Does it matter how many files I keep in a single directory? If so, how many files in a directory is too many, and what are the impacts of having too many files? (This is on a Linux server.)

Background: I have a photo album website, and every image uploaded is renamed to an 8-hex-digit id (say, a58f375c.jpg).  This is to avoid filename conflicts (if lots of &quot;IMG0001.JPG&quot; files are uploaded, for example).  The original filename and any useful metadata is stored in a database.  Right now, I have somewhere around 1500 files in the images directory.  This makes listing the files in the directory (through FTP or SSH client) take a few seconds.  But I can&#39;t see that it has any effect other than that.  In particular, there doesn&#39;t seem to be any impact on how quickly an image file is served to the user.

I&#39;ve thought about reducing the number of images by making 16 subdirectories: 0-9 and a-f.  Then I&#39;d move the images into the subdirectories based on what the first hex digit of the filename was.  But I&#39;m not sure that there&#39;s any reason to do so except for the occasional listing of the directory through FTP/SSH.

How many files can I put in a directory?

How many pointers (`*`) are allowed in a single variable?

Let&#39;s consider the following example.

    int a = 10;
    int *p = &amp;a;

Similarly we can have

    int **q = &amp;p;
    int ***r = &amp;q;

and so on.

For example,

    int ****************zz;



How many levels of pointers can we have?

I have come up against this problem a few times at inopportune moments:

* Trying to work on open source Java projects with deep paths
* Storing deep Fitnesse wiki trees in source control
* An error trying to use Bazaar to import my source control tree

Why does this limit exist? 

Why hasn&#39;t it been removed yet?  

How do you cope with the path limit? 
And no, switching to Linux or Mac OS X is not a valid answer to this question ;)

Why does the 260 character path length limit exist in Windows?

How many characters are allowed to be in the subject line of Internet email?
I had a scan of [The RFC for email][1] but could not see specifically how long it was allowed to be.
I have a colleague that wants to programmatically validate for it.

If there is no formal limit, what is a good length in practice to suggest?


  [1]: http://www.w3.org/Protocols/rfc822/

What is the email subject length limit?

Scenario in short: A table with more than 16 million records [2GB in size]. The higher LIMIT offset with SELECT, the slower the query becomes, when using     ORDER BY *primary_key*

So  

    SELECT * FROM large ORDER BY `id`  LIMIT 0, 30 

takes far less than  

    SELECT * FROM large ORDER BY `id` LIMIT 10000, 30 

That only orders 30 records and same eitherway. So it&#39;s not the overhead from ORDER BY.  
Now when fetching the latest 30 rows it takes around 180 seconds. How can I optimize that simple query?


Why does MYSQL higher LIMIT offset slow the query down?

In PostgreSQL there is the `Limit` and `Offset` keywords which will allow very easy pagination of result sets. 

What is the equivalent syntax for SQL Server? 

Equivalent of LIMIT and OFFSET for SQL Server?

What is the upper limit of records for MySQL database table. I&#39;m wondering about autoincrement field. What would happen if I add milions of records? How to handle this kind of situations?
Thx!

Maximum number of records in a MySQL database table

Lately I have been using GitHub and I am wondering what is the repository size limit for files hosted on github.com?  I have been wondering this because I was thinking of using GitLab, since it allows 10 GB for each repository.

Repository size limits for GitHub.com

I have an issue with a systemd config for ElasticSearch.

    [Unit]
    Description=platform-elasticsearch
    After=syslog.target network.target remote-fs.target nss-lookup.target
    
    [Service]
    User={{ app_user }}
    Group={{ app_group }}
    Environment=ES_PATH_CONF=/platform/opt/elasticsearch-{{ elasticsearch.version }}/config
    Environment=JAVA_HOME=/platform/opt/jdk{{ jdk.major_version }}_{{ jdk.minor_version }}
    LimitAS=infinity
    LimitRSS=infinity
    LimitCORE=infinity
    LimitNOFILE=100000
    LimitMEMLOCK=100000
    StandardOutput=syslog
    StandardError=syslog
    WorkingDirectory=/platform/var/app/elasticsearch
    ExecStart=/platform/opt/elasticsearch-{{ elasticsearch.version }}/bin/elasticsearch
    ExecReload=/bin/kill -s HUP $MAINPID
    ExecStop=/bin/kill -s -TERM $MAINPID
    TimeoutStopSec=60
    # When a JVM receives a SIGTERM signal it exits with code 143
    SuccessExitStatus=143 0
    Type=simple
    Restart=on-failure
    RestartSec=10
    PIDFile=/platform/var/run/elasticsearch.pid
    
    [Install]
    WantedBy=multi-user.target

This does not seem to let me configure the vm.max_map_count setting.

