPDATE ON VIRT_COL_TABLE FOR EACH ROWEXECUTE PROCEDURE fct_virt_col_VIRT_COL_TABLE_trigger();
Connect By – Hierarchical query
在Oracle通过connect by (子句) 以实现层级遍历，而在PostgreSQL中使用WITH RECURSIVE (子句)
Oracle
CREATE TABLE taxonomy (
key NUMBER(11) NOT NULL CONSTRAINT taxPkey PRIMARY KEY,
value VARCHAR2(255),taxHier NUMBER(11)
);
ALTER TABLE taxonomy ADD CONSTRAINT taxTaxFkey FOREIGN KEY (taxHier) REFERENCEStax(key);
SELECT value FROM taxonomy CONNECT BY PRIOR key = taxHier START WITH key = 0;
PostgreSQL
WITH RECURSIVE cte AS (
SELECT key, value, 1 AS level
FROM taxonomy
WHERE key = 0
UNION ALL
SELECT t.key, t.value, c.level + 1
FROM cte c
JOIN taxonomy t ON t.taxHier = c.key
)
SELECT value FROM cte ORDER BY level;
反向索引(Reverse Index)
当反向索引应用于 TEXT 列时，此解决方法有效。
Oracle
CREATE TABLE REV_TEMP (
Id NUMBER(10) NOT NULL PRIMARY KEY,
Description VARCHAR2(512) NOT NULL
);
CREATE INDEX REV_TEMP_N1 ON REV_TEMP(Description) REVERSE;
PostgreSQL
CREATE TABLE REV_TEMP (
Id NUMERIC(10) NOT NULL PRIMARY KEY,
Description VARCHAR(512) NOT NULL
);
CREATE INDEX REV_TEMP_N1 ON REV_TEMP(REVERSE(Description));
索引组织表(Index Organized Table)
Oracle 数据库默认使用堆表。 可以使用 ORGANIZATION INDEX 子句创建索引组织表，Oracle 数据库始终使用主键作为集群键。
Oracle
CREATE TABLE IOT_TEMP (
Id NUMBER(10) NOT NULL PRIMARY KEY,
Description VARCHAR2(512) NOT NULL
) ORGANIZATION INDEX;
PostgreSQL
PostgreSQL 只使用堆表。 但是，使用 CLUSTER 子句将堆表的内容与索引对齐。
CREATE TABLE IOT_TEMP (
Id NUMERIC(10) NOT NULL PRIMARY KEY,
Description VARCHAR(512) NOT NULL
);
CREATE INDEX IOT_TEMP_N1 ON IOT_TEMP(ID);
job梳理与改造
SELECT JOB,WHAT,INTERVAL,SCHEMA_USER FROM ALL_JOBS WHERE SCHEMA_USER='SJCK'
Known Unsupported
- Type inheritance and type with member method are not supported
- Global indexes over partitions are not supported
- Compound triggers are not supported
