Here is my problem:
I have many known locations (I have no influence to these) with a lot of data. Each locations offers me in individual periods of a lot new data. Some give me differential updates, some just the whole dataset, some via xml, for some I have to build a webscraper, some need authentication etc...
These collected data should be stored in a database. I have to program an api to send requested data in xml back.
Many roads lead to Rome but which should i choose?
Which software would you suggest me to use?
I am familiar with C++,C#,Java,PHP,MySQL,JS but new stuff is still ok.
My idea is to use cron jobs + php (or shell script) + curl to fetch the data.
Then I need a module to parse and insert the data into a database (mysql).
The data requests from clients could answer a php script.
I think the input data volume is about 1-5GB/day.
The one correct answer doesn't exist, but can you give me some advice?
It would be great if you can show me smarter ways to do this.
Thank you very much :-)
LAMP: Stick to PHP and MySQL (and make occasional forays into perl/python): availability of PHP libraries, storage solutions, scalability and API solutions and its community size well makes up for any other environment offerings.
API: Ensure that the designed API queries (and storage/database) can meet all end-product needs before you get to writing any importers. Date ranges, tagging, special cases.
PERFORMANCE: If you need lightning fast queries for insanely large data sets, sphinx-search can help. It's got more than just text search (tags, binary, etc) but make sure you spec the server requirements with more RAM.
IMPORTER: Make it modular: as in, for each different data source, write a pluggable importer that can be enabled/disabled by admin, and of course, individually tested. Pick a language and library based on what's best and easiest fit for the job: bash script is okay.
In terms of parsing libraries for PHP, there are many. One of recent popular ones is simplehtmldom and I found it to work quite well.
TRANSFORMER: Make data transformation routines modular as well so it can be written as a need arises. Don't make the importer alter original data, just make it the quickest way into an indexed database. Transformation routines (or later plugins) should be combined with API query for whatever end result.
TIMING: There is nothing wrong with cron executions, as long as they don't become runaway or cause your input sources to start throttling or blocking you so you need that awareness.
VERSIONING: Design the database, imports, etc to where errant data can be rolled back easily by an admin.
Vendor Solution: Check out scraperwiki - they've made a business out of scraping tools and data storage.
Hope this helps. Out of curiosity, any project details to volunteer? A colleague of mine is interested in exchanging notes.
Related
I want to make a detailed logger for my application and because it can get very complex and have to save a lot of different things I wonder where is the best to save it in a database(and if database wich kind of database is better for this kind of opperations) or in file(and if file what kind of format:text,csv,json,xml).My first thought was of course file because in database I see a lot of problems but I also want to be able to show those logs and for this is easier with database.
I am building a log for HIPPA compliance and here is my rough implementation (not finished yet).
File VS. DB
I use a database table to store the last 3 months of data. Every night a cron will run and push the older data (data past 3 months) off into compressed files. I haven't written this script yet but it should not be difficult. That way the last 3 months can be searched, filtered, etc. But the database won't be overwhelmed with log entries.
Database Preference
I am using MSSQL because I don't have a choice. I usually prefer MySQL though as it has better pager optimization. If you are doing more than a very minimal amount of searching and filtering or if you are concerned about performance you may want to consider an apache solr middle man. I'm not a db expert so I can't give you much more than that.
Table Structure
My table is 5 columns. Date, Operation (create, update, delete), Object (patient, appointment, doctor), ObjectID, and Diff (a serialized array of before and after values, changed values only no empty or unchanged values for the sake of saving space).
Summary
The most important piece to consider is: Do you need people to be able to access and filter/search the data regularly? IF yes consider a database for the recent history or the most important data.
If no a file is probably a better option.
My hybrid solution is also worth considering. I'll be pushing the files off to a amz file server so it doesn't take up my web servers space.
You can create the detail & Complex logger with using the some existing libraries like log4php because that is fully tested as part of the performance compare to you design custom for your self and it will also save time of development, I personally used few libraries from php and dotnet for our complex logger need in some financial and medical domain projects
here i would suggest if you need to do from the php then use this
https://logging.apache.org/log4php/
I think the right answer is actually: Neither.
