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Join vs. sub-query
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@user1735921 sure, especially when the query gets so complicated that it does the wrong thing and you spend a day fixing it... there's a balance in between, as usual.
– fabio.sussetto
Nov 30 '17 at 14:29
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Linux下部署企业级邮件服务器(postfix + dovecot + extmail) - 开源 & Gith...
...空格或tab的文本行视为上一行的延续；
5、启动postfix,连接发信
四、为postfix开启基于cyrus-sasl认证功能
1、检查postfix是否支持cyrus-sasl认证
postconf -a
2、配置postfix的主配置文件
vim /etc/postfix/main.cf
在最后添加以下内容
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Logstash实践: 分布式系统的日志监控 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...Redis接收日志，写入到本地文件。
Broker：日志Hub，用来连接多个Shipper和多个Indexer。
无论是Shipper还是Indexer，Logstash始终只做前面提到的3件事：
Shipper从日志文件读取最新的行文本，经过处理（这里我们会改写部分元数据）...
初窥InnoDB的Memcached插件 - 大数据 & AI - 清泛网 - 专注C/C++及内核技术
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separator：Memcached只识别单值，使用此分隔符（|）来连接多个字段的值。
table_map_delimiter：通过此分隔符（.）来确认表和键，如：@@table.key。
如果我们想通过Memcached协议来访问一个表，需要先在containers中配置它：
mysql> ...
Why is transposing a matrix of 512x512 much slower than transposing a matrix of 513x513?
... matrix (64-bit int).
The critical stride would be 2048 bytes, which correspond to 4 rows of the matrix (which is continuous in memory).
Assume we're processing row 28. We're attempting to take the elements of this row and swap them with the elements from column 28. The first 8 elements of the r...
Declaration/definition of variables locations in ObjectiveC?
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I can understand your confusion. Especially since recent updates to Xcode and the new LLVM compiler changed the way ivars and properties can be declared.
Before "modern" Objective-C (in "old" Obj-C 2.0) you didn't have a lot of choices. Instance variables u...
Which is faster: Stack allocation or Heap allocation
...single instruction on most architectures, in most cases, e.g. on x86:
sub esp, 0x10
(That moves the stack pointer down by 0x10 bytes and thereby "allocates" those bytes for use by a variable.)
Of course, the stack's size is very, very finite, as you will quickly find out if you overuse stack all...
Python assigning multiple variables to same value? list behavior
...ual sense is ok (perhaps with a disclaimer that implementations may vary), esp if the goal is to convey behavior.
– Levon
Aug 5 '15 at 14:47
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How to compute the similarity between two text documents?
... between them. Any textbook on information retrieval (IR) covers this. See esp. Introduction to Information Retrieval, which is free and available online.
Computing Pairwise Similarities
TF-IDF (and similar text transformations) are implemented in the Python packages Gensim and scikit-learn. In th...
Why do people say that Ruby is slow? [closed]
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First of all, slower with respect to what? C? Python? Let's get some numbers at the Computer Language Benchmarks Game:
Ruby 1.9 vs. Python3 within the same order of magnitude
Ruby 1.9 vs. PHP within the same order of magnitude
Ruby 1.9 vs. Java 6 ...