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  • How do I prove I should put a table of values in source code instead of a database table?

    - by FastAl
    <tldr>looking for a reference to a book or other undeniably authoritative source that gives reasons when you should choose a database vs. when you should choose other storage methods. I have provided an un-authoritative list of reasons about 2/3 of the way down this post.</tldr> I have a situation at my company where a database is being used where it would be better to use another solution (in this case, an auto-generated piece of source code that contains a static lookup table, searched by binary sort). Normally, a database would be an OK solution even though the problem does not require a database, e.g, none of the elements of ACID are needed, as it is read-only data, updated about every 3-5 years (also requiring other sourcecode changes), and fits in memory, and can be keyed into via binary search (a tad faster than db, but speed is not an issue). The problem is that this code runs on our enterprise server, but is shared with several PC platforms (some disconnected, some use a central DB, etc.), and parts of it are managed by multiple programming units, parts by the DBAs, parts even by mathematicians in another department, etc. These hit their own platform’s version of their databases (containing their own copy of the static data). What happens is that every implementation, every little change, something different goes wrong. There are many other issues as well. I can’t even use a flatfile, because one mode of running on our enterprise server does not have permission to read files (only databases, and of course, its own literal storage, e.g., in-source table). Of course, other parts of the system use databases in proper, less obscure manners; there is no problem with those parts. So why don’t we just change it? I don’t have administrative ability to force a change. But I’m affected because sometimes I have to help fix the problems, but mostly because it causes outages and tons of extra IT time by other programmers and d*mmit that makes me mad! The reason neither management, nor the designers of the system, can see the problem is that they propose a solution that won’t work: increase communication; implement more safeguards and standards; etc. But every time, in a different part of the already-pared-down but still multi-step processes, a few different diligent, hard-working, top performing IT personnel make a unique subtle error that causes it to fail, sometimes after the last round of testing! And in general these are not single-person failures, but understandable miscommunications. And communication at our company is actually better than most. People just don't think that's the case because they haven't dug into the matter. However, I have it on very good word from somebody with extensive formal study of sociology and psychology that the relatively small amount of less-than-proper database usage in this gigantic cross-platform multi-source, multi-language project is bureaucratically un-maintainable. Impossible. No chance. At least with Human Beings in the loop, and it can’t be automated. In addition, the management and developers who could change this, though intelligent and capable, don’t understand the rigidity of this ‘how humans are’ issue, and are not convincible on the matter. The reason putting the static data in sourcecode will solve the problem is, although the solution is less sexy than a database, it would function with no technical drawbacks; and since the sharing of sourcecode already works very well, you basically erase any database-related effort from this section of the project, along with all the drawbacks of it that are causing problems. OK, that’s the background, for the curious. I won’t be able to convince management that this is an unfixable sociological problem, and that the real solution is coding around these limits of human nature, just as you would code around a bug in a 3rd party component that you can’t change. So what I have to do is exploit the unsuitableness of the database solution, and not do it using logic, but rather authