You shouldn&#39;t put the quotes around the UUID to stop it being interpreted as a string i.e.

    insert into devices (device_id, geohash,name, external_identifier, measures, tags) 
     values 
    (c37d661d-7e61-49ea-96a5-68c34e83db3a,&#39;9q9p3yyrn1&#39;, &#39;Acme1&#39;, &#39;936&#39;, {&#39;aparPower&#39;,&#39;actPower&#39;,&#39;actEnergy&#39;},{&#39;make&#39;:&#39;Acme&#39;});


Alternate: Use `uuid()` function. I have tested this in DevCenter 1.6.0.

```
insert into CHANGE_LOG (someid, modifieddatetime, snum, gnum, source) 
values ( uuid() , &#39;2000-12-12 08:00:00&#39;, &#39;21A&#39;, &#39;&#39;, &#39;system&#39;);
```

How to remove one specific selected file from input file control?

I have an input file control with the option to select multiple files; however, I want to validate a file and if it has an wrong extension then I should remove that file from the file control itself, is it possible?

I tried as below


    &lt;input type=&quot;file&quot; name=&quot;fileToUpload&quot; id=&quot;fileToUpload&quot; multiple/&gt;


    &lt;script&gt; $(&quot;#fileToUpload&quot;)[0].files[0] &lt;/script&gt;

Below is the screenshot of the object but I am not able to modify it

![enter image description here][1]


  [1]: http://i.stack.imgur.com/sIxC6.png

How to remove one specific selected file from input file control

How to change text color of `UISearchBar` in `iOS 7`?

In `iOS 6`, I was subclassing the `UISearchBar` and in `layoutSubviews` customising the properties of `UITextField` subview of `UISearchBar`. 

But in `iOS 7`, `UISearchBar` doesn&#39;t have `UITextField` as its subview. How to fix this?



UISearchBar text color change in iOS 7

Would like to populate some static test data via a CQLsh script.

This doesn&#39;t work:  (device_id is UUID)

    insert into devices (device_id, geohash,name, external_identifier, measures, tags) 
    values (&#39;c37d661d-7e61-49ea-96a5-68c34e83db3a&#39;,&#39;9q9p3yyrn1&#39;, &#39;Acme1&#39;, &#39;936&#39;, {&#39;aparPower&#39;,&#39;actPower&#39;,&#39;actEnergy&#39;},{&#39;make&#39;:&#39;Acme&#39;});

&gt; Bad Request: Invalid STRING constant
&gt; (c37d661d-7e61-49ea-96a5-68c34e83db3a) for device_id of type uuid

I can&#39;t seem to find any CQL function to convert to proper type.  Do I need to do this from a python script?

Thanks,
Chris

Inserting a hard-coded UUID via CQLsh (Cassandra)

Would like to populate some static test data via a CQLsh script.
This doesn't work: (device_id is UUID)
<pre><code class="hljs language-sql">insert into devices (device_id, geohash,name, external_identifier, measures, tags) 
values ('c37d661d-7e61-49ea-96a5-68c34e83db3a','9q9p3yyrn1', 'Acme1', '936', {'aparPower','actPower','actEnergy'},{'make':'Acme'});
</code></pre>
> Bad Request: Invalid STRING constant
> (c37d661d-7e61-49ea-96a5-68c34e83db3a) for device_id of type uuid
I can't seem to find any CQL function to convert to proper type. Do I need to do this from a python script?
Thanks,
Chris

I am trying to insert into my CQL table from the command line. I am able to insert everything. But I am wondering if I have a timestamp column, then how can I insert into timestamp column from the command line? Basically, I want to insert current timestamp whenever I am inserting into my CQL table - 

Currently, I am hardcoding the timestamp whenever I am inserting into my below CQL table -

    CREATE TABLE TEST (ID TEXT, NAME TEXT, VALUE TEXT, LAST_MODIFIED_DATE TIMESTAMP, PRIMARY KEY (ID));
    
    INSERT INTO TEST (ID, NAME, VALUE, LAST_MODIFIED_DATE) VALUES (&#39;1&#39;, &#39;elephant&#39;,  &#39;SOME_VALUE&#39;, 1382655211694);
    
Is there any way to get the current timestamp using some predefined functions in CQL so that while inserting into above table, I can use that method to get the current timestamp and then insert into above table?

How to get current timestamp with CQL while using Command Line?

How am I supposed to bot a new Cassandra node when I get this error?

