I was asking the following question during interviewing in a company working on cloud computing, and did not answer well. Any suggestions on how to analyze this question will be greatly appreciate.
Our company has hundreds of millions of users and we expect zero down time in production, explain techniques and programming practices that help improve redundancy and fail-over capabilities for front-end, middle-tier and back-end services including database services.
This question is very much along the lines of the "Impossible Question" from Joel. There is no right answer to this question.
I would start breaking this down into a list of all possible failure points:
Database Server
Database
Middle Tier
Middle Tier Server
Application
Web Server
Then for each one of them, I would identify reasons for breakage, and how to recover from it without having downtime. The ones that I do not know the answers to, I would profess to as much.
For example, Let's build a list of reasons a Database server goes down. Since we are looking for 100% uptime, we ignore nothing - no matter how far fetched
Hardware goes bad
Power goes down
Network card goes bad
Operating System unexpectedly crashes
O.S. Upgrades break system
Dumb System Admin or DBA
Dumb Janitor
Some Possible solutions (considering SQL Server on Windows back-end)
Lock on door
Database Mirroring (with regular failover testing)
Multiple NICS
Clustering (with regular failover testing)
Get better people
You can basically keep answering this question until the interviewer throws in the towel because there really isn't the One-Right-Answer to this question.
That's a pretty broad question. If they expect zero downtime, tell them to forget about it or turn all of their profits over to building redundancy. Now, if they just want "five 9's, or 99.999% uptime" then we can talk. :)
You can usually answer these kinds of questions with the usual canned blather about building a sustainable, automatic, build environment that includes extensive unit testing. Using design patterns like MVC or similar can help with testability. Perform regular security audits. This is much bigger than just a development question, this is a question about network and server architecture, maintaining secondary and tertiary data centers, etc. These kinds of question really give you a chance to make the interviewer feel important.
I'm part of a software development company where we do custom developed applications for our clients.
Our software uses MS SQL Server and we have encountered some customers which do not have a DBA on staff to manage the databases or if they do, they lack the necessary knowledge to perform their job adequately.
We are in the process of drafting a contract with one of those customers to provide development services for new functionality on our software during the next year, where they have an amount of hours available for customization of our software.
Now they want us to include also a quote for database administration services and the problem is that they are including a clause that says that those services will be provided only when they request it.
My first reaction is that db administration is an ongoing process and not something that they can call us once a month to come for a day or two. I'm talking about a central 1TB+ MSSql Cluster and 100 branch offices with MSSql Workgroup edition.
My question is for any suggestions on how I could argue that there must be a fixed amount of hours every month for dba work and not only when their management thinks they need it (which I’m guessing would only be when they have a problem).
PS: Maybe this will be closed as not programming related. But I'm a programmer and I have this problem. My work is software development but i don't want to lose this client and the only solution I can think of is to find a way for the client to understand the scope so we can hire a qualified DBA to provide them with the service they require.
Edit: We are in a Latin American country with clients in the Spanish speaking region. My guess is that in more developed countries there is a culture that knows how delicate the situation is.
This is definitely one of those 'you can lead a horse to water, but you can't make them drink' situations.
My recommendation here would be to quote the DBA services as hourly, and make the rate high enough that you can outsource the work if you decide you want to. When (not if) the SQL servers start to have problems, the firm is on the hook.
I would also recommend that you include in your quote a non-optional 2 hour database technology review once per year. This is your opportunity to say 'You spent XXX on database maintenance this year, most of which was spent fighting fires that could have been easily avoided if you had just spent XXXX/4 and hired a DBA. We care about you as a customer, and we want you to save money, so we really recommend that you commit to using a DBA to perform periodic preventative maintenance'.
I would also recommend that you categorize any support requests as having root cause b/c of database maintenance vs other causes. This will let you put a nice pie chart in front of the customer during their annual review (which they are going to pay you to perform). It is critical to manage the perception so they don't think your code is causing the problems. You might even go so far as to share these metrics (db related issue vs non-db related issue) with them on a quarterly basis.
Sometimes people need to experience pain before they change. The key is to not be in between the hammer and their thumb as they learn the lesson, and hourly quoted work is one way of doing this.
