I believe you can use...

    RESET QUERY CACHE;

...if the user you&#39;re running as has reload rights. Alternatively, you can defragment the query cache via...

    FLUSH QUERY CACHE;

See the [Query Cache Status and Maintenance][1] section of the MySQL manual for more information.


  [1]: http://dev.mysql.com/doc/refman/5.0/en/query-cache-status-and-maintenance.html

In my system (Ubuntu 12.04) I found `RESET QUERY CACHE` and even restarting mysql server not enough. This was due to [memory disc caching][1].  
After each query, I clean the disc cache in the terminal:  

    sync &amp;&amp; echo 3 | sudo tee /proc/sys/vm/drop_caches

and then reset the query cache in mysql client:

    RESET QUERY CACHE;

  [1]: https://askubuntu.com/questions/155768/how-do-i-clean-or-disable-the-memory-cache

according the [documentation][1], this should do it...

    RESET QUERY CACHE 


  [1]: http://dev.mysql.com/doc/refman/5.0/en/query-cache-status-and-maintenance.html

How can I tell git to ignore my local file and take the one from my remote branch without trying to merge and causing conflicts?

git replace local version with remote version

I want to call a settings file for a variable. How can I do this in Bash?

The settings file will define the variables (for example, CONFIG.FILE):

    production=&quot;liveschool_joe&quot;
    playschool=&quot;playschool_joe&quot;

And the script will use these variables in it:

    #!/bin/bash
    production=&quot;/REFERENCE/TO/CONFIG.FILE&quot;
    playschool=&quot;/REFERENCE/TO/CONFIG.FILE&quot;
    sudo -u wwwrun svn up /srv/www/htdocs/$production
    sudo -u wwwrun svn up /srv/www/htdocs/$playschool

How can I get Bash to do something like that? Will I have to use [AWK][1], [sed][2], etc.?

  [1]: https://en.wikipedia.org/wiki/AWK
  [2]: https://en.wikipedia.org/wiki/Sed






How can I reference a file for variables using Bash?

Is there any way to **clear** mysql **query cache** without restarting mySQL server?

Clear MySQL query cache without restarting server

Is there any way to clear mysql query cache without restarting mySQL server?

What&#39;s the difference in `int(11)` and `int(11) UNSIGNED` ?

What&#39;s the difference in int(11) and int(11) UNSIGNED?

Say I have a select

    SELECT DISTINCT id, customer_id, domain FROM config WHERE type = &#39;foo&#39;;

which returns some records.

How can I do an insert for reach row in the result set like

    INSERT INTO config (id, customer_id, domain) VALUES (@id, @customer_id, &#39;www.example.com&#39;);

where `@id` and `@customer_id` are the fields of the row in the result set?

edit: I didn&#39;t want to just duplicate it, but insert a new value in the field `domain` instead. Nevertheless a facepalm-situation as it&#39;s plain easy ;-) Thanks!

MySQL: How to insert a record for each result in a SQL query?

I am an Amazon RDS customer and am experiencing daily amazon RDS write latency spikes, corresponding roughly to the backup window. I will also see spikes at the end of a snapshot (case in point: running a snapshot takes appx 1 hour, and in the final 5 minutes, write latency spikes). I am running a multi-AZ m1.large deployment. 

Is there anyone on Stack who can explain how Amazon RDS backup is *actually* working?  I&#39;ve read the Amazon RDS docs, and as far as I can tell, Amazon RDS is not behaving according to spec. Specifically, these backup/snapshot operations should be hitting my replica, and therefore not causing any downtime/performance hit, or so I thought. 

I can distill my problem into six questions:

* What is technically happening during a snapshot and a backup, and how are they different? (If you answer this question, please tell me if you are able to empirically confirm your answer, or are simply quoting me documentation).
* Is a spike in write latency to be expected during the backup window on a multi-AZ deployment?
* Is a spike in write latency to be expected at the end of a snapshot on a multi-AZ deployment?
* Would my write latency spike be even higher if I was not multi-AZ ?
* Architecturally, would I be able to avoid these write latency spikes if I rolled my own database running on two m1.large EC2 instances? 
* Are there any configurations I can use that would avoid these write latency spikes while still hosting my DB with RDS, or am I effectively at the mercy of Amazon? 

Bonus Question: where and how do you host your mysql database?

I can say that I have been generally happy with RDS except for these daily write latency issues. I love the built-in database monitoring and it was fairly simple to setup and get going. 

Thanks!

![amazon RDS write latency][1]


  [1]: http://i.stack.imgur.com/YgyYB.png

How does Amazon RDS backup/snapshot actually work?

I&#39;m trying to move old data from:

    this_table &gt;&gt; this_table_archive

copying all columns over.  I&#39;ve tried this, but it doesn&#39;t work:

    INSERT INTO this_table_archive (*) VALUES (SELECT * FROM this_table WHERE entry_date &lt; &#39;2011-01-01 00:00:00&#39;);

Note: the tables are identical and have `id` set as a primary key.

INSERT INTO...SELECT for all MySQL columns

I just want to know what is the benefit/usage of defining **`ZEROFILL`** for `INT` DataType in `MySQL`?

    `id` INT UNSIGNED ZEROFILL NOT NULL 

What is the benefit of zerofill in MySQL?

I&#39;m working on developing a web application with Spring 3 and Hibernate 3.6. At the moment I try to understand how Caching with Spring and Hibernate works. I found some sources about Caching with Hibernate and some about Spring and I try to bring my information together now. I still got some questions to both frameworks and I&#39;d be glad if someone could answer them or tell me if the facts listed here are correct.

