elasticsearch bulk

情景介绍

公司2000W的数据从mysql 迁移至elasticsearch,以提供微服务。本文基于elasticsearch-py bulk操作实现数据迁移。相比于elasticsearch-dump,自由度更大，并能够进行数据处理。

API 原理

让我们先来看一下官方文档给出的栗子

POST _bulk
{ "index" : { "_index" : "test", "_id" : "1" } }
{ "field1" : "value1" }
{ "delete" : { "_index" : "test", "_id" : "2" } }
{ "create" : { "_index" : "test", "_id" : "3" } }
{ "field1" : "value3" }
{ "update" : {"_id" : "1", "_index" : "test"} }
{ "doc" : {"field2" : "value2"} }

我们可以通过kibana试验一下

elasticsearch-py

elasticsearch-py 官方文档

这里实际上我使用的是es-py的接口,栗子如下

def gendata():
    mywords = ['foo', 'bar', 'baz']
    for word in mywords:
        yield {
            "_index": "mywords",
            "_type": "document",
            "doc": {"word": word}, # field1: "value1"
        }

bulk(es, gendata())

实际操作

涉及到数据读取，以及批量的大小。一般建议是1000-5000个文档，如果你的文档很大，可以适当减少队列，大小建议是5-15MB，默认不能超过100M

import re

from elasticsearch import Elasticsearch
from elasticsearch import helpers
import pymysql

es = Elasticsearch()
conn = pymysql.connect('127.0.0.1',"root","root","literature",charset='utf8')

def read(conn,tableName):
    cursor = conn.cursor()
    sql = "show columns from {};".format(tableName)
    cursor.execute(sql)
    columns = [i[0] for i in cursor.fetchall()]

    select = "select * from {};".format(tableName)
    nums = cursor.execute(select)
    for i in range(nums):
        yield {k:v for k,v in zip(columns,cursor.fetchone())}

def bulk_insert(d):
    actions = []
    for i in d:
        _id = i.get('id')
        # 数据处理逻辑
        i['autor'] = i.get('autor').split(',')
        i['artkeyword'] = re.sub(r'[\[\]\d]',"",str(i.get('artkeyword',""))).strip(';').split(';')
        i['dateofpublication'] = i.get('dateofpublication').strftime('%Y-%m-%d') # 注意需要将datetime格式转换成字符串类型
        i['dateofsummery'] = i.get('dateofsummery').strftime('%Y-%m-%d %H:%M:%S') # 注意需要将datetime格式转换成字符串类型
        #
        action = {
            "_index":"literature",
            "_type":"_doc",
            "_id":_id,
            }
        action.update(i)
        actions.append(action)
        if len(actions) == 500:
            helpers.bulk(es,actions)
            actions = []
    if (len(actions) > 0):
        helpers.bulk(es, actions)

if __name__ == "__main__":
    d = read(conn,"literature_info")
    bulk_insert(d)
    conn.close()