    Jul 20 14:53:46 scratchpad elasticsearch: [2018-07-20T14:53:46,359][INFO ][o.e.b.BootstrapChecks    ] [1oQJNUK] bound or publishing to a non-loopback     address, enforcing bootstrap checks
    Jul 20 14:53:46 scratchpad elasticsearch: ERROR: [1] bootstrap checks failed
    Jul 20 14:53:46 scratchpad elasticsearch: [1]: max virtual memory areas vm.max_map_count [65530] is too low, increase to at least [262144]
    Jul 20 14:53:46 scratchpad elasticsearch: [2018-07-20T14:53:46,376][INFO ][o.e.n.Node               ] [1oQJNUK] stopping ...
    Jul 20 14:53:46 scratchpad elasticsearch: [2018-07-20T14:53:46,414][INFO ][o.e.n.Node               ] [1oQJNUK] stopped
    Jul 20 14:53:46 scratchpad elasticsearch: [2018-07-20T14:53:46,414][INFO ][o.e.n.Node               ] [1oQJNUK] closing ...
    Jul 20 14:53:46 scratchpad elasticsearch: [2018-07-20T14:53:46,445][INFO ][o.e.n.Node               ] [1oQJNUK] closed
    Jul 20 14:53:46 scratchpad systemd: platform-elasticsearch.service: main process exited, code=exited, status=78/n/a

The specific issue is the following:

    Jul 20 14:53:46 scratchpad elasticsearch: [1]: max virtual memory areas vm.max_map_count [65530] is too low, increase to at least [262144]


I have been able to start elastic search on the commandline with the following:

    sudo su -c &#39;echo 262144 &gt; &quot;/proc/sys/vm/max_map_count&quot;&#39; &amp;&amp; \ 
    export JAVA_HOME=/platform/opt/jdk1.8.0_181 &amp;&amp; \
    export ES_PATH_CONF=/platform/opt/elasticsearch-6.3.1/config &amp;&amp; \
    /platform/opt/elasticsearch-6.3.1/bin/elasticsearch 

can anyone tell me why LimitMEMLOCK=100000 does not work, and how I can effectively set max_map_count from within systemd.

I have also tried to set the following:

    cat /etc/security/limits.d/30_elastic_limits.conf

    vagrant       hard    nofile     500000
    vagrant       hard    memlock     262144

but this seems to be totally ignored by systemd.

Elasticsearch: Max virtual memory areas vm.max_map_count [65530] is too low, increase to at least [262144]

I&#39;m trying to do something like :

    SELECT * FROM table LIMIT 10,20

or

    SELECT * FROM table LIMIT 10 OFFSET 10

but using SQL Server

The only [solution I found][1] looks like overkill:

    SELECT * FROM ( 
      SELECT *, ROW_NUMBER() OVER (ORDER BY name) as row FROM sys.databases 
     ) a WHERE row &gt; 5 and row &lt;= 10

I also [found][2]:

    SELECT TOP 10 * FROM stuff; 

... but it&#39;s not what I want to do since I can&#39;t specify the starting limit.

Is there another way for me to do that ? 

Also, just curious, is there a reason why doesn&#39;t SQL Server support the `LIMIT` function or something similar? I don&#39;t want to be mean, but that really sounds like something a DBMS needs ... If it does, then I&#39;m sorry for being so ignorant! I&#39;ve been working with MySQL and SQL+ for the past 5 years so...