As a side note, this sort of question is of great interest to a large number of developers. I'd say that this sort of thing could impact a programmer's quality of life more than any algorithm or library question ever could. Thanks for asking it!
No DBA on a system that size is a disaster waiting to happen. If they don't understand that, they are not qualified to run a database that size. I'd recommend that they talk to other companies with similar sized databases and have them ask them about their DBAs and what they do for them, and if they think they could survive without them.
Perhaps the link below from MS SQL Tips could give you some good talking points. But people who aren't technical wont respond to a technical explanation of the necessity of good DBA you are likley going to have to work toward proving the cost of bad DBA. Work out the worst case scenarios and see how they feel about them. If you can make it seem like a good financial move (and I think we all know it is) it will be an easy sell.
http://www.mssqltips.com/tip.asp?tip=1278
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A potential customer has asked me to look at some promotional flyers for a couple of apps which fall into the contact management / scheduler category. Both use Filemaker as their backend. It looks like these two apps are sold as web apps. At any rate I had not heard of Filemaker in about ten years, so it was surprising to see it pop up twice in the same sitting. I think it started out as a Mac platform db system.
I am more partial to SQL Server, MY SQL, etc, but before make any comments on Filemaker, I'd like to know some of the pros and cons of the system. It must be more than Access for Mac's, but I have never run across it as a player in the client / server or web app arena.
Many thanks
Mike Thomas
Calling Filemaker Pro, Access for the Mac is kind of like saying, Mac OS X is Windows for the Mac. They're both in the same category of software, they're integrated programming environments. It's like you have MySQL, PHP, HTML and your editor put together in a GUI. Comparing the two, they both have pros an cons. Here are the pros and cons of using Filemaker Pro vs PHP/MySQL/HTML in my experience.
Pros:
Easy to get started
Easy to deploy locally, turn on sharing and connect from another client
Cross-platform (Mac OS X, Windows, iOS)
There are many plugins available to extend functionality
Includes starter solutions
Anyone with access can edit the program
For the most part, drag and drop programming
Changing field/database/script names after the fact is free
Has some neat built in tricks like built in graphs, tab controls, web viewers
Built in support for importing exporting excel, cvs, tab-formatted
Cons:
Inflexible: it does what it does well, but if you need more your out of luck for the most part
Expensive compared to the free alternative: It costs about $100 per year for a local user, $150 per developer, if you are using it as a website you need specialized hosting, which tends to cost more. In addition the server part of the software is about $300-$800 a year
The plugins required to extend functionality can be expensive as well
Pretty much only drag and drop programming, you can only use predefined script steps, relationships are made by making a graph
Source control is problem
Lack of scalability
Unable to copy and paste/import or export some items from solutions
Requires the mouse to access functionality
Layout design is fairly static and dated (this is improving with the Filemaker 12 and above)
In general I would say that if you're developing exclusively for the web or a large organization Filemaker Pro probably isn't the best fit. It's difficult to have multiple people developing on the same solution. On the other hand, for a smaller organization in need of a customizable in-house database it could be a great boon. You can build rather complicated applications very quickly with it if your willing to deal with it's deficiencies.
Pros:
It's cheap
Cons:
It's cheap(ly made)
It's non-standard (easy to find
MySQL/Oracle/MSSQL/Access experts
but nobody knows Filemaker)
Using subpar and/or nonstandard technologies only creates technology debt. I've never found a respectable dev that actually enjoyed (or wanted to) using this niche product.
In my opinion this product exists because it is Access for Macs, and it gained enough of a userbase and existing applications that enough people bought each upgrade to keep it in business. There are many products on the market that still exist because it's users are locked in, not because it's a good choice.
I'll admit to bias on this subject -- I work with one of the larger FileMaker development shops out there, and have written the odd book on the subject. We actually employ many respectable developers who love using FMP. I'll try to keep it brief. :-)
FileMaker Pro is a rapid app development tool. It's primarily client-server, though it has some very respectable web publishing capabilities which work well for many applications. It is not SQL-based, but does have ODBC and JDBC interfaces, as well as an XML/HTTP interface.
