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NoSQL Databases

127

Solutions

249

Contributors

A NoSQL database provides a mechanism for storage and retrieval of data which is modeled in means other than the tabular relations used in relational databases. Motivations for this approach include: simplicity of design, simpler "horizontal" scaling to clusters of machines and finer control over availability. The data structures used by NoSQL databases (e.g. key-value, wide column, graph, or document) are specified from those used by default in relational databases, making some operations faster in NoSQL. Sometimes the data structures used by NoSQL databases are also viewed as "more flexible" than relational database tables.

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I've been thinking to migrate my erp(java currently) from rdbms(firebird currently) to nosql (mongoDB likely) and i trying to antecipate some issues. I'm trying to make a "failproof" inventory control which never let a qty's item be smaller than 0. Offcourse i still get "ACID bias" which i need to left in order to complete this task. The goal is update inventory qty of all order's items when approve the order. For that, 2 problems can occur which currently are resolved with a trigger.

1.problem: order gets 2 items (ball = qty 2 and chair = qty 1) and there is no enough qty in inventory (ball = qty 1 and chair = qty 0) to complete the order. Once i trigger the command do complete the order, a loop is executed to decrease qty in inventory and fails on the second item cause there is no enough qty. Consequently rollback operation is trigged and everybody go home happy.

2.problem: in one word, concurrency. suppose there is no trigger controling this operation but only "selects and if". User 1 query inventory qtys, see enough qty (ball = 2, chair = 1) e system allow complete the order. While the transaction is running user 2 query same invetory qtys but because first transaction is not complete yet second query see "old" qty (ball = 2, chair = 1) e system also lets complete order. Consequently, 1 qty of chair is descreased twice, but shold be descreased only once and fail on the second. Result: i got negative qty.

I saw some workarrounds with inventory reservation but i …
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hi,

any  tools/idea you all use to synchronization between traditional RDMS and NoSQL in MS SQL and maria DB and noSQL?
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Created a duplicate username entry in mongoose database and resulted in duplicated error. Now everytime I start server, I get this error:

(node:14839) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 1): CastError: Cast to ObjectId failed for value "{ type: 'Buffer',
  data: [ 89, 243, 30, 231, 66, 69, 45, 56, 123, 65, 153, 72 ] }" at path "_id" for model "users"
(node:14839) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.
0
I am trying to update a dict with values searched from mongoDB whose parameters are taken from another dict. What I have till now is:

    lst = {'a':1}
    b={'Name':'name_1', 'Address':'Address_1'}
    lst.update(k:coll.find({"_id":id}{v:1})) for k,v in b.items()

What is the right way to do this procedure?
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Hi, I have the following document and I want to delete all keys that are empty:

so it should delete the key year from first instance and build on second instance since is empty. I want the query to update all documents and clear that array of options of empty values.

{
    _id: 'sldkfjsldkf',
    name: "Red car",
    options: [
       {
          color: "red",
          year: "",
          build: "2000"
       },
       {
          color: "yellow",
          year: "1988",
          build: ""
       },
  ]

}
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I just installed ElasticSearch, MongoDB, GrayLog2 but getting an error and unable to access the web interface. Please, suggest any solution r

/etc/elasticsearch
# ls -lrtha
drwxr-x---.  2 root elasticsearch    6 Apr 24 16:29 scripts
-rwxr-x---.  1 root elasticsearch 2.6K Apr 24 16:04 logging.yml
-rwxr-x---.  1 root elasticsearch 3.2K Jul 20 05:05 elasticsearch.yml