  [1]: http://blogs.msdn.com/sqlserver/archive/2006/10/25/limit-in-sql-server.aspx
  [2]: http://vorg.ca/626-the-MS-SQL-equivalent-to-MySQLs-limit-command

LIMIT 10..20 in SQL Server

I know `ls -t` will list all files by modified time.  But how can I limit these results to only the last *n* files?

How can I list (ls) the 5 last modified files in a directory?

For pagination purposes, I need a run a query with the `LIMIT` and `OFFSET` clauses. But I also need a count of the number of rows that would be returned by that query without the `LIMIT` and `OFFSET` clauses.

I want to run:

    SELECT * FROM table WHERE /* whatever */ ORDER BY col1 LIMIT ? OFFSET ?

And:

    SELECT COUNT(*) FROM table WHERE /* whatever */

At the same time.  Is there a way to do that, particularly a way that lets Postgres optimize it, so that it&#39;s faster than running both individually?

Run a query with a LIMIT/OFFSET and also get the total number of rows

I have simple question with Sqlite. What is the difference between this:

    Select * from Animals LIMIT 100 OFFSET 50

and

    Select * from Animals LIMIT 100,50


Sqlite LIMIT / OFFSET query

I have a simple webform that will allow unauthenticated users to input their information, including name. I gave the name field a limit of 50 characters to coincide with my database table where the field is `varchar(50)`, but then I started to wonder.

Is it more appropriate to use something like the `Text` column type or should I limit the length of the name to something reasonable?

I&#39;m using SQL Server 2005, in case that matters in your response.

**EDIT:** I did not see [this broader question][1] regarding similar issues.


  [1]: https://stackoverflow.com/questions/20958/list-of-standard-lengths-for-database-fields

What is a reasonable length limit on person &quot;Name&quot; fields?

Is there a limit to the length of a GET request?

I heard that HTTP POST has no specification limit in data size it can be sent by. Is that true or is there just some really high limit?

Can HTTP POST be limitless?

This is mine

        $art = Article::where(&#39;id&#39;,$article)-&gt;firstOrFail();
		$products = $art-&gt;products;

I just wanna take a limit &#39;product&#39;
This is wrong way
      
       $products = $art-&gt;products-&gt;offset($offset*$limit)-&gt;take($limit)-&gt;get();

Please give me a hand!

Thanks!

Laravel Eloquent limit and offset

When I add LIMIT 1 to a MySQL query, does it stop the search after it finds 1 result (thus making it faster) or does it still fetch all of the results and truncate at the end?

Does adding &#39;LIMIT 1&#39; to MySQL queries make them faster when you know there will only be 1 result?

I have a **Jobs** and a **Companies** table, and I want to extract 20 jobs that meet the following criteria: 

1. Jobs only from two (2) named companies  
2. There can at most be 10 jobs per company

I have tried the following `SELECT` with `UNION DISTINCT`, but the problem is that the `LIMIT 0,10` applies to the whole result set. I want it to apply to each of the companies. 

If there aren&#39;t 10 jobs per company, then the query should return all the jobs it finds.

    SELECT c.name, j.title, j.`desc`, j.link 
      FROM jobs_job j
    INNER JOIN companies_company c ON j.company_id = c.id
    WHERE c.name IN (&#39;Company1&#39;)
    UNION DISTINCT
    SELECT c.name, j.title, j.`desc`, j.link 
      FROM jobs_job j
    INNER JOIN companies_company c ON j.company_id = c.id
    WHERE c.name IN (&#39;Company2&#39;)
    ORDER by name, title
    LIMIT 0,10

I am new to MySQL, so realise there may be a smarter way to do this instead of with UNION, so any suggestions for improvements are definitely welcome.

Combining UNION and LIMIT operations in MySQL query

How do you do `LIMIT` in DB2 for iSeries? 

I have a table with more than 50,000 records and I want to return records 0 to 10,000, and records 10,000 to 20,000.

I know in SQL you write  `LIMIT 0,10000` at the end of the query for 0 to 10,000 and `LIMIT 10000,10000` at the end of the query for 10000 to 20,000 

So, how is this done in DB2? Whats the code and syntax?
(full query example is appreciated)



Equivalent of LIMIT for DB2

If I had a million images, would it be better to store them in some folder/sub-folder hierarchy or just dump them all straight into a bucket (without any folders)?