As far as lock-in, FileMaker Inc has grown sales steadily, with very significant growth in new users who are attracted to the platform's solidity and ease of use.
I think Matt Haughton nailed it -- for the right applications, FMP is simply the best choice going. That said, your customer is looking at apps written in FMP Pro, and you need to evaluate those apps on their own merit. They may be good instances of FMP development, or they may not.
To know more about FMP's fitness for the task, we'd need to hear more about the proposed application and user base. Are these indeed web apps, or client-server? How many users will be using it? Do they work at one or two site, or are they spread across the Internet?
Happy to elaborate further if there's more interest.
FileMaker is designed to integrate very simply with other databases and client applications. If you are looking at building a complicated distributed system, look elsewhere.
FileMaker is NOT good to use as a front-end to another datasource due to the design goals of the External SQL Data Sources (ESS) feature set, and it is NOT good to use as a back-end to anything other that the FM client due to slow and buggy ODBC drivers. The nature of FileMaker's architecture means it doesn't scale very well with complicated solutions regardless of how well it can integrate with other systems.
Here's a developer's perspective on some limitations I've found when teaming FileMaker with other back-ends and ODBC clients:
The ODBC driver is limited, slow, and leaks memory on the client-side. The xdbc_listender.exe has similar memory leaking issues on the server side and will eventually crash when it uses a certain amount of RAM. We have a scheduled script to restart it each night.
FileMaker needs to load all related databases into memory before it can connect to a database. If its a complicated database, opening and closing a connection can be quite slow (1-2 seconds) depending on how it is structured, and more so if the database references tables in other FM databases because they need to be loaded as well. I get around this by creating persistent connections that stay open for the lifetime of the application. Although we try to minimize the number of open connections, we have yet to see a performance hit on the server.
The ODBC driver interprets queries in strange ways. For example I ran a query on 76k rows to UPDATE table_1 SET field_1 = 1 and it took 5 mins to perform the query because I think it split the one query into 46k update queries, one for each row. I know this because I watched it update the rows one-by-one in the FM client. So I don't trust the ODBC driver at all.
Here's another example of 3 different queries and how long they took searching on two date fields:
SELECT id FROM table
WHERE datefield1 = {d '2014-03-26'}
.5 seconds
SELECT id FROM table
WHERE datefield2 = {d '2014-03-26'}
.5 seconds
SELECT id FROM table
WHERE datefield1 = {d '2014-03-26'} OR datefield2 = {d '2014-03-26'}
1 minute 13 seconds!
We had problems with how FileMaker cached data from an SQL Express database. We tried to run the command to clear the cache, but it didn't always work (spent a lot of time investigating this).
FileMaker uses pessimistic locking of records; before editing (from the client or as part of an odbc transaction) FileMaker attempts to lock the row first.
The FileMaker Server service "prefers" being stopped using the Admin Console (though the Admin Console may sometimes be unable to stop it either). If the FileMaker Server service stops any other way (including power loss, via the management console, or even a normal system shutdown) then some of your databases may become corrupt. Same if a client crashes during an operation, or if the network connection is lost suddenly. The solution for a power loss is to write a batch script to try and automate the shutdown, and then buy a UPS and program it to execute your script before the juice runs out. And hope it works. Otherwise backup hourly using the built-in scheduler. Aside: SQL server doesn't have this problem because it can roll back uncommitted transactions.
Performing backups with the built-in scheduler actually suspends operations to the database during backup process. ie, if its a large database, then it might take a minute to backup and users will notice the pause because they wont be able to edit/insert, etc.
If you're using the FileMaker PHP API, take note that you can't use AND and OR together in the same request.
Running an intensive query using the ODBC driver might be fast on its own, but run the same query simultaneously (as in a multi-user environment) and it will slow down by about 300% exponentially. You will run into speed issues if you’re expecting a large volume of intensive queries to hit the database at the same time.
We have found that when the FileMaker ODBC driver says it has finished an update/insert operation, it still does not guarantee the transaction is committed; it appears that FileMaker will continue to hold the changes in the server cache until the auto-enter calculated fields are evaluated/indexed and then it saves to disc, meaning there may be more of a delay until the record is actually committed. So really the ODBC write operations are not always immediate writes, but rather eventual writes. This delay will be especially evident in complicated tables with many calculated fields and triggers.