Neither the file or a DB give you proper search, filtering, and you need that when looking at logs. I deal with logs all day long (see http://sematext.com/logsene to see why), and I'd tackle this as follows:
log to file
use a lightweight log shipper (e.g. Logagent or Filebeat)
index logs into either your own Elasticsearch cluster (if you don't mind managing and learning) or one of the Cloud log management services (if you don't want to deal with Elasticsearch management, scaling, etc. -- Logsene, Loggly, Logentries...)
I am in the planning stages of writing a CMS for my company. I find myself having to make the choice between saving page contents in a database or in folders on a file system. I have learned that PHP performs admirably well reading and writing to file systems, way better in fact than running SQL queries. But when it comes to saving pages and their data on a file system, there'll be a lot more involved than just reading and writing. Since pages will be drawn using a PHP class, the data for each page will be just data, no HTML. Therefore a parser for the files would have to be written. Also I doubt that all the data from a page will be saved in just one file, it would rather be saved in one directory, with content boxes and data in separated files.
All this would be done so much easier with MySQL, so what I want to ask you experts:
Will all the extra dilly dally with file system saving outweigh it's speed and resource advantage over MySQL?
Thanks for your time.
Go for MySQL. I'd say the only time you should think about using the file system is when you are storing files (BLOBS) of several megabytes, databases (at least the ones you typically use with a php website) are generally less performant when storing that kind of data. For the rest I'd say: always use a relational database. (Assuming you are dealing with data dat has relations of course, if it is random data there is not much benefit in using a relational database ;-)
Addition: If you define your own file-structure, and even your own way of cross referencing files you've already started building a 'database' yourself, that is not bad in itself -- it might be loads of fun! -- but you probably will not get the performance benefits you're looking for unless your situation is radically different than the other 80% of 'standard' websites on the web (a couple of pages with text and images on them). (If you are building google/youtube/flickr/facebook ... you've got a different situation and developing your own unique storage solution starts making sense)
things to consider
race-condition in file write if two user editing same piece of content
distribute file across multiple servers if CMS growth, latency on replication will cause data integrity problem
search performance, grep on files on multiple directory will be very slow
too many files in same directory will cause server performance especially in windows
Assuming you have a low-traffic, single-server environment here…
If you expect to ever have to manage those entries outside of the CMS, my opinion is that it's much, much easier to do so with existing tools than with database access tools.
For example, there's huge value in being able to use awk, grep, sed, sort, uniq, etc. on textual data. Proxying that through a database makes this hard but not impossible.
Of course, this is just opinion based on experience.
S
Storing Data on the filesystem may be faster for large blobs that are always accessed as one piece of information. When implementing a CMS, you typically don't only have to deal with such blobs but also with structured information that has internal references (like content fields belonging to a certain page that has links to other pages...). SQL-Databases provide an easy way to access structured information, files on your filesystem do not (except of course simple hierarchical structures that can be represented with folders).
So if you wanted to store the structured data of your cms in files, you'd have to use a file format that allows you to save the internal references of your data, e.g. XML. But that means that you would have to parse those files, which is not only a lot of work but also makes the process of accessing the data slow again.
In short, use MySQL
Use a database and you have lots of important properties from the beginning "for free" without inventing them in some suboptimal ways if you go the filesystem way. If you don't want to be constrained to MySQL only you can make use of e.g. the database abstraction layer of the doctrine project.
Additionally you have tools like phpMyAdmin for easy lookup or manipulation of your data versus the texteditor.
Keep in mind that the result of your database queries can almost always be cached in memory or even in the filesystem so you have the benefit of easier management with well known tools and similar performance.
When it comes to minor modifications of website contents (eg. fixing a typo or updating external links), I find it much easier to connect to the server using SSH and use various tools (text editors, grep etc.) on files, rather than I having to use CMS interface to update each file manually (our CMS has such interface).
Yet there are several questions to analyze and answer, mentioned above - do you plan for scalability, concurrent modification of data etc.
No, it will not be worth it.
And there is no advantage to using the filesystem over a database unless you are the only user on the system (in which the advantage would be lost anyway). As soon as the transactions start rolling in and updates cascades to multiple pages and multiple files you will regret that you didn't used the database from the beginning :)
If you are set on using caching, experiment with some of the existing frameworks first. You will learn a lot from it. Maybe you can steal an idea or two for your CMS?