Would dumping all the images into a hierarchy-less bucket slow down LIST operations?

Is there a significant overhead in creating folders and sub folders on the fly and setting up their ACLs (programatically speaking)?

Max files per directory in S3

I want to update rows in my table with starting from 1001 to next 1000.

I tried with following query:

    UPDATE `oltp_db`.`users` SET p_id = 3 LIMIT 1001, 1000

 1. This is giving me syntax error. Is this correct? am I doing any mistake here.
 2. Can we limit update in this way?

Also, the rows that I am trying to update are having Null value for the column p_id which is having data type INTEGER. Due to this I am not even able to update using following query:

    UPDATE `oltp_db`.`users` SET p_id = 3 WHERE p_id = null

 1. Is my above query correct?
 2. What can be done to achieve this?


 

MySQL - UPDATE query with LIMIT

Those &quot;fine&quot; RFCs mandate from every RFC-client that they beware of not using more than 2 connections per host...

Microsoft implemented this in WebClient. I know that it can be turned off with 

App.config:
   
    &lt;?xml version=&quot;1.0&quot; encoding=&quot;utf-8&quot; ?&gt; 
    &lt;configuration&gt; 
     &lt;system.net&gt; 
      &lt;connectionManagement&gt; 
       &lt;add address=&quot;*&quot; maxconnection=&quot;100&quot; /&gt; 
      &lt;/connectionManagement&gt; 
     &lt;/system.net&gt; 
    &lt;/configuration&gt; 

(found on http://social.msdn.microsoft.com/forums/en-US/netfxnetcom/thread/1f863f20-09f9-49a5-8eee-17a89b591007 )

But how can I do it programmatically?

Accordin to
http://msdn.microsoft.com/en-us/library/system.net.servicepointmanager.defaultconnectionlimit.aspx

&quot;Changing the DefaultConnectionLimit property has no effect on existing 
ServicePoint objects; it affects only ServicePoint objects that are 
initialized after the change. If the value of this property has not been 
set either directly or through configuration, the value defaults to the 
constant DefaultPersistentConnectionLimit.&quot;


I&#39;d like best to configure the limit when I instanciate the WebClient, but just removing this sad limitation programmatically at the start of my programm would be fine, too.


The server I access is not a regular webserver in the internet, but under my control and in the local lan. I want to do API-calls, but I don&#39;t use webservices or remoting

How can I programmatically remove the 2 connection limit in WebClient

I want to join two tables, but only get 1 record of table2 per record on table1

For example:

    SELECT c.id, c.title, p.id AS product_id, p.title
    FROM categories AS c
    JOIN products AS p ON c.id = p.category_id

This would get me all records in `products`, which is not what I want. I want 1 [the first] product per category (I have a `sort` column in the products field).

How do I go about doing that?

MySQL JOIN with LIMIT 1 on joined table

I am getting some client-side Javascript stack overflow issues specifically in IE browser, 
this is happening inside a third party library that makes some function calls and for some reason they occasionally brake in IE only due to it&#39;s low stack limit. 

I then coded a small test HTML to test the stack size limit for some browsers and found that IE8 has actually a small stack limit if compared to FF 7 or Chrome 14 running on a Laptop with Windows 7 OS, 8Gb RAM:

    &lt;html&gt;
    &lt;body&gt;
    
    &lt;!-- begin Script: --&gt;
    &lt;script type=&quot;text/javascript&quot;&gt;
    
    function doSomething(){

      var i = 3200;
      doSomethingElse(i);
    
    }
    
    function doSomethingElse(i){
      if (i == 0) return -1;
      doSomethingElse(i-1);
    }

    doSomething(); 

    &lt;/script&gt;
    &lt;!-- END OF PAGE --&gt;
    
    &lt;/body&gt;
    &lt;/html&gt;


IE raises stack overflow when the values are around 3200, Firefox and Chrome can handle a very deep recursion if compared to IE.