/var/log/graylog-server/server.log

2017-07-20T07:50:36.694Z INFO  [CmdLineTool] Loaded plugin: Elastic Beats Input 2.2.3 [org.graylog.plugins.beats.BeatsInputPlugin]
2017-07-20T07:50:36.696Z INFO  [CmdLineTool] Loaded plugin: Collector 2.2.3 [org.graylog.plugins.collector.CollectorPlugin]
2017-07-20T07:50:36.699Z INFO  [CmdLineTool] Loaded plugin: Enterprise Integration Plugin 2.2.3 [org.graylog.plugins.enterprise_integration.EnterpriseIntegrationPlugin]
2017-07-20T07:50:36.700Z INFO  [CmdLineTool] Loaded plugin: MapWidgetPlugin 2.2.3 [org.graylog.plugins.map.MapWidgetPlugin]
2017-07-20T07:50:36.708Z INFO  [CmdLineTool] Loaded plugin: Pipeline Processor Plugin 2.2.3 [org.graylog.plugins.pipelineprocessor.ProcessorPlugin]
2017-07-20T07:50:36.709Z INFO  [CmdLineTool] Loaded plugin: Anonymous Usage Statistics 2.2.3 [org.graylog.plugins.usagestatistics.UsageStatsPlugin]
2017-07-20T07:50:36.813Z ERROR [CmdLineTool] Invalid configuration
com.github.joschi.jadconfig.ValidationException: Cannot read file elasticsearch_config_file at path /etc/elasticsearch/elasticsearch.yml. Please specify the correct …
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Hi,

Please bear with me, my Mongo knowledge is minimal and my google foo has failed me after an hour or two.

I have data in Mongo that looks as follows:

{
    "_id" : ObjectId("xxxx"),
    "applicationData" : {
        "groups" : [
            "group1",
                  "group2",
        ],
        "status" : "ok"
    },
    "appid" : "UID0001",
}

{
    "_id" : ObjectId("yyyy"),
    "applicationData" : {
        "groups" : [
                  "group2"
        ],
        "status" : "ok"
    },
    "appid" : "UID0001",
}

From this I'm wanting to group by the content of "groups" and the appid an get a count - the result would be as follows:

group1  UID0001 1
group2  UID0001 2

One step further would be that I'd only like it to report where the "count" is greater than 1

How can I achieve this?

I guess, in SQL, it would be:

select groups, appid, count(*) from db having count(*) > 1

I'm not having much (any) success, further complicated with one of the values I'm wanting to group by is in an Array.

Thanks in advance
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I am using php and mongoDb. I am new to mongoDb, but fine with php.  In my mongoDb database I have a  collection called 'users' with a number of fields such as firstname, lastname etc. There are a number of users.


I also have a field/collection in some users called web_links which contains an array.
ie: within my users document:
{
    "_id" : ObjectId("587af11ec09cf31a1955ed92"),
    "username" : "mike",
    "firstname" : "Mike",
    "lastname" : "Tester",
    "email" : "mike@test.com",
    "web_links" : [
        {
            "name" : "google",
            "link" : "https://google.com",
            "status" : "1",
            "added" : ISODate("1970-01-18T08:00:57.600Z")
        },
        {
            "name" : "yahoo",
            "link" : "https://yahoo.com",
            "status" : "1",
            "added" : ISODate("1970-01-18T08:00:57.600Z")
        }
    ]
}

I am trying to firstly update the status of an array item.
I have got as far as this ->

$name = 'google';
$newstatus = '0';

$this->database->users->updateOne(['_id'=>new MongoDB\BSON\ObjectId($userid)],['web_links.name'=>$name],['$set'=>['web_links.$.status'=>$newstatus]]);

This is returning the following error via firebug:
Uncaught exception 'MongoDB\Exception\InvalidArgumentException' with message 'First
 key in $update argument is not an update operator'.

I have tried to change $set to $push, but that is not the answer.

I would be very grateful for assistance …
0
Hi,

I would like to know how to ensure primary key in the dynamo db. is there is any way to do that,,, Any example which can
help us.

roy..
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Hello  ,

i'm new member here , so i say hi to everybody , i'm working on integration project of supervision ( monitoring ) . the Server is RHEL 6 & Redis server installed is 2.8 , redis server is running , but when i try to start my sensu server it generate a problem . "  unable to connect to redis server " in sensu-server log
0

NoSQL Databases

127

Solutions

249

Contributors

A NoSQL database provides a mechanism for storage and retrieval of data which is modeled in means other than the tabular relations used in relational databases. Motivations for this approach include: simplicity of design, simpler "horizontal" scaling to clusters of machines and finer control over availability. The data structures used by NoSQL databases (e.g. key-value, wide column, graph, or document) are specified from those used by default in relational databases, making some operations faster in NoSQL. Sometimes the data structures used by NoSQL databases are also viewed as "more flexible" than relational database tables.

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