I'm planning a PHP website architecture. It will be a small website with few visitors and small set of data. The data is modified exclusively by a single user (administrator).
To make things easier, I don't want to bother with a real database or XML data. I think about storing all data through PHP serialization into several files. So for example if there are several categories, I will store an array containing Category class instances for each category.
Are there any pitfalls using PHP serialization in those circumstances?
Use databases -- it is not that difficult and any extra time spent will be well learnt with database use.
The pitfalls I see are as Yehonatan mentioned:
1. Maintenance and adding functionality.
2. No easy way to query or look at data.
3. Very insecure -- take a look at "hackthissite.org". A lot of the beginning examples have to do with hacking where someone put the data hard coded in files.
4. Serialization will work for one array, meaning one table. If you have to do anything like have parent categories that have to match up to other data, not going to work so well.
The pitfalls come when with maintenance and adding functionality.
it is a very good way to learn but you will appreciate databases more after the lessons.
I tried to implement PHP serialization to store website data. For those who want to do the same thing, here's a feedback from the project started a few months ago and heavily modified since:
Pros:
It was very easy to load and save data. I don't have to write SQL queries, optimize them, etc. The code is shorter (with parametrized SQL queries, it may grow a lot).
The deployment does not require additional effort. We don't care about what is supported on the web server: if there is just PHP with no additional extensions, database servers, etc., the website will still work. Sqlite is a good thing, but it is not possible to install it on some servers, and it also requires a PHP extension.
We don't have to care about updating a database server, nor about the database server to use (thus avoiding the scenario where the customer wants to migrate from Microsoft SQL Server to Oracle, etc.).
We can add more properties to the objects without having to break everything (just like we can add other columns to the database).
Cons:
Like Kerry said in his answer, there is "no easy way to query or look at data". It means that any business intelligence/statistics cases are impossible or require a huge amount of work. By the way, some basic scenarios become extremely complicated. Let's say we store products and we want to know how much products there are. Instead of just writing select count(1) from Products, in my case it requires to create a PHP file just for that, load all data then count the number of items, sometimes by adding stuff manually.
Some changes required to implement data migration, which was painful and required more work than just executing an SQL query.
To conclude, I would recommend using PHP serialization for storing data of a small website modified by a single person only if all the following conditions are true:
The deployment context is unknown and there are chances to have a server which supports only basic PHP with no extensions,
Nobody cares about business intelligence or similar usages of the information,
There will be no changes to the requirements with large impact on the data structure.
I would say use a small database like sqlite if you don't want to go through setting up a full db server. However I will also say that serializing an array and storing that in a text file is pretty dang fast. I've had to serialize an array with a few thousand records (a dump from a database) and used that as a temp database when our DB server was being rebuilt for a few days.
For a very large site such as a Social Network (say Facebook), which method would you recommend for user accounts storage?
1) Single XML files for each type of features, on the user's directory: basicinfo.xml, comments.xml, photos.xml, ...
2) MySQL, although not sure how to organize on this. Maybe separated tables for each feature? E.g. a tables for Comments, where columns are id,from,message,time?
I know XML is not designed for storage, and PHP (this is the language I use) must read the entire XML file and store in memory before it is used.
But, here are the reasons why I prefer XML (but I may be wrong, please tell me if you disagree with any):
1) If I have user accounts' paths organized in this way
User ID 2342:
/users/00/00/00/00/00/00/00/23/42/
I think it's faster to find the Comments of a user by file path than seeking in a large database.
Also, if each feature is split in tables, each user profile will seek more than once, to display comments, photos, basic info, etc.
2) I heard MySQL is globaly locked when writing on it. Is this true? If yes, I rather to lock a single file than everything.
3) Is MySQL "shared" between the cluster? I mean, if 1 disk gets full, will it "continue" on another? Or do I, as the programmer, have to manage it myself and create new databases on another disk? (note, I use Linux)
It is ok that it is about the same by using XML files, but it is easier to split between disks, because structure is split by account IDs, not by feature as it would be in a database.
4) Note that I don't store each comment on the comments.xml. I just note their attributes in each XML tag, and the messages are in separated text files commentid.txt. Once each XML should not be much large, there should not be problems with memory/time.