Calculated fields may slow down execution and reading via the ODBC driver, depending on what is being evaluated. Try to read stored values whenever possible.
Using BLOB containers: Not Recommended. Storing documents such as PDFs in a container field will inflate your database file size, take longer to backup and complicate the retrieval and editing of those files via ODBC. It’s much easier to store files on a network share and write to the file on disk.
If you must use FM as a front-end solution to another database, make sure to carefully read FileMaker's Introduction to External SQL Sources.
Also refer to the the appropriate version FileMaker ODBC Guide found on their website.
Just a few comments on the subject
FileMaker is certainly cheaper than some enterprise solutions in licensing costs. However, the real cost benefit is in development time. The development life-cycle is typically orders of magnitude lower than other enterprise platforms (whatever the licensing costs of those platforms). By this I mean days instead of weeks, or weeks rather than months to develop some feature.
There is a strong argument that FileMaker is Access for the Mac. While this was a valid argument a few years ago, FileMaker has come into its own in recent years. It's worth noting that FileMaker is cross platform and used extensively on Windows as well as Mac. That being said there are still huge similarities and differences between FileMaker and Access, the truth is none of them have any bearing on your situation.
While FileMaker is non-standard it does support live connection to MySQL, MS SQL Server and Oracle.
Also, there are numerous FileMaker developers not as much as more standard platforms, but they are definitely about, if you let me know where you are I can put you in touch with a selection of developers in your area.
The important point I want to make is that in the correct context FileMaker is the best thing in the world at what it does - if you try to do something that it's not meant to do, you'll get stuck. However, it could support offices in 4 locations, it can and is being done.
Before you go and rewrite your system in some other platform you should get in touch with a FileMaker expert and see what they have to say about what you've currently got, writing more details on this site and having non-experts answer positively or negatively won't help you. In the end it has to be a business choice of costs vs. benefits.
No need to list anymore "Cons" - but here is a significant "Pro" - Filemaker Go. Once you have your database setup, download a ipad/iphone app (free for FM12) and run it from a mobile device. The database can be stored locally on the ipad/iphone or synced back to a host PC.
I'm sure this mobile solution is possible elsewhere - but the fundamental point is that an entry-level user (and I mean NO previous database experience) can create an impressive solution within a few weeks.
Personal experience: main database running FM 11 hosted on PC under my desk - 4 researchers scattered across the city collecting data on ipads - all syncing back to my PC. Previous solution was using paper and entering in data by hand.
FileMaker is an interesting app :) It started as an end-user tool and it still is one of very few database apps that a non-programmer can actually use. But somehow FileMaker developers managed to make it very scalable. There's no other platform where one can start with a useful tool and end up with a client-server app that for the whole company. In old days they used to have a splash screen that captured this very idea (I only found an imperfect version):
I.e. something as simple as a file cabinet that can grow quite big.
All FileMaker pros and cons come from its origin. As an end-user tool it's very much unlike other DBMS apps. No SQL. No real programming: scripts are basically macros that repeat user actions in a slightly more general way with variables and some logic. Lots of limitations; e.g. a list view cannot have a sidebar; a dynamic value list is always sorted alphabetically; to open a Save As dialog and read back the file name you'll need a plug-in; and so on. For a programmer this can be very frustrating, because most his assumptions will be wrong. And existing apps written by non-programmers are not exactly paragons of clarity and solid design.
But if you manage to overcome the obstacles you'll find a rather good RAD for client-server, single-user, web, and mobile apps, that stays rather usable over WAN, with such niceties as runtime and kiosk mode.
Having said that, I'm not quite sure about generic contact management and scheduling apps in FileMaker. If this is what they are, then they should be unlocked, so the customer can make changes; or they have to be niche apps that do for the customer what nothing else does.