I would like to know if there&#39;s a way to tie the stack-overflow exception with the Javascript function that raised it during runtime in IE or any other browser and if it could give the stacktrace with the chain of function in the stack at the moment the error was raised.

Browser Javascript Stack size limit

The logic is of the model is:  

 - A `Building` has many `Rooms`
 - A `Room` may be inside another `Room` (a closet, for instance--ForeignKey on &#39;self&#39;)  
 - A `Room` can only be inside another `Room` in the same building (this is the tricky part)  
  
Here&#39;s the code I have:  

    #spaces/models.py
    from django.db import models    
    
    class Building(models.Model):
        name=models.CharField(max_length=32)
        def __unicode__(self):
            return self.name

    class Room(models.Model):
        number=models.CharField(max_length=8)
        building=models.ForeignKey(Building)
        inside_room=models.ForeignKey(&#39;self&#39;,blank=True,null=True)
        def __unicode__(self):
            return self.number

and:

    #spaces/admin.py
    from ex.spaces.models import Building, Room
    from django.contrib import admin
    
    class RoomAdmin(admin.ModelAdmin):
        pass

    class RoomInline(admin.TabularInline):
        model = Room
        extra = 2

    class BuildingAdmin(admin.ModelAdmin):
        inlines=[RoomInline]

    admin.site.register(Building, BuildingAdmin)
    admin.site.register(Room)


The inline will display only rooms in the current building (which is what I want).  The problem, though, is that for the `inside_room` drop down, it displays all of the rooms in the Rooms table (including those in other buildings).


In the inline of `rooms`, I need to limit the `inside_room` choices to only `rooms` which are in the current `building` (the building record currently being altered by the main `BuildingAdmin` form). 


I can&#39;t figure out a way to do it with either a `limit_choices_to` in the model, nor can I figure out how exactly to override the admin&#39;s inline formset properly (I feel like I should be somehow create a custom inline form, pass the building_id of the main form to the custom inline, then limit the queryset for the field&#39;s choices based on that--but I just can&#39;t wrap my head around how to do it).

Maybe this is too complex for the admin site, but it seems like something that would be generally useful... 


Limit foreign key choices in select in an inline form in admin

Can someone please tell us/me if the [MAX_PATH issue](https://stackoverflow.com/questions/1880321/why-does-the-260-character-path-length-limit-exist-in-windows) still exists in (the technical preview of) Windows 10. And if it exists: How many characters can a path and an individual file name have?

Does MAX_PATH issue still exists in Windows 10

Depending on the use case, how do I  constrain the number of files that dropzone.js will allow?

For example, I might need to only allow 1, 2, or 4 files uploaded.

It&#39;s not `uploadMultiple`. Unfortunately, `uploadMultiple` only applies to the number of files handled per request.

How to limit the number of dropzone.js files uploaded?

Since everything has a limit, I was wondering if there is a limit to the number of nested `for` loops or as long as I have memory, I can add them, can the Visual Studio compiler create such a program?

Of course a 64 or more nested `for` loops would be not handy to debug, but is it doable?

    private void TestForLoop()
    {
      for (int a = 0; a &lt; 4; a++)
      {
        for (int b = 0; b &lt; 56; b++)
        {
          for (int c = 0; c &lt; 196; c++)
          {
            //etc....
          }
        }
      }
    }


Is there a limit to the number of nested &#39;for&#39; loops?

HTML5&#39;s localStorage databases are usually size-limited — standard sizes are 5 or 10 MB per domain. Can these limits be circumvented by subdomains (e.g. example.com, hack1.example.com and hack2.example.com all have their own 5 MB databases)? And is there anything in the standard that specifies whether parent domains can access their children&#39;s databases? I can&#39;t find anything, and I can see arguments for doing it either way, but it seems like there has to be some standard model.

