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How to speed up insertion performance in PostgreSQL
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If you happend to insert colums with UUIDs (which is not exactly your case) and to add to @Dennis answer (I can't comment yet), be advise than using gen_random_uuid() (requires PG 9.4 and pgcrypto module) is (a lot) faster than uuid_generate_v4()
=# explain anal...
内存管理内幕:动态分配的选择、折衷和实现 - C/C++ - 清泛网 - 专注C/C++及内核技术
...的版本非常类似的基本结构,但是它加入了索引,这使得搜索速度更快,并且可以将多个没有被使用的块组合为一个大的块。它还支持缓存,以便更快地再次使用最近释放的内存。 ptmalloc 是 Doug Lea Malloc 的一个扩展版本,支持多...
“21天教你学会C++” - 创意 - 清泛网 - 专注C/C++及内核技术
...,而只需要几天甚至几小时。我在Amazon.com上进行了如下搜索:
pubdate: after 1992 and title: days and (title: learn or title: teach yourself)
(出版日期:1992年后 and 书名:天 and (书名:学会 or 书名:无师自通))
我一共得到了248个搜索...
Rails 4: List of available datatypes
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For Postgres there is additionally a uuid type which can be used as normal field like t.uuid :name... or as primary key like create_table :users, id: :uuid do... or e.g. t.primary_key :id, :uuid, :default => 'uuid_generate_v1()'
– TNT
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Boost.Asio的简单使用(Timer,Thread,Io_service类) - C/C++ - 清泛网 - 专注C/C++及内核技术
...造出void(const boost::asio::error&)形式的函数.
注意,这里没有指定boost::asio::placeholders::error占位符,因为这个print成员函数没有接受一个error对象作为参数.
timer_.async_wait(boost::bind(&printer::print, this));
在类的折构函数中我们输出最后一...
Vsphere 6 集群上 安装 oracle rac 遇到的共享磁盘故障 - 数据库(内核) - ...
...示 不能访问物理存储
第一次死机
对比互联网上搜索到的方法对比 发现SCSI总线不一样。
参考文档http://www.doc88.com/p-5416264066182.html
按照网上的方法,修改SCSI 控制1的总线为LSI Logic 并行。修改好后,开启虚拟机的电源...
Mocking static methods with Mockito
...ception occurred while fetching localhost address", e);
return UUID.randomUUID().toString();
}
}
}
My test class:
@RunWith(PowerMockRunner.class)
@PrepareForTest(SmokeRouteBuilder.class)
public class SmokeRouteBuilderTest {
@Test
public void testSmokeMessageId_exce...
Add a reference column migration in Rails 4
...cument if someone has the same problem...
In my situation I've been using :uuid fields, and the above answers does not work to my case, because rails 5 are creating a column using :bigint instead :uuid:
add_reference :uploads, :user, index: true, type: :uuid
Reference: Active Record Postgresql UUID...
从源代码剖析Mahout推荐引擎 - 大数据 & AI - 清泛网 - 专注C/C++及内核技术
...考的用户。
近邻算法分为2种:
NearestNUserNeighborhood:指定N的个数,比如,选出前10最相似的用户。
ThresholdUserNeighborhood:指定比例,比如,选择前10%最相似的用户。
6. 推荐算法工具集
推荐算法是以Recommender作为基础的父类...
Getting MAC Address
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Python 2.5 includes an uuid implementation which (in at least one version) needs the mac address. You can import the mac finding function into your own code easily:
from uuid import getnode as get_mac
mac = get_mac()
The return value is the mac...