Filemaker is enormously powerful and versatile. Excellent multi-user support. You can create wonderful solutions in Filemaker with document management, web interface, iphone interface, automated publishing support, scheduled scripts, PDF/Excel/HTML reports, XML support, caller ID record lookup, integration of web data (UPS & Fedex linked to order record for example). Extensible with plugins. It's like being in the Home Depot of data. Don't try to build Amazon; other than that what can't you build with it, and faster app dev than most anywhere else?
It has been more than a year now since I run through FM and use it in developing solutions for various clients. The following are my FM experience:
learning curve is much less than using the hard coded industry standard technology;
it can fit well as to industry standards platforms because of it's ODBC and JDBC connectivity. Your data is not locked in FM and other data format can get in FM;
it fits well as front end and back end solutions.
FM can match enterprise platform having a right database design and deployment i.e. workgroup or department oriented solutions. This is data to it's workgroup owner and make it available for other workgroups or departments;
FM is fits well for rapid application development that employs prototyping;
FM has many more capabilities you therein...
I suggest you try it yourself and I'm sure you'll love the stuff FM can offer!
Happy computing...
A little research has made me think that FileMaker is indeed Access for Mac, but perhaps a little more robust. I worked with Access for years, never really liked it, and am glad to be away from it (I always held a grudge for MSFT killing FoxPro, which I did like).
It is hard for me to imagine it as a good solution for a web based app used by offices in four locations around the country, plus many others logging on from home, etc.
Using it does not make much sense when MySQL, SQL Server, etc are available for the data storage and ASP.NET, PHP, Ruby etc are there for the programming.
Mike Thomas
While the comparisons to "Access for Mac" is inevitable, there are some important distinctions that have to be made.
FileMaker databases can be shared out to more than one person provided 1 of 2 things happen. One, a person on your network opens the DB and shares it from their computer, acting as the host. Two, you buy and install FileMaker server which hosts the DBs.
Also it's been my experience that while FileMaker developers LOVE FM, they're having to learn other technologies because more and more government agencies (my primary employer the past 10 years) are moving off of FM and into SQL Server, Oracle and to some extent Access and open source. FileMaker skills are becoming less and less in demand in the public sector, so getting support for these applications is harder and consequently, more expensive.
That being said, we have a FM server and FM 5.5 clients running an application that has been rock solid for the past 5 years.
i've been using FM for more than a year now. i'm doing and providing solutions for SMBs using the SQL standard for several years. i love those SQL stuff, but just a year a ago i run through FM Pro 9 and have it a try. amazingly, i got all i wanted in just a short time. in my experience as developer, FM Pro impressed me the way it does things.
true enough, FM is not an industry database standard but a good number of its features can compensate to what "standard" is being required of. FM pro has live connectivity to MySQL, MS SQL Server and Oracle. for me, it doesn't make sense to speak about standard if you can move your data around from FM to other platforms and vice-versa.
well, this note can't make that much convincing. it's good to try it for yourself... especially now that FM has its new version 10. believe me... you'll love it...
happy computing.
Two points seem to dominate this discussion and need consideration:
Non-Standard and what Government Agencies are doing.
Let's consider the small business owner or the single user both of whom a creating databases to meet their needs.
Now it doesn't matter what the government is doing, this is your database for your employees. Do what you want (as long as its legal, of course).
Non-Standard, well often this is the best idea since what you want to do works for you. Name your fields and tables as you like and later on rename this as you prefer. Don't try this with dbf or sql... Anyone remember those 'standard' file names bks1999.dbf bks2000.dbf Keep in mind that 'standards' exist because someone else wrote them before you arrived, not because they are the best possible idea.
And yes, there are a lot of 'bad' Filemaker solutions but they are working and supporting hundreds of thousands of people. But try to improve one of these bad solutions and compare that effort to improve a similarly bad dbf solution. A renamed field filters effortlessly through thousands of scripts and scripts in related Filemaker files. In a dbf solution it can become a nightmare as each instance has to be manually retyped.
One real test would be to compare how easily Filemaker can work with SQL, etc. as compared to other applications. That might be interesting. I've never done that but I bet I could create a working file in very little time that works with such data.
I have always said that every developer should use and be familiar with all of the tools.
25 years with Filemaker Pro, 3 years with FoxPro, 2 with 4D, etc.