HTML5 localStorage size limit for subdomains

Currently `ulimit -n` shows `10000`. I want to increase it to `40000`. I&#39;ve edited &quot;/etc/sysctl.conf&quot; and put `fs.file-max=40000`. I&#39;ve also edited `/etc/security/limits.conf` and updated hard and soft values. But still ulimit shows `10000`. After making all these changes I rebooted my laptop. I&#39;ve access to root password.

    usr_name@usr_name-lap:/etc$ /sbin/sysctl fs.file-max
    fs.file-max = 500000

Added following lines in `/etc/security/limits.conf` -

    *     soft    nofile          40000
    *     hard    nofile          40000

I also added following line in `/etc/pam.d/su`-

    session&#160;&#160;&#160; required&#160;&#160; pam_limits.so

I&#39;ve tried every possible way as given on other forums, but I can reach up to a maximum limit of `10000`, not beyond that. What can be the issue?

I&#39;m making this change because `neo4j` throws maximum open file limits reached error.

How to increase Neo4j&#39;s maximum file open limit (ulimit) in Ubuntu?

I am using JPA 2. For safety reasons, I am working type safe with CriteriaQuery&#39;s (and thus, I am not searching for any solutions to typed queries and so on).

I recently came across an issue in which I needed to set a SQL-LIMIT.

After a lot of searching, I was still not successful in finding a solution.

    CriteriaQuery&lt;Product&gt; query = getEntityManager().getCriteriaBuilder().createQuery(Product.class);
    Root&lt;Product&gt; product = query.from(Product.class);
    query.select(product);

    return em.createQuery(query).getResultList();

Can anyone help me?

JPA 2 CriteriaQuery, using a limit

Is there any daily limit for number push notifications (GCM) can be sent to a particular android application user?

Android Push Notification (GCM), is there any Daily Limit?

I am using `ls -l -t` to get a list of files in a directory ordered by time. 

I would like to limit the search result to the top 2 files in the list.&lt;br/&gt;
Is this possible?&lt;br/&gt;
I&#39;ve tried with grep and I struggled.

first two results from ls command

In Python there is a maximum recursion depth. Seems it is because Python is interpreted rather than compiled. Does C++ have the same concept? Or it is connected only with RAM limit?

Does C++ limit recursion depth?

Talking about `Stream`s, when I execute this piece of code

	public class Main {
		public static void main(String[] args) {
			Stream.of(1,2,3,4,5,6,7,8,9)
			.peek(x-&gt;System.out.print(&quot;\nA&quot;+x))
			.limit(3)
			.peek(x-&gt;System.out.print(&quot;B&quot;+x))
			.forEach(x-&gt;System.out.print(&quot;C&quot;+x));
		}
	}

I get this output 

    A1B1C1
    A2B2C2
    A3B3C3

because limiting my stream to the first three components forces actions *A*, *B* and *C* to be executed only three times.

Trying to perform an analogous computation on the last three elements by using `skip()` method, shows a different behaviour: this

	public class Main {
		public static void main(String[] args) {
			Stream.of(1,2,3,4,5,6,7,8,9)
			.peek(x-&gt;System.out.print(&quot;\nA&quot;+x))
			.skip(6)
			.peek(x-&gt;System.out.print(&quot;B&quot;+x))
			.forEach(x-&gt;System.out.print(&quot;C&quot;+x));
		}
	}

outputs this

    A1
    A2
    A3
    A4
    A5
    A6
    A7B7C7
    A8B8C8
    A9B9C9

Why, in this case, actions *A1* to *A6* are being executed? It must have something to do with the fact that *limit* is a [short-circuiting stateful intermediate operation][1], while *skip* is not, but I don&#39;t understand practical implications of this property. Is it just that &quot;every action before *skip* is executed while not everyone before *limit* is&quot;?


  [1]: https://docs.oracle.com/javase/8/docs/api/java/util/stream/Stream.html#limit-long-

Java 8 Stream: difference between limit() and skip()

I recently had a Linux process which “leaked” file descriptors: It opened them and didn&#39;t properly close some of them.

If I had monitored this, I could tell – in advance – that the process was reaching its limit.

Is there a nice, Bash or Python way to check the FD usage ratio for a given process in a Ubuntu Linux system?

**EDIT:**

I now know how to check how many open file descriptors are there; I only need to know **how many file descriptors are allowed for a process**. Some systems (like Amazon EC2) don&#39;t have the `/proc/pid/limits` file.