As for the problem of parsing entire XML, maybe I should think on using XMLReader/Writer instead of SimpleXML/DOM? Or, will it decrease performance allot?
Thank you!
Facebook uses MySQL.
That being said. Here's the long version:
I always say that XML is a data transfer technology, not a data storage technology, but not everyone agrees. XML is not designed to be use a relational datastore. XML was first introduced in order to provide a standard way of transmitting data from system to system w/o giving access to the originating systems.
Since you are talking about a large application, I would strongly urge you to use MySQL (or other RDBMS), as your dataset grows and grows the XML will be increasingly slower and slower unless you always keep a fresh copy in memory and only read the XML files upon service reboot.
Using an XML database is reportedly more efficient in terms of conversion costs when you're constantly sending XML into and retrieving XML out of a database. The rationale is, when XML is the only transport syntax used to get things in and out of the DB, why squeeze everything through a layer of SQL abstraction and all those relational tables, foreign keys, and the like? It basically takes a parsing layer out of the application and brings it into the data engine - where it's probably going to work faster and more efficiently than the SQL alternative. Probably.
Depends heavily on the nature of your site. On the one hand the XML approach gives you a free pass on things like “SELECT * FROM $table where $table.id=$id” type queries. On the other hand...
For a very large site, in the worst case scenario the data files end up pretty big too. If it is any kind of community site this may easily happen for any account go to any forum with a true number of old-guard members in its community and you'll find a couple of posters that have say 10K posts... This means you will wish for SQL style result sets which are implemented using a memory efficient model, rather than a speed efficient one. To the end user 1s versus 1.1s response time is not that much of a deal; but to you 1K of simultaneous requests versus 1.5K or better definitely is.
Then there is the aspect that if you are mostly reading data XML may be fine if somewhat crude for large data sets and DOM based implementations. But if you are writing a lot, things become much much worse. Caching of data is still possible, but giving ACID like guarantees on these file transactions requires you to pretty much write your own database software.
And then there is storage requirements and such like which mean you may need a distributed approach for storing your data. These kind of setups are relatively well understood in the database world, and they bring a lot of interesting problems with them to the table (like what do you do if a single disk fails?, how do you know on what disk to find the data and how do you implement efficient caching?) that essentially amount to again writing your own mini-database software from scratch.
So for a very large site I think the hard technical requirements of performance at not too great a cost in terms of memory and also a certain reliability and not needing to reinvent 21 wheels at the same time means that your approach would not work that well. I think it is better suited to smallish read-only sites where you can afford to experiment with and pursue alternative routes, where you can easily make changes and roll them out across the entire site.
IME: An in-house application using a single XML file for persistence didn't stand up to use by a single user...
1) What you're suggesting is that an XML file system with a manager application... There are XML databases, and XML there's been increasing support for storing XML within RDBMS. You're looking at re-inventing the wheel...
That's besides the normalization that would come out of storing the data in a RDBMS, which would enforce referential integrity that XML will never do...
2) "Global locking" is without any contextual scope. No database I know of locks globally when writing; most support degrees of locking (table/row/etc, varies between vendors) for sake of retaining concurrency when directed to - not by default.
3) Without a database, data or actual users--being concerned about clustering is definitely premature optimization.
4) If the system crashes without having written the referential integrity to some sort of persistence that will survive the application being turned off, the data will be useless.
I'm creating and app that will rely on a database, and I have all intention on using a flat file db, is there any serious reasons to stay away from this?
I'm using mimesis (http://mimesis.110mb.com)
it's simpler than using mySQL, which I have to admit I have little experience with.
I'm wondering about the security of the db. but the files are stored as php and it seems to be a solid database solution.
I really like the ease of backing up and transporting the databases, which I have found harder with mySQL. I see that everyone seems to prefer the mySQL way - and it likely is faster when it comes to queries but other than that is there any reason to stay away from flat-file dbs and (finally) properly learn mysql ?
edit
Just to let people know,
I ended up going with mySQL, and am using the CodeIgniter framework. Still like the flat file db, but have now realized that it's way more complex for this project than necessary.
Use SQLite, you get a database with many SQL features and yet it's only a single file.