    INFO [SSTableBatchOpen:1] 2014-02-25 01:51:17,132 SSTableReader.java (line 223) Opening /var/lib/cassandra/data/system/local/system-local-jb-5 (5725 bytes)
    ERROR [main] 2014-02-25 01:51:17,377 CassandraDaemon.java (line 237) Fatal exception during initialization
    org.apache.cassandra.exceptions.ConfigurationException: Saved cluster name Test Cluster != configured name thisisstupid
            at org.apache.cassandra.db.SystemKeyspace.checkHealth(SystemKeyspace.java:542)
            at org.apache.cassandra.service.CassandraDaemon.setup(CassandraDaemon.java:233)
            at org.apache.cassandra.service.CassandraDaemon.activate(CassandraDaemon.java:462)
            at org.apache.cassandra.service.CassandraDaemon.main(CassandraDaemon.java:552)


Name of cluster in the cassandra.yaml file is:


    cluster_name: &#39;thisisstupid&#39;


How do I resolve?

cassandra - Saved cluster name Test Cluster != configured name

The problem that I am having is that I want to run the following command (and I can&#39;t):

    cqlsh &lt; cql_directory/cql_create_stuff.cql

Because I have not logged in to cqlsh.

So I logged in:

    cqlsh -u &#39;my_username&#39; -p &#39;my_super_secret_password&#39;

and now I tried doing the command in cqlsh shell but It just responds with a syntax error.

**Basically, how do I login into cqlsh and run an external CQL script in my file system?** 

How to run cql files (.cql) from within cqlsh?

I want to clarify very basic concept of replication factor and consistency level in Cassandra. Highly appreciate if someone can provide answer to below questions.

RF- Replication Factor
RC- Read Consistency
WC- Write Consistency

2 cassandra nodes (Ex: A, B) RF=1, RC=ONE, WC=ONE or ANY  

 - can I write data to node A and read from node B ?  
 - what will happen if A goes down ?

3 cassandra nodes (Ex: A, B, C) RF=2, RC=QUORUM, WC=QUORUM

 - can I write data to node A and read from node C ? 
 - what will happen if node A goes down ?

3 cassandra nodes (Ex: A, B, C) RF=3, RC=QUORUM, WC=QUORUM

 - can I write data to node A and read from node C ?  
 - what will happen if node A goes down ?

Understand cassandra replication factor versus consistency level

I have been reading articles around the net to understand the differences between the following `key` types. But it just seems hard for me to grasp. Examples will definitely help  make understanding better.

    primary key,
    partition key, 
    composite key 
    clustering key

Difference between partition key, composite key and clustering key in Cassandra?

I&#39;m making a validator based on [UUID](http://en.wikipedia.org/wiki/Universally_unique_identifier) generated by client browser, I use this to identify a certain type data that the user sends; and would like to validate that the `UUID` that client sends it is in fact a valid [Version 4][1] `UUID`.

I found this https://stackoverflow.com/questions/6223185/php-preg-match-uuid-v4, it&#39;s close  but not exactly what I&#39;m looking for. I wish to know if exists something similar to `is_empty()` or `strtodate()` Where if string is not valid Sends `FALSE`.

I could do based on the regular expression but I would like something more native to test it.

Any ideas?

**11/23/2019 EDIT:** About the duplicate tag, while the moderator is technicallly correct, this question was formulated with the goal of fibd something else to regex if existed, and in second place this question has become a reference to Pythoners and PHPers and has a different answers/approach to solve the problem and their answers are better explained in general. This is why I consider this question should be perserved

  [1]: http://en.wikipedia.org/wiki/Universally_unique_identifier#Version_4_.28random.29

How to determine if a string is a valid v4 UUID?

Which version of the UUID should you use? I saw a lot of threads explaining what each version entails, but I am having trouble figuring out what&#39;s best for what applications.

Which UUID version to use?

I am developing an iOS app which calls web-service for login and at that time i send login credentials to web server along with vendor identifier (identifierForVendor),to identify device uniquely for those credentials.So user can have only one device and one credential.

I got identifierForVendor with 

    NSString *uuid = [[UIDevice currentDevice] identifierForVendor].UUIDString

This identifier will then store in database of web server and also in device database.Next time when user opens application and will try to download data from web server firstly local identifierForVendor on users device will compare with identifier stored on web server.

Problem occurs when user uninstall app and reinstall it, I found that identifierForVendor is changed. So user cannot proceed further.

I read apple documentation [UIDevice Documentation][1]


  [1]: https://developer.apple.com/library/ios/documentation/UIKit/Reference/UIDevice_Class/Reference/UIDevice.html#//apple_ref/doc/uid/TP40006902-CH3-SW49

As mention there, if all app from same vendor uninstalls from device then at time of new installation of any app from that vendor will take new identifierForVendor. 

So how to deal with this in my case ?