Check the open FD limit for a given process in Linux

What I want to do is SUM a column, but also COUNT the number of rows it is summing, with a limit of no more than 5 rows. So my query is:

    SELECT COUNT(*), SUM(score) FROM answers WHERE user=1 LIMIT 5

What I expected back was a COUNT(*) up to 5 (I cant just assume it will always be 5 in my code logic as it could have less than 5 answers), with a sum of the score of the *up to* 5 rows.

Instead what I seem to get back is the total number of matching rows (where user is 1) as the count, and the sum of the score for those rows. The numbers don&#39;t change whether I put `LIMIT 1` or `LIMIT 5` or even `LIMIT 50`.

What I believe will work in this situation is this instead

    SELECT COUNT(*), SUM(score) FROM (SELECT * FROM answers WHERE user=1 LIMIT 5) AS a

But that seems a little convoluted for such a simple query, and as it&#39;s in a high traffic script, I want it to be as performant as possible.

Am I missing something? I did find [this bug report](http://bugs.mysql.com/bug.php?id=50005) from a few years back which seems to be related to this &quot;problem&quot;, but I&#39;m assuming it&#39;s not actually a bug?


MySQL COUNT with LIMIT

    from f in CUSTOMERS
    where depts.Contains(f.DEPT_ID)
    select f.NAME

`depts` is a list (`IEnumerable&lt;int&gt;`) of department ids

This query works fine until you pass a large list (say around 3000 dept ids) .. then I get this error:

&gt; The incoming tabular data stream (TDS) remote procedure call (RPC) protocol stream is incorrect. Too many parameters were provided in this RPC request. The maximum is 2100.

I changed my query to: 

    var dept_ids = string.Join(&quot; &quot;, depts.ToStringArray());
    from f in CUSTOMERS
    where dept_ids.IndexOf(Convert.ToString(f.DEPT_id)) != -1
    select f.NAME

using `IndexOf()` fixed the error but made the query slow. Is there any other way to solve this? thanks so much.

Hitting the 2100 parameter limit (SQL Server) when using Contains()

I was just simply wondering how I could limit the length of a string in C#.

    string foo = &quot;1234567890&quot;;
Say we have that. How can I limit foo to say, 5 characters?

C#: Limit the length of a string?

My queries get very slow when I add a `limit 1`.
  
I have a table `object_values`  with timestamped values for objects:

     timestamp |  objectID |  value
    --------------------------------
     2014-01-27|       234 | ksghdf

Per object I want to get the latest value:

    SELECT * FROM object_values WHERE (objectID = 53708) ORDER BY timestamp DESC LIMIT 1;
(I cancelled the query after more than 10 minutes)

This query is very slow when there are no values for a given objectID (it is fast if there are results).
If I remove the limit it tells me nearly instantaneous that there are no results:

    SELECT * FROM object_values WHERE (objectID = 53708) ORDER BY timestamp DESC;  
    ...  
    Time: 0.463 ms

An explain shows me that the query without limit uses the index, where as the query with `limit 1` does not make use of the index:

**Slow query:**


    explain SELECT * FROM object_values WHERE (objectID = 53708) ORDER BY timestamp DESC limit 1;  
    QUERY PLAN`
    ----------------------------------------------------------------------------------------------------------------------------
    Limit  (cost=0.00..2350.44 rows=1 width=126)
    -&gt;  Index Scan Backward using object_values_timestamp on object_values  (cost=0.00..3995743.59 rows=1700 width=126)
         Filter: (objectID = 53708)`

**Fast query:**

    explain SELECT * FROM object_values WHERE (objectID = 53708) ORDER BY timestamp DESC;
                                                      QUERY PLAN
    --------------------------------------------------------------------------------------------------------------
     Sort  (cost=6540.86..6545.11 rows=1700 width=126)
       Sort Key: timestamp
       -&gt;  Index Scan using object_values_objectID on working_hours_t  (cost=0.00..6449.65 rows=1700 width=126)
             Index Cond: (objectID = 53708)

The table contains 44,884,559 rows and 66,762 distinct objectIDs.  
I have separate indexes on both fields: `timestamp` and `objectID`.  
I have done a `vacuum analyze` on the table and I have reindexed the table.