Greetings, I'm the creator of Mimesis. Relational databases and SQL are important in situations where you have massive amounts of data that needs to be handled. Are flat files superior to relation databases? Well, you could ask Google, as their entire archiving system works with flat files, and its the most popular search engine on Earth. Does Mimesis compare to their system? Likely not.
Mimesis was created to solve a particular niche problem. I only use free websites for my online endeavors. Plenty of free sites offer the ability to use PHP. However, they don't provide free SQL database access. Therefore, I needed to create a database that would store data, implement locking, and work around file permissions. These were the primary design parameters of Mimesis, and it succeeds on all of those.
If you need an idea of Mimesis's speed, if you navigate to the first page it will tell you what country you're viewing the site from. This free database is taken from the site ip2nation.com and ported into a Mimesis ffdb. It has hundreds if not thousands of entries.
Furthermore, the hit counter on the main page has already tracked over 7000 visitors. These are UNIQUE visits, which means that the script has to search the database to see if the IP address that's visiting already exists, and also performs a count of the total IPs.
If you've noticed the main page loads up pretty quickly and it has two fairly intensive Mimesis database scripts running on the backend. The way Mimesis stores data is done to speed up read and write procedures and also translation procedures. Most ffdb example scripts or other ffdb scripts out there use a simple CVS file or other some such structure for storing data. Mimesis actually interprets binary data at some levels to augment its functionality. Mimesis is somewhat of a hybrid between a flat file database and a relational database.
Most other ffdb scripts involve rewriting the COMPLETE file every time an update is made. Mimesis does not do this, it rewrites only the structural file and updates the actual row contents. So that even if an error does occur you only lose new data that's added, not any of the older data. Mimesis also maintains its history. Unless the table is refreshed the data that rows had previously is still contained within.
I could keep going on about all the features, but this isn't intended as a "Mimesis is the greatest database ever" rant. Moreso, its intended to open people's eyes to the fact that SQL isn't the ONLY technology available, and that flat files, when given proper development paradigms are superior to a relational database, taking into account they are more specialized.
Long live flat files and the coders who brave the headaches that follow.
The answer is "Fine" if you only NEED a flat-file structure. One test: Would a single simple spreadsheet handle all needs? If not, you need a relational structure, not a flat file.
If you're not sure, perhaps you can start flat-file. SQLite is a great app for getting started.
It's not good to learn you made the wrong choice, if you figure it out too far along in the process. But if you understand the importance of a relational structure, and upsize early on if needed, then you are fine.
I really like the ease of backing up
and transporting the databases, which
I have found harder with mySQL.
Use SQLite as mentioned in another answer. There is only one file to backup, or set up periodic dumps of the MySQL databases to SQL files. This is a relatively simple thing to do.
I see that everyone seems to prefer
the mySQL way - and it likely is
faster when it comes to queries
Speed is definitely a consideration. Databases tend to be a lot faster, because the data is organized better.
other than that is there any reason to
stay away from flat-file dbs and
(finally) properly learn mysql ?
There sure are plenty of reasons to use a database solution, but there are arguments to be made for flat files. It is always good to learn things other than what you "usually" use.
Most decisions depend on the application. How many concurrent users are you going to have? Do you need transaction support?
Wanted to inform that Mimesis has moved from the original URL to http://mimesis.site11.com/
Furthermore, I am shifting the focus of Mimesis from an ffdb to a key-value store. It's more sensible Given the types of information I'm storing and the methods I use to retrieve it. There was also a grave error present in the coding of Mimesis (which I've since fixed). However, I'm still in the testing phase of the new key-value store type. I've also been side-tracked by other things. Locking has also been changed from the use of file creation to directory creation as the mutex mechanism.
Interoperability. MySQL can be interfaced by basically any language that counts. Mimesis is unlikely to be usable outside PHP.
This becomes significant the moment you try to use profilers, or modify data from the outside.
You might also look at http://lukeplant.me.uk/resources/flatfile/ for the PHP Flatfile Package.
The issue with going flatfile is that in order to adjust the situation for further development you have to alter a significant amount of code in order to improve the foundation of the system. Whereas if it was a pure SQL system it would require little to no modification to proceed in the future.