I can talk about Icinga2 for about a book! From memory, CPU, disk usage monitoring to even creating custom plugins with python or other languages to monitor your specific use case (Let's you want to monitor your microservice modules).

Maybe in the future I do so! :)

One of the greatest examples of Geospatial queries is MongoDB's tutorial about finding the nearest restaurant. This example can be applied to online taxis like Snapp, tap30 or some social networks. Read the below article if you are crazy as hell to learn new things like me :)


https://docs.mongodb.com/manual/tutorial/geospatial-tutorial/

#mongodb #mongo #geospatial #geoWithin #geoNear #geo #2dsphere #geoIntersects

در طول دوره کاری خود بارها با بحث تغییر نیازمندیهای بیزینس مواجه شده ام و در تمامی موارد به جرات می توانم بگویم که هر زمانی که تغییر نیازمندی باعث تغییر زیاد در ماژولها میشود و من از انجام تغییر از راه میانبر و به قولی کثیف پیش برده ام یکجا همون قضیه یقه من راه گرفته (bite in the ass) و هر بار که تغییر مورد نظر با اینکه زیاد هم بوده انجامش داده ام توانستم که به بهترین نحو مسئله را حل کنم و در آینده هم خودم از کارم راضی بودم.

نکته مهم قضیه این هست که همیشه مدیران عامل به سریعترین وجه ممکن خروجی را از شما میخواهند، در این گونه مواقع سریع تسلیم نشوید و کار کثیف و میانبر که بد هست را انجام ندهید. مدیر عامل فردی ست مثل شما با آنها صحبت کنید و بگویید به این دلایل زمان بیشتری میخواهید و باید به این صورت انجام شود وگرنه در آینده به مشکل میخوریم، در اکثر موارد موفق می شوید که زمان بیشتری بخرید و کار را بصورت درست انجام دهید. در کنار زمان، این مسئله به اخلاق برنامه نویسی نیز بازمیگردد و برخی افراد حوصله کار زیاد والبته درست را ندارند!!! عجیب است ولی خود من هم تا چند سال پیش در همین دسته جای میگرفتم.

نکته اینجاست که اخلاقتون رو خوب کنید :)
و نکته بعد این هست که با مدیران خود صحبت کنید و آنها را در قبال کاری که میکنید توجیح کنید.

#دلنوشته

https://medium.com/@psamim/performance-tips-to-have-in-mind-while-writing-react-components-1f387adce7a5

#react #reactjs

https://askubuntu.com/questions/919054/how-do-i-run-a-single-command-at-startup-using-systemd

#linux #systemd #systemctl #service

Upgrade mongoDB from 3.4 to 3.6:

Here we persume you are on debian 8 jessie.

1- import public key:

sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv                        2930ADAE8CAF5059EE73BB4B58712A2291FA4AD5

2- create apt sources file:

echo "deb http://repo.mongodb.org/apt/debian jessie/mongodb-org/3.6 main" | sudo tee /   etc/apt/sources.list.d/mongodb-org-3.6.list

3- update repo

sudo apt-get update

4- install the MongoDB packages

sudo apt-get install -y mongodb-org=3.6.2 mongodb-org-server=3.6.2 mongodb-org-shell=3.  6.2 mongodb-org-mongos=3.6.2 mongodb-org-tools=3.6.2

* it will ask for config overwrite, if you want to take backup take a backup from config and then overwrite it.


#mongodb #mongo #mongodb36 #database #upgrade #mongodb34

Read on more: https://docs.mongodb.com/manual/tutorial/install-mongodb-on-debian/

Check grants of a specific user on MySQL:

SELECT sql_grants FROM common_schema.sql_show_grants WHERE user='app';

Please make sure that you have permissions on getting grants list, otherwise permission denied will be returned back.

#mysql #grants #sql_grants #database

Did you know that the mongoDB shell is a full-featured JavaScript interpreter, capable of running arbitrary JavaScript programs? To illustrate this, let’s perform some basic math:

> x = 200
 200
 > x / 5;
 40

We can also leverage all of the standard JavaScript libraries:

> Math.sin(Math.PI / 2);
 1
 > new Date("2010/1/1");
 "Fri Jan 01 2010 00:00:00 GMT-0500 (EST)"
 > "Hello, World!".replace("World", "MongoDB"); Hello, MongoDB!

We can even define and call JavaScript functions. In previous posts we explained how to kill slow queries, there we explained how to define a function in MongoDB and store that function inside of MongoDB.


#mongodb #mongo #shell #javascript #js

You can read more about mongoDB functions here...

OperationalError: (2013, 'Lost connection to MySQL server during query')

Usually it indicates network connectivity trouble and you should check the condition of your network if this error occurs frequently. If the error message includes “during query,” this is probably the case you are experiencing.

Sometimes the “during query” form happens when millions of rows are being sent as part of one or more queries. If you know that this is happening, you should try increasing net_read_timeout from its default of 30 seconds to 60 seconds or longer, sufficient for the data transfer to complete.