Additionally the slow query becomes fast when I set the limit to 3 or higher:

    explain SELECT * FROM object_values WHERE (objectID = 53708) ORDER BY timestamp DESC limit 3;
                                                         QUERY PLAN
    --------------------------------------------------------------------------------------------------------------------
     Limit  (cost=6471.62..6471.63 rows=3 width=126)
       -&gt;  Sort  (cost=6471.62..6475.87 rows=1700 width=126)
             Sort Key: timestamp
             -&gt;  Index Scan using object_values_objectID on object_values  (cost=0.00..6449.65 rows=1700 width=126)
                   Index Cond: (objectID = 53708)

In general I assume it has to do with the planner making wrong assumptions about the exectution costs and therefore chooses for a slower execution plan.

Is this the real reason? Is there a solution for this?

PostgreSQL query very slow with limit 1

I put together a test table for a error I recently came across. It involves the use of LIMIT when attempting to delete a single record from a MySQL table.

The error I speak of is &quot;**You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near &#39;LIMIT 1&#39; at line 1**&quot;


The table I put together is called *test*; it has 3 columns, *id*, *name* and *created*. I populated the table with several records and then attempted to delete one. Below is the statement I used to try and accomplish this.

`DELETE t FROM test t WHERE t.name = &#39;foo&#39; LIMIT 1`

Without the use of LIMIT 1, the statement executes just fine, but of course I wouldn&#39;t be using LIMIT if there wasn&#39;t a need for it.

I&#39;m fully aware that I can use another statement to accomplish this DELETE successfully. See below:
`DELETE FROM test WHERE name = &#39;foo&#39; LIMIT 1`

However my question is centered on why the first statement isn&#39;t working with LIMIT.

So my question is, what I have done incorrectly with respect to the first statement to generate this error? 

MySQL LIMIT on DELETE statement

I am writing a stored procedure where I have an input parameter called *my_size* that is an *INTEGER*. I want to be able to use it in a `LIMIT` clause in a `SELECT` statement. Apparently this is not supported, is there a way to work around this?

    # I want something like:
    SELECT * FROM some_table LIMIT my_size;
    
    # Instead of hardcoding a permanent limit:
    SELECT * FROM some_table LIMIT 100;

Using variable in a LIMIT clause in MySQL

I&#39;m writing a simple script to delete USMT migration folders after a certain amount of days:

    ## Server List ##
    $servers = &quot;Delorean&quot;,&quot;Adelaide&quot;,&quot;Brisbane&quot;,&quot;Melbourne&quot;,&quot;Newcastle&quot;,&quot;Perth&quot;
    
    ## Number of days (-3 is over three days ago) ##
    $days = -3
    
    $timelimit = (Get-Date).AddDays($days)
    
    foreach ($server in $servers)
    {
        $deletedusers = @()
        $folders = Get-ChildItem \\$server\USMT$ | where {$_.psiscontainer}
        write-host &quot;Checking server : &quot; $server
        foreach ($folder in $folders) 
        {
            If ($folder.LastWriteTime -lt $timelimit -And $folder -ne $null)
            {
                $deletedusers += $folder
                Remove-Item -recurse -force $folder.fullname
            }
        }
            write-host &quot;Users deleted : &quot; $deletedusers
            write-host
    }

However I keep hitting the dreaded `Remove-Item : The specified path, file name, or both are too long. The fully qualified file name must be less than 260 characters, and the directory name must be less than 248 characters.`

I&#39;ve been looking at workarounds and alternatives but they all revolve around me caring what is in the folder.

I was hoping for a more simple solution as I don&#39;t really care about the folder contents if it is marked for deletion.

Is there any native Powershell cmdlet other than **Remove-Item -recurse** that can accomplish what I&#39;m after?

Delete directory regardless of 260 char limit

Hay, i have some floats like these

    4.3455
    2.768
    3.67

and i want to display them like this

    4.34
    2.76
    3.67

I don&#39;t want to round the number up or down, just limit the amount of numbers shown after the decimal place to 2.

All Limit Solutions on Gang of Coders

Total of 45 Limit Solutions