大约有 40,000 项符合查询结果（耗时：0.0380秒） [XML]
An explicit value for the identity column in table can only be specified when a column list is used
...tead of
SET IDENTITY_INSERT archive_table ON;
INSERT INTO archive_table
SELECT *
FROM source_table;
SET IDENTITY_INSERT archive_table OFF;
you need to write
SET IDENTITY_INSERT archive_table ON;
INSERT INTO archive_table (field1, field2, ...)
SELECT field1, field2, ...
FROM source_table;...
Hibernate Criteria returns children multiple times with FetchType.EAGER
....class)
.list();
List result = session.createQuery("select o from Order o left join fetch o.lineItems").list();
All of these examples produce the same SQL statement:
SELECT o.*, l.* from ORDER o LEFT OUTER JOIN LINE_ITEMS l ON o.ID = l.ORDER_ID
Want to know why th...
搭建高可用mongodb集群（二）—— 副本集 - 大数据 & AI - 清泛网 - 专注C/...
...切换连接？目前需要手工切换。
主节点的读写压力过大如何解决？
从节点每个上面的数据都是对数据库全量拷贝，从节点压力会不会过大？
数据压力大到机器支撑不了的时候能否做到自动扩展？
这篇文章看完这些问题就...
MySQL: multiple tables or one table with many columns?
...
Recently I was faced with this same problem, because MySQL InnoDB tables have a relatively small length limit (~8000 bytes). In my problem table (data from very lengthy insurance forms, more than 100 columns) we have multiple varchar columns, all UTF8. So we easily filled the ~...
搭建高可用mongodb集群（四）—— 分片 - 大数据 & AI - 清泛网 - 专注C/C++及内核技术
...常是 2个副本 + 1个仲裁。
说了这么多，还是来实战一下如何搭建高可用的mongodb集群：
首先确定各个组件的数量，mongos 3个， config server 3个，数据分3片 shard server 3个，每个shard 有一个副本一个仲裁也就是 3 * 2 = 6 个，总共需要...
Why does Java's hashCode() in String use 31 as a multiplier?
... for 31 since 33 is not a prime:
Of the remaining
four, I'd probably select P(31), as it's the cheapest to calculate on a RISC
machine (because 31 is the difference of two powers of two). P(33) is
similarly cheap to calculate, but it's performance is marginally worse, and
33 is composit...
When should I use Kruskal as opposed to Prim (and vice versa)?
...c.
If you implement both Kruskal and Prim, in their optimal form : with a union find and a finbonacci heap respectively, then you will note how Kruskal is easy to implement compared to Prim.
Prim is harder with a fibonacci heap mainly because you have to maintain a book-keeping table to record the...
从异构软件开发者的角度看异构计算 - 操作系统(内核) - 清泛网 - 专注C/C++...
...此我们应该先对异构的计算平台有一定理解，然后在了解如何在异构平台上执行计算。那到底什么是异构平台呢？首先我们知道现在有很多可以用于计算的单元，诸如CPU，GPU，MIC，DSP，FPGA等等，如果在同一个计算机系统中加入...
SQL JOIN vs IN performance?
...king, IN and JOIN are different queries that can yield different results.
SELECT a.*
FROM a
JOIN b
ON a.col = b.col
is not the same as
SELECT a.*
FROM a
WHERE col IN
(
SELECT col
FROM b
)
, unless b.col is unique.
However, this is the syno...
How to integrate nodeJS + Socket.IO and PHP?
... and making the code more inline with the use of node. Now, PHP can simply select the information from the database.
– blackmambo
Nov 5 '13 at 4:13
...