How to preserve identifierForVendor in ios after uninstalling ios app on device?

Is the Laravel str_random() function random enough so that I can use it for IDs?

For example:

    str_random(32);

This produces a random string of length 32 made up of alphanumeric characters [a-zA-z0-9] (62 characters in total).

Which equates to 2272657884496751345355241563627544170162852933518655225856 possibilities.

However, my question is, is this going to be good enough? Or should I consider using UUIDs or another custom function.



Laravel str_random() or custom function?

I need to create some uniques files in Java and i plan to use UUID.randomUUID to generate their names. Is there any chance to get a collision for this? Should i do something like bellow os I shouldn&#39;t worry about this?

    Integer attemptsToGenerateUUID = 1;
    
    while (true) {
        UUID fileUUID = UUID.randomUUID();
    
        if (fileDoesNotExistwith this UUID name) {
            save file;
            break;
        }
    
        attemptsToGenerateUUID += 1;
    
        if (attemptsToGenerateUUID &gt; 64) {
            return false;
        }
    }


How big is the chance to get a Java UUID.randomUUID collision?

Is there a command to all the rows present in a cql table in cassandra like the one in sql?
    
    delete from TABLE

Going by the documentation, I don&#39;t find any way to perform delete operation without a where condition.

    DELETE col1 FROM SomeTable WHERE userID = &#39;some_key_value&#39;; 

Deleting all rows from Cassandra cql table

Suppose I have a column family:

    CREATE TABLE update_audit (
      scopeid bigint,
      formid bigint,
      time timestamp,
      record_link_id bigint,
      ipaddress text,
      user_zuid bigint,
      value text,
      PRIMARY KEY ((scopeid, formid), time)
      ) WITH CLUSTERING ORDER BY (time DESC)

With two secondary indexes, where `record_link_id` is a high-cardinality column:

    CREATE INDEX update_audit_id_idx ON update_audit (record_link_id);
    
    CREATE INDEX update_audit_user_zuid_idx ON update_audit (user_zuid);

According to my knowledge Cassandra will create two hidden column families like so:

    CREATE TABLE update_audit_id_idx(
        record_link_id bigint,
        scopeid bigint,
        formid bigint,
        time timestamp
        PRIMARY KEY ((record_link_id), scopeid, formid, time)
    );

    CREATE TABLE update_audit_user_zuid_idx(
        user_zuid bigint,
        scopeid bigint,
        formid bigint,
        time timestamp
        PRIMARY KEY ((user_zuid), scopeid, formid, time)
    );

Cassandra secondary indexes are implemented as local indexes rather than being distributed like normal tables. Each node only stores an index for the data it stores.

Consider the following query:

    select * from update_audit where scopeid=35 and formid=78005 and record_link_id=9897;

 1. How will this query execute &#39;under the hood&#39; in Cassandra?
 2. How will a high-cardinality column index (`record_link_id`) affect its performance?
 3. Will Cassandra touch all nodes for the above query? *Why?*
 4. Which criteria will be executed first, base table partition_key or secondary index partition_key? How will Cassandra intersect these two results?


How do secondary indexes work in Cassandra?

I&#39;m new in cassandra, and I have to export the result of a specific query to a csv file.

I found the `COPY` command, but (from what I understand) it allows you only to copy an already existing table to a csv file, and what I want is to copy directly the stdout of my query to the csv file. is there any way to do it with `COPY` command or with another way ?

My command is style (`select column1, column2 from table where condition = xy`) and I&#39;m using `cqlsh`.

Export cassandra query result to a csv file

I&#39;ve just started working with Cassandra (datastax), version 2.1.3 and cqlsh version 5.0.1.

Cassandra starts up fine and the cluster is operational instantly.

Cqlsh is not working (on any of the nodes) and emits the following error:

&gt;Connection error: (&#39;Unable to connect to any servers&#39;, {&#39;127.0.0.1&#39;: error(111,
&quot;Tried connecting to [(&#39;127.0.0.1&#39;, 9042)]. Last error: Connection refused&quot;)})

I have tried starting cqlsh up with the hosts own ip, other hosts ip, different ports yet the result remains the same - always connection refused.

Content Type	Original Author	Original Content on Stackoverflow
Question	Chris H	View Question on Stackoverflow
Solution 1 - Cassandra	Richard	View Answer on Stackoverflow
Solution 2 - Cassandra	harish	View Answer on Stackoverflow

Inserting a hard-coded UUID via CQLsh (Cassandra)

Cassandra Problem Overview

Cassandra Solutions

Solution 1 - Cassandra

Solution 2 - Cassandra

UISearchBar text color change in iOS 7

How to remove one specific selected file from input file control

Attributions