In order to check the filesystem of the partition and where that partition maps to that address use:

mount -l

It will show for example that you have a partition that mounted by NFS or that a partition is ext4 and so on:

/dev/mapper/vg-var on /var type ext4 (rw,relatime,stripe=384,data=ordered)

#linux #mount #ext4 #nfs #filesystem #partition

For optimal performance in terms of the storage layer, use disks backed by RAID-10. RAID-5 and RAID-6 do not typically provide sufficient performance to support a MongoDB deployment.

Avoid RAID-0 with MongoDB deployments. While RAID-0 provides good write performance, it also provides limited availability and can lead to reduced performance on read operations, particularly when using Amazon’s EBS volumes.


#mongodb #mongo #disk #raid #SSD

How to detect unused indexes on MongoDB collections?

db.your_collection.aggregate([{$indexStats:{}}]).pretty()

ops displays operations per second on a specific index. If ops is very low compared to other indexes you can drop the index.

#mongodb #mongo #index #unused_indexes

#mongodb #backlog #road_map

The good news is MongoDB will support transactions from version 4.0 like any other DBMS systems like MySQL, Oracle,...

Scaling MongoDB - Avoiding Common Pitfalls

#mongodb #video #tutorial

Looks like they need to defrag the port.

OnePHP a super simple and super lightweight PHP framework that works in just a few lines:

// index.php
 require_once('src/OnePHP/one_framework.php');
 $app = new \OnePHP\App();

 $app->get('/:name',function( $name ) use ( $app ){//Action
   echo "Hello $name";
 });
 $app->listen();

To install using composer:

composer create-project julces/oneframework

Why OnePHP:

1- Restful Routes

2- Easy and clean (GET, POST, PUT, DELETE...) Requests management

3- Restful Response with HTTP Status Code and custom Headers

4- PHP native Views

5- No dependencies, add extra libraries only when you need it.

#php #framework #onePHP

If you have a dedicated server only for MongoDB database I would I highly recommend to set block size as mongo suggested for their engines.


For the WiredTiger storage engine:

Set the readahead setting to 0 regardless of storage media type (spinning, SSD, etc.).

Setting a higher readahead benefits sequential I/O operations. However, since MongoDB disk access patterns are generally random, setting a higher readahead provides limited benefit or performance degradation. As such, for most workloads, a readahead of 0 provides optimal MongoDB performance.

In general, set the readahead setting to 0 unless testing shows a measurable, repeatable, and reliable benefit in a higher readahead value. MongoDB Professional Support can provide advice and guidance on non-zero readahead configurations.


For the MMAPv1 storage engine:

Ensure that readahead settings for the block devices that store the database files are appropriate. For random access use patterns, set low readahead values. A readahead of 32 (16 kB) often works well.

For a standard block device, you can run sudo blockdev --report to get the readahead settings and sudo blockdev --setra <value> <device> to change the readahead settings. Refer to your specific operating system manual for more information.


#mongodb #mongo #ra #readahead #mmapv1 #wiredtiger

In python in order to swap variables you can use unpack feature:

>>> a, b = 1, 2
 >>> a, b = b, a
 >>> a, b
 (2, 1)

This is a nice way to swap variables without using a third variable.

#python #swap #swap_variables

Extended unpacking (`Python 3 Only`):

>>> a, *b, c = [1, 2, 3, 4, 5]
 >>> a
 1
 >>> b
 [2, 3, 4]
 >>> c
 5

This way first and last list element will be unpacked into a and c and other values will be inside of b variable.

#python #python3 #unpack #extended_unpack

Learn the Zen of Python:

>>> import this
 The Zen of Python, by Tim Peters

 Beautiful is better than ugly.
 Explicit is better than implicit.
 Simple is better than complex.
 Complex is better than complicated.
 Flat is better than nested.
 Sparse is better than dense.
 Readability counts.
 Special cases aren't special enough to break the rules.
 Although practicality beats purity.
 Errors should never pass silently.
 Unless explicitly silenced.
 In the face of ambiguity, refuse the temptation to guess.
 There should be one-- and preferably only one --obvious way to do it.
 Although that way may not be obvious at first unless you're Dutch.
 Now is better than never.
 Although never is often better than *right* now.
 If the implementation is hard to explain, it's a bad idea.
 If the implementation is easy to explain, it may be a good idea.
 Namespaces are one honking great idea -- let's do more of those!

