將數據從MySQL數據庫移植到PostgreSQL

Question

我需要在運行在PostgreSQL上的數據倉庫中創建一個臨時表 ，並從使用MySQL數據庫的Magento網站導入數據，我正在嘗試使用Python。

我創建了以下查詢用於導入，

1.請檢查並確認是否可以嗎？ 還是有其他替代方法可以做到這一點？

2.另外，我想知道在移植時如何處理DATATYPE不匹配問題？

3.像multicorn這樣的外來數據說唱歌手（FDW）有什么可以做的？我們該怎么做？我只需要從源中提取幾列（源中有50列以上，我只需要15列）即可轉移到目的地，所以FDW可以工作嗎？

如果有人可以發布示例或編輯以下代碼，則將有很大幫助。

import psycopg2
import os
import time
import MySQLdb
import sys
import mysql.connector
from pprint import pprint
from datetime import datetime
from psycopg2 import sql
#from utils.utils import get_global_config


def psql_command(msql, psql, msql_command, psql_command):

    msql.execute(msql_command)

    for row in cur_msql:
        try:
            psql.execute(command, row)
        except psycopg2.Error as e:
            print "Cannot execute the query!!", e.pgerror
            sys.exit("Some problem occured with the query!!!")


def dB_Fetch():

try:
  cnx_msql = mysql.connector.connect( host=host_mysql, 
  user=user_mysql,passwd=pswd_mysql, db=dbna_mysql )

except mysql.connector.Error as e:
  print "MYSQL: Unable to connect!", e.msg
  sys.exit(1)

# Postgresql connection
try:
  cnx_psql = psycopg2.connect(conn_string_psql)
except psycopg2.Error as e:
  print('PSQL: Unable to connect!\n{0}').format(e)
  sys.exit(1)

# Cursors initializations
cur_msql = cnx_msql.cursor(dictionary=True)
cur_psql = cnx_psql.cursor()

try:
  SQL_create_Staging_schema="""CREATE SCHEMA IF NOT EXISTS staging 
  AUTHORIZATION postgres;"""

  SQL_create_sales_flat_quote="""CREATE TABLE IF NOT EXISTS 
  staging.sales_flat_quote
        (
              entity_id           BIGINT
    , store_id        BIGINT
    , customer_email      TEXT
    , customer_firstname  TEXT
    , customer_middlename TEXT
    , customer_lastname   TEXT
    , customer_is_guest   BIGINT
    , customer_group_id   BIGINT
    , created_at          TIMESTAMP WITHOUT TIME ZONE
    , updated_at          TIMESTAMP WITHOUT TIME ZONE
    , is_active             BIGINT
    , items_count           BIGINT
    , items_qty             BIGINT
    , base_currency_code            TEXT
    , grand_total           NUMERIC(12,4)
    , base_to_global_rate           NUMERIC(12,4)
    , base_subtotal         NUMERIC(12,4)
    , base_subtotal_with_discount   NUMERIC(12,4)
    );"""

SQL_create_sales_flat_quote_item="""CREATE TABLE IF NOT EXISTS 
staging.sales_flat_quote_item
        (     store_id        INTEGER
    , row_total       NUMERIC
    , updated_at      TIMESTAMP WITHOUT TIME ZONE
    , qty             NUMERIC
    , sku             CHARACTER VARYING
    , free_shipping   INTEGER
    , quote_id        INTEGER
    , price       NUMERIC
    , no_discount     INTEGER
    , item_id     INTEGER
    , product_type    CHARACTER VARYING
    , base_tax_amount NUMERIC
    , product_id      INTEGER
    , name        CHARACTER VARYING
    , created_at      TIMESTAMP WITHOUT TIME ZONE
    );"""

print("Creating  Schema")   
cur_psql.execute(SQL_create_Staging_schema)
print("schema  succesfully created")

print("Creating staging.sales_flat_quote table")
cur_psql.execute(SQL_create_sales_flat_quote)
print("staging.sales_flat_quote table  succesfully created")

print("Creating staging.sales_flat_quote_item table")
cur_psql.execute(SQL_create_sales_flat_quote_item)
print("staging.sales_flat_quote_item table  succesfully created")

cur_psql.commit();
print("Fetching data from source server")




    commands = [
(
"SELECT customer_id,entity_id,store_id,created_at,updated_at
,items_count,base_row_total,row_total,base_discount_amount
,base_subtotal_with_discount,base_to_global_rate
,is_active from sales_flat_quote 
where is_active=1;",

 "INSERT INTO staging.sales_flat_quote 
 (customer_id,entity_id,store_id,created_at,updated_at
,items_count,base_row_total,row_total,base_discount_amount
,base_subtotal_with_discount,base_to_global_rate,is_active) \
 VALUES (%(customer_id)s, %(entity_id)s
, %(store_id)s, %(created_at)s, %(updated_at)s
, %(items_count)s, %(base_row_total)s
, %(row_total)s, %(base_discount_amount)s
, %(base_subtotal_with_discount)s
, %(base_to_global_rate)s, %(is_active)s)"

),

(
 "SELECT store_id,row_total,updated_at,qty,sku
,free_shipping,quote_id,price,no_discount,item_id,product_type
,base_tax_amount,product_id,name,created_at from 
 sales_flat_quote_item",

 "INSERT INTO staging.sales_flat_quote_item 
 (store_id,row_total,updated_at,qty,sku,free_shipping
 ,quote_id,price,no_discount,item_id,product_type
 ,base_tax_amount,product_id,name,created_at) 
VALUES (%(store_id)s, %(row_total)s, %(updated_at)s
, %(qty)s, %(sku)s, %(free_shipping)s, %(quote_id)s
, %(price)s, %(no_discount)s, %(item_id)s
, %(product_type)s, %(base_tax_amount)s, %(product_id)s
, %(name)s, % . (created_at)s)"
)

                ]

for msql_command, psql_command in commands:
    psql_command(cur_msql, cur_psql, msql_command, psql_command)

 except (Exception, psycopg2.Error) as error:
     print ("Error while fetching data from PostgreSQL", error)
 finally:
     ## Closing cursors
     cur_msql.close()
     cur_psql.close()
     ## Committing
     cnx_psql.commit()
     ## Closing database connections
     cnx_msql.close()
     cnx_psql.close()


if __name__ == '__main__':
   dB_Fetch()

Answer 1

完成后，他發表了Jaisus的評論。

感謝您的評論，我認為最簡單的確實是使用FDW來完成此特定任務。 您可以在github（github.com/EnterpriseDB/mysql_fdw）上找到mysql_fdw。 您具體需要什么，您在此問題上的困難是什么？ – 5月9日12:26在Jaisus