数据库结构和索引的是否合理在很大程度上影响了数据库的性能,但是随着数据库信息负载的增大,对数据库的性能也发生了很大的影响.可能我们的数据库在一开始有着很高的性能,但是随着数据存储量的急速增长—例如订单数据—数据的性能也受到了极大的影响,一个很明显的结果就是查询的反应会非常慢.在这个时候,除了你可以优化索引及查询外,你还可以做什么?建立分区表(Table Partition)可以在某些场合下提高数据库的性能,在SQL Server 2005中也可以通过SQL语句来创建表分区,但在SQL Serve…
In this article we will see how we can remove partitions from a table in a database in SQL server. In my previous post i had demonstrated how we can partition a table via T-SQL. Lets now remove the partitions and merge the data in a single partition.…
PostgreSQL获取数据库中所有table名: SELECT tablename FROM pg_tables WHERE tablename NOT LIKE 'pg%' AND tablename NOT LIKE 'sql_%' ORDER BY tablename; PostgreSQL获取数据库中所有table名及table的注解信息: SELECT tablename, obj_description(relfilenode, 'pg_class') FROM pg_tables…
命令:su - postgres CREATE USER foo WITH PASSWORD 'secret'; ==================== 1.2个配置修改 postgresql.conf:修改 listen_addresses = '*' pg_hba.conf:增加 # IPv4 local connections:host all all 127.0.0.1/32 md5host all …
--if cloumn exist SELECT EXISTS (SELECT 1 FROM information_schema.columns WHERE table_schema='ent' AND table_name='AdsPlatform' AND column_name='Name'); --add cloumn ALTER TABLE finance."MappingInfo" ADD COLUMN IF NOT EXISTS "Active" b…
在修改表字段类型的时候使用Using来进行显示的转换类型. 原文说明: SET DATA TYPE This form changes the type of a column of a table. Indexes and simple table constraints involving the column willbe automatically converted to use the new column type by reparsing the originally supp…
apple=# create table test(id integer, info text); CREATE TABLE apple=# insert into test select generate_series(1, 100000), md5('test'); INSERT 0 100000 apple=# select * from test limit 1; id | info ----+---------------------------------- 1 | 098f6bcd…
原文地址:Css设置table网格线(无重复)作者:依然贰零零柒 效果图: <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0Transitional//EN""http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <htmlxmlns="http://www.w3.org/1999/xhtml"> <head>…
2down vote according to Documentation VACUUM reclaims storage occupied by dead tuples. But according to this post Dead rows are deleted rows that will later be reused for new rows from INSERTs or UPDATEs. Some dead rows (or reserved free space) can b…
why we need partitions The first and most demanding reason to use partitions in a database is to increase the performance of the database. This is achieved by partition-wise joins; if a user’s queries perform a lot of full-table scans, partitioning w…
warehouse_db=# create table item (item_id integer not null,item_name text,item_price numeric,item_data text);CREATE TABLEwarehouse_db=# create index item_idx on item(item_id);CREATE INDEX warehouse_db=# \di item_idx List of relations Schema | Name |…
http://codeofrob.com/entries/sqlite-csharp-and-nhibernate.html https://code.google.com/archive/p/csharp-sqlite/downloads https://github.com/davybrion/NHibernateWorkshop MySQL sql: #my sql test DROP TABLE Department; CREATE TABLE Department ( Id INT A…