By importing this in your python console you will get the zen of python as above. :)

#python #this #zen_of_python #zen

Click is a Python package for creating beautiful command line interfaces in a composable way with as little code as necessary. It’s the “Command Line Interface Creation Kit”. It’s highly configurable but comes with sensible defaults out of the box.

- http://click.pocoo.org/6/

#python #argparse #click #command_line_interface

Backup and Restor from couchDB

- https://github.com/danielebailo/couchdb-dump


#database #couchdb #couch #couchBase #backup

Format a volume as XFS in Debian


First of all install xfsprogs:

apt-get install xfsprogs

Make sure your formatting a right drive! Use ls to list drives:

root@debian:~# ls /dev/sd*
 /dev/sda  /dev/sda1  /dev/sda2  /dev/sda5  /dev/sdb  /dev/sdb1  /dev/sdc

In this installation I will format the drive /sdc, I know this because this is a blank drive with no partitions.

Now we partition the drive with the help of fdisk. fdisk can be scary if you have never used it before, in order to partition the drive use the commands below. Note: this will create one big partition, use the values inside the brackets [] as a guide.

root@debian:~# fdisk /dev/sdb

 Command (m for help): [n]
 Partition type:
    p   primary (0 primary, 0 extended, 4 free)
    e   extended
 Select (default p): [p]
 Partition number (1-4, default 1): [1]
 First sector (2048-335544319, default 2048): [press Enter]
 Using default value 2048
 Last sector, +sectors or +size{K,M,G} (2048-335544319, default 335544319): [press Enter]
 Using default value 335544319

 Command (m for help): [w]
 The partition table has been altered!

 Calling ioctl() to re-read partition table.
 Syncing disks.

Because we installed xfsprogs we can make use of mkfs.xfs to format the partition we created in the step above. -L will label the drive as media:

root@debian:~# mkfs.xfs -L media /dev/sdc1

Create a mount point:

root@debian:/dev# mkdir /mnt/dat1

Mount the drive:

root@debian:~# mount -t xfs /dev/sdc1 /mnt/dat1

Let’s check the newly mounted volume, visible at the bottom:

root@debian:/dev# df -h

 Filesystem      Size  Used Avail Use% Mounted on
 /dev/sda1        50G  1.9G   46G   4% /
 udev             80M  4.0K   80M   1% /dev
 tmpfs            36M  272K   35M   1% /run
 none            5.0M     0  5.0M   0% /run/lock
 none             88M     0   88M   0% /run/shm
 /dev/sdc1       160G   33M  160G   1% /mnt/dat1

To permanently mount the new volume every time the system boots you will need to edit and add a new entry to /etc/ fstab. You can use the echo command to easily add the new entry:

root@debian:# echo '/dev/sdc1 /mnt/dat1 xfs defaults 0 0' >> /etc/fstab

Or manually add the entry below to fstab with the text editor of your choice:

/dev/sdc1 /mnt/dat1 xfs defaults 0 0

XFS is a good file system for those of us working with large files. This is a recommended filesystem for those working with MongoDB wiredTiger too.

#linux #filesystem #xfs #fdisk #mount #df #fstab #xfsprogs #mkfs_xfs

#ebook #book #epub #microservice

Today I had to migrate the ODM class from CouchDB to MongoDB for a specific module. As we didn't combine logic into our backend database we easily changed db to MongoDB.

Go take a look at your code see whether you can change the backend DB easily from your current database to another database? Will you scratch your head when CTO says, ok we are moving to BlahDB, what would you do? How much flexibilty you have?

Some people may argue that we don't change backend DB that much and we do not ever change the backend DB! This a naive consideration and I would highly recommend to think over. Because this code change flexibility shows how well your structure is implemented. How well you have programmed.

#couchdb #mongodb