Most of the time, short answers (yes/no) would be sufficient. I think that this list can be useful for others too, who want to understand how caching with spring and hibernate works.

`General`

**1)** Hibernate supports the following Caches: 1st Level Cache, 2nd Level Cache, Query Cache

**2)** Spring itself supports the following Caching possibilities: just Method Caching 

`1st Level Cache`

**3)** The 1st Level Cache is part of EVERY Hibernate application. 

**4)** The 1st Level Cache is created for EVERY hibernate-session. 

**5)** What is saved in the 1st Level Cache? Objects or just the values of their properties? queries and their results?

`2nd Level Cache`

**6)** I found out: the 2nd Level Cache is used ONCE per application. isn&#39;t that false? isn&#39;t it used ONCE per `SessionFactory`? and: multiple sessionfactorys = multiple 2nd level caches possible?

**7)** what is saved in the 2nd Level Cache: in my opinion just the values belonging to one record, not the objects itself.

**8)** when storing values from one record in 2nd Level Cache, its possible to store related values (from objects connected over a foreign key) with it too?

**9)** when updating the values of one object in the 2nd level cache, it&#39;s possible to update the values of objects connected with it in the cache too?

**10)** when values of an object are changing, how can I update the 2nd level cache? flush? can I just update a part of the cache or must the whole cache be updated?

**11)** where does the 2nd level cache make sense and where doesn&#39;t it?

**12)** the Cache Mode: does each cache mode provide a different strategy of caching? for example with cache mode &quot;read-only&quot; no synchronization of database and cache is ever necessary? do other cache modes provide synchronization? I thought synchronization must be done by the developer himself?

`Query Cache`

**13)** what is the difference between the Query Cache and the 2nd Level Cache? in my opinion: in the Query Cache result sets are saved, but not with their values, just with their ids. when the query is used again and the result set is still &quot;correct&quot;, the values belonging to the ids are queried from the 2nd Level Cache

**14)** For the Query Cache a 2nd Level Cache MUST be used?

**15)** where does the Query Cache make sense and where doesn&#39;t it?

`Spring`

**16)** Does Spring provide more Caching possibilities than method caching?

**17)** method caching is not linked to hibernate caching

**18)** but: for method caching the 2nd level is necessary, like Ehcache (which can be used by hibernate too)

**19)** can method caching be used without database queries?

`Getting mixed up`

**20)** if using ehcache for hibernate as 2nd level cache and Ehcache for spring for method caching, can I use the same Ehcache-instance? is there a chance that something gets mixed up?

**21)** when using 1st level cache and 2nd level cache, can they get mixed up? when querying the database, where does the result then come from, the 1st or 2nd level cache? does the 1st level cache work with the 2nd level cache?

**22)** anything else that can get mixed up by using the caches I mentioned? :-)

Thanks for answering, no matter what question! :-)


Caching with Hibernate + Spring - some Questions

Simple, probably dumb question: Suppose I have a Java server that stores in memory commonly used keys and values which I can query (let&#39;s say in a HashMap)

What&#39;s the difference between that and using Memcache (or even Redis)? They both store things in memory. Is there a benefit to one or the other? Does Memcache leaves less of a memory footprint? Can store more in less memory? Faster to query? No difference?

Memcache vs Java Memory

I am modifying a site&#39;s appearance (CSS modifications) but can&#39;t see the result on Chrome because of annoying persistent cache. I tried &lt;kbd&gt;Shift&lt;/kbd&gt;+refresh but it doesn&#39;t work.

How can I disable the cache temporarily or refresh the page in some way that I could see the changes?

Disabling Chrome cache for website development

Jonathan suggest here: https://stackoverflow.com/questions/4980296/xcode-includes-xib-files-that-have-been-deleted/4980405#4980405 that cleaning all targets and empty the caches will fix the problem with Xcode including deleted .xib files but I cannot find a way to empty the cache in Xcode 4.

How to do that in Xcode 4?


How to Empty Caches and Clean All Targets Xcode 4 and later

I&#39;m having difficulty finding a clear-cut, practical explanation for what is the correct way to leverage browser caching to increase page speed.  

According to [this site][1]:

&gt; It is important to specify one of Expires or Cache-Control max-age,
&gt; and one of Last-Modified or ETag, for all cacheable resources. It is
&gt; redundant to specify both Expires and Cache-Control: max-age, or to
&gt; specify both Last-Modified and ETag.

Is this correct? If so, should I use `Expires` or `max-age`? I think I have a general understanding of what both of those are but don&#39;t know which is usually best to use. 

If I have to also do `Last-Modified` or `ETag`, which one of those? I think I get `Last-Modified` but am still very fuzzy on this `ETag` concept. 

Also, which files should I enable browser caching for?

  [1]: http://code.google.com/speed/page-speed/docs/caching.html#LeverageBrowserCaching

Content Type	Original Author	Original Content on Stackoverflow
Question	Mahoor13	View Question on Stackoverflow
Solution 1 - Mysql	John Parker	View Answer on Stackoverflow
Solution 2 - Mysql	Leszek	View Answer on Stackoverflow
Solution 3 - Mysql	Manu Eidenberger	View Answer on Stackoverflow

Clear MySQL query cache without restarting server

Mysql Problem Overview

Mysql Solutions

Solution 1 - Mysql

Solution 2 - Mysql

Solution 3 - Mysql

How can I reference a file for variables using Bash?

git replace local version with remote version

Attributions