More rarely, it can happen when the client is attempting the initial connection to the server. In this case, if your connect_timeout value is set to only a few seconds, you may be able to resolve the problem by increasing it to ten seconds, perhaps more if you have a very long distance or slow connection. You can determine whether you are experiencing this more uncommon cause by using SHOW GLOBAL STATUS LIKE 'Aborted_connects'. It will increase by one for each initial connection attempt that the server aborts. You may see “reading authorization packet” as part of the error message; if so, that also suggests that this is the solution that you need.

If the cause is none of those just described, you may be experiencing a problem with BLOB values that are larger than max_allowed_packet, which can cause this error with some clients. Sometime you may see an ER_NET_PACKET_TOO_LARGE error, and that confirms that you need to increase max_allowed_packet.

#database #mysql #OperationalError #connection

How to check MySQL version:

If you have local access to mySQL server you can check it by:

mysql -v

If you have remote access to MySQL you can first login to mysql using mysql -u USERNAME -p PASS -h REMOTE_HOST. And then after successful login issue the below command:

SELECT version();

#mysql #version

#programmer_jokes #fun

To get time in epoch in linux`/`OS X you can use date with formatting like below:

date +%s

The output of the command is similar to the following output:

1518517636

#linux #osx #date #epoch

دوستانی که در مورد تدریس خصوصی سوال کرده بودند، خدمتشون عارض هستم که تا آخر سال متاسفانه فرصتش وجود نداره و کمی برای آخر سال سرمون شلوغ هستش. ان شالله بعد از عید در صورتی که فشار کاری کمتر بشه خدمتتون میگم. ممنونم بابت پیام های امید بخشتون برای ادامه کار. 💐

#تدریس #خصوصی

In order to connect directly to MongoDB from your host:

mongo YOUR_REMOTE_MONGO_SERVER:27017

If your MongoDB port is different, use your desired port rather than 27017.


The interesting thing about this command is that you can give database name that you want to work on:

mongo YOUR_REMOTE_MONGO_SERVER:27017/YOUR_DB

Now after connecting if you use db command you should see your current db:

rs0:PRIMARY> db
 YOUR_DB

rs0:PRIMARY will be shown when you use replication. Your case may be different.

#database #mongodb #mongo

How to print a sentence when users on the server run mongo shell?

For DBAs to limit some dangerous functionalities like dropping a database or it can be a helpful message. Or a greeting message. Or even printing the default database that he is already connected to.

By default mongoDB looks for a file named .mongorc.js in your home directory. So create a file ~/.mongorc.js and put a content like below inside of it:

print("Hello! Welcome to Alireza company :)");
 print("Your database is set to: " + db);

That's it! Save the file and run mongo in your terminal, the output should be similar to the following:

$ mongo
 MongoDB shell version v3.6.2
 connecting to: mongodb://127.0.0.1:27017
 MongoDB server version: 3.6.2
 Your database is set to: test
 Hello! Welcome to Alireza company :)
 >

In order to disable dangerous functionalities:

var no = function() { print("oops! You are not allowed to drop anything!!");};

 // Prevent dropping databases
 db.dropDatabase = DB.prototype.dropDatabase = no;

 // Prevent dropping collections
 DBCollection.prototype.drop =no;

 // Prevent dropping indexes
 DBCollection.prototype.dropIndex = no;

Sample output:

> db.dropDatabase('bi')
 oops! You are not allowed to drop anything!!.

NOTE: You can disable loading your .mongorc.js by using the --norc option when starting the shell.

#mongodb #mongo #shell #mongorc

#Google on #valentine.

In order to connect to MongoDB replica set in Python you can give all server node addersses to MongoClient. Addresses passed to MongoClient() are called the seeds. As long as at least one of the seeds is online, MongoClient discovers all the members in the replica set, and determines which is the current primary and which are secondaries or arbiters.


Sample usages:

>>> MongoClient('localhost', replicaset='foo')
     MongoClient(host=['localhost:27017'], replicaset='foo', ...)
 >>> MongoClient('localhost:27018', replicaset='foo')
     MongoClient(['localhost:27018'], replicaset='foo', ...)
 >>> MongoClient('localhost', 27019, replicaset='foo')
     MongoClient(['localhost:27019'], replicaset='foo', ...)
 >>> MongoClient('mongodb://localhost:27017,localhost:27018/?replicaSet=foo')
     MongoClient(['localhost:27017', 'localhost:27018'], replicaset='foo', ...)

Read full details here:

- http://api.mongodb.com/python/current/examples/high_availability.html#connecting-to-a-replica-set


#database #mongodb #mongo #replica_set #replication #pymongo #arbiter #master #primary #slave

Secondary Reads

By default an instance of MongoClient sends queries to the primary member of the replica set. To use secondaries for queries we have to change the read preference:

>>> client = MongoClient(
 ...     'localhost:27017',
 ...     replicaSet='foo',
 ...     readPreference='secondaryPreferred')
 >>> client.read_preference
 SecondaryPreferred(tag_sets=None)

Now all queries will be sent to the secondary members of the set. If there are no secondary members the primary will be used as a fallback. If you have queries you would prefer to never send to the primary you can specify that using the secondary read preference.

#mongodb #replica_set #replication #secondary #slave #pymongo