2018-8-25未命名文件

2018-8-25未命名文件

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type(None) 16:35:39
elasticSearch解決大數據量字段模糊查詢，創建數據索引庫，全文檢索方式查詢。
全文檢索：檢索文本中的每一個詞與搜索項進行對此。
全文索引：採用分詞器，對文本每一個詞進行切分，創建詞條，方便進行查找。

Lucene 就是一套 全文檢索編程API ， 基於Lucene 對數據創建索引，進行查詢
如今企業開發中，更經常使用是的 solr 搜索服務器和 ElasticSearch 搜索服務器
1.索引對象： 存儲數據的表結構 ，任何搜索數據，存放在索引對象上
2.映射：數據如何存放到索引對象上，須要有一個映射配置， 數據類型、是否存儲、是否分詞
3.文檔： 一條數據記錄， 存在索引對象上
4.文檔類型： 一個索引對象 存放多種類型數據，數據用文檔類型進行標識

ElasticSearch有什麼優勢呢?
1 分佈式實時文件存儲，可將每個字段存入索引，使其能夠被檢索到。?
2 實時分析的分佈式搜索引擎。?
分佈式：索引分拆成多個分片，每一個分片可有零個或多個副本。集羣中的每一個數據節點均可承載一個或多個分片，而且協調和處理各類操做；?
負載再平衡和路由在大多數狀況下自動完成。?
3 能夠擴展到上百臺服務器，處理PB級別的結構化或非結構化數據。也能夠運行在單臺PC上（已測試）?
支持插件機制，分詞插件、同步插件、Hadoop插件、可視化插件等。

select * from students where name != "周杰倫";

select * from students where is_delete=0;

select * from students where id > 3 and gender = 0;

select * from student where name like "黃%";

select * from students where id between 3 and 8;

select * from students where height is null;

select * from students order by id desc;

select * from students where gender=1 order by id asc;

select * from students order by height desc, id asc;

select count(*) from students;

sel

select max(height) from students;

select sum(age) from students;

select avg(age) from students;

select sum(age) from students where gender = 1;

select avg(age) from students where gender = 1;

select sum(age)/count(*) from students;

select sum(age)/count(*) from students where gender = 1;

select gender from students group by gender;

select gender,group_concat(name) from students group by gender;

select gender,group_concat(name) from students group by gender;

select gender,avg(age) from students group by gender;

select gender,count(*) from students group by gender;

select gender,count() from students group by gender having count() > 2;

select gender,count(*) from students group by gender having gender = "男";

select gender,count(*) from students group by gender with rollup;

select gender,count(*),sum(age) from students group by gender with rollup;

select gender,group_concat(age) from students group by gender with rollup;

select * from students limit 0,4;

select * from students limit 2,2;

select * from students inner join classes on students.cls_id = classes.id;

select * from students inner join classes on students.cls_id = classes.id;

select * from students as s inner join classes as c on s.cls_id = c.id;

select * from students as s left join classes as c on s.cls_id = c.id;

select * from students as s right join classes c on s.cls_id = c.id;

select * from students order by id desc limt 0,2;

select * from students where age > (select avg(age) from students) ;

select * from students where age > (select avg(age) from students);

select * from classes where id in (select cls_id from students);

select * from students where (age,height) = (select max(age),max(height) from students);

select distinct gender from students;

select gender ,count(*) from students group by gender;

select gender,group_concat(name) from students group by gender;

select cls_id,group_concat(name) from students group by cls_id;

select * from students order by id desc;

select gender,count() from students group by gender having count() >2;

select gender,count(*) from students group by gender with rollup;

select * from students order by id desc limit 0,10;

select * from students inner join classes on students.cls_id = classes.id;

select students.name,classes.name from students inner join classes on students.cls_id = classes.id;

select students.name as a,classes.name as b from students inner join classes on students.cls_id = classes.id;

select * from students as s left join classes as c on s.cls_id = c.id;

select * from students as s right join classes as c on s.cls_id = c.id;

create table booktest_areainfo(
aid int primary key,
atitle varchar(20),
pid int
);

select count(*) from booktest_areainfo where pid is null;

select atitle from booktest_areainfo where pid is null;

select city.* from booktest_areainfo as city inner join booktest_areainfo as province on city.pid = province.aid where province.atitle="湖北省";

數據庫商品類表格的設計開發，

1,Django_Contab實現網站首頁靜態化頁面的定時更新； 2,Redis數據庫緩存高頻數據，加快網站的響應速度； 3，帳號（用戶名，電話號） + 密碼模式實現切換登陸，QQ，微信，微博等第三方登陸方式的引入，實現用戶多渠道登陸實現； 4,Celery搭配Admin站點類實現詳情頁面的後臺數據變更實時同步更新詳情靜態化頁面； 5,基於Cookie和Redis對傳統購物車的優化，未登陸用戶購物車數據暫存Cookies，登陸後同步數據到Redis中，提升用戶購物體驗； 6，訂單模塊的開發，Django中的Atomic來控制訂單模塊數據庫事務的執行，樂觀鎖防止高併發下的超賣現象； 7，Docker來部署FastDFS,重載Django原生的文件管理類，將FastDFS融入到項目中，實現海量文件的存儲； 8，sql數據庫雙機熱備,主從配置實現讀寫分離，提升數據庫性能； 9，Celery開啓進程訂閱redis數據過時信號，並相應的操做數據庫進行庫存的增長； 10，X-admin來搭建後臺站點管理，實現用戶權限管理；