Lots of comments about FileMaker being non-standard. But what is "standard"? By "standard", many people mean that a database supports Structured Query Language (SQL) (ISO Standard 9075) and FileMaker has and continues to support SQL. How every database engine supports SQL is proprietary to every database. Now it might be open source such as MySQL, but SQL is a standard to support, not the underlying language of how it is accomplished.
When most people talk about databases, they are only talking about the backend tables and schema. The front end user interface is frequently something else. And most of them now render those results as html pages via open standards like PHP. Again, FileMaker fully supports PHP calls and Apache or IIS (depending on which OS platform you are on).
So I would disagree with people saying FileMaker is non-standard.
What is unique about FileMaker is its tight integration between the schema and the User Interface. This is similar to Apple's tight integration between hardware and the Operating system, which has some nice benefits. Interestingly, FileMaker is owned by Apple, but I guess that is another topic.
Generally, FileMaker's User Interface is considerably easier to use than most open standards and most people stick to FileMaker's client User Interface instead of web interfaces. There are still a number of things supported only in FileMaker User Interface that can't be duplicated in a web browser.
FileMaker really makes rapid application development much easier with its close integration of schema and user interface. This makes development cost a whole lot less in most cases.
FileMaker's database services can be spread among up to 3 machines giving it primitive load balancing abilities with web services. While FileMaker easily supports hundreds of users, if you go into thousands of simultaneous users, many SQL only databases (eg Oracle, MS SQL Server, MySQL, Postgres) are designed to better spread out the load across more machines. Basically, if you have high simultaneous transactions, FileMaker is not your solution. For example, a company with many point of sale terminals from all over the county hitting it at the same time.
While FileMaker supports SQL and PHP, using it only that way is a waste of the money spent on the license for the FileMaker User Interface. It would not be a cost effective solution to develop a web front end and pay the full FileMaker license cost for only a backend. So, FileMaker's support of PHP and SQL is best combined with companies that have an in-house solution for staff, but also want to integrate that with their web development team for outside customers.
One last note is that FileMaker's tight integration of schema and User Interface makes security much easier. Obviously you have to set up the groups and users and I usually integrate FileMaker with Active Directory (or Open Directory). But when you use the FileMaker Client and Server connections, turning on encryption security is a single checkbox on the server. FileMaker handles all of the certificates and uses an AES 256bit cipher (at least since version 11, maybe before then too). Currently, the US Government considers that approved for up to and including the first level of Top Secret communications. In typical SQL systems, there is a lot of work to configure security on the database end as well as the user interface end of things and it is much more work than a single checkbox.
FileMaker's target audience has been small to medium sized companies, usually with 5 to 200 users, and it is a well priced product for rapid application development of databases for companies of that size.
And I can't end this comment without commenting on how easy it is to create and deploy a mobile solution on iOS devices like iPads and iPhones. FileMaker Go is a free app for use on these mobile devices and they fully support the same user interface and security. In fact, I am aware of one company that uses FileMaker as a front end interface for their Oracle database simply for access on iPhones. Expect a lot more in the mobile market in the future and FileMaker is clearly targeting mobile users.
Just to add my 2¢ to the already given answers: Everything everyone has written in the voted answers is true about Filemaker. The product is robust enough to warrant both positive and negative opinions.
I'm not a pro enough to speak to your concerns but there are a number of large complex applications written in FMP that you may want to look at. Jungle Software is a good place to start.
The down side to FMP for me as a user of some of those apps is that they come with a stack of files. The runtime of a FMP application isn't packaged as a bundle so it can look a bit complex with a large app. We did some tests a long time back because FMP had a reputation of being slow. At that time (12 years ago) FMP needed to index the db or it was slow but once it was indexed it was as fast as anything else we tested. It's big upside for semi pros is that it is very easy to do basic stuff and end up with working tool. My experience with Access was extremely negative so I wouldn't compare it at all with FMP.
In the end it doesn't really mater what it was written in, if the software does what you want and is stable buy it. If it doesn't don't. It is very easy to get data in and out of FMP so the proprietaryness of the db format doesn't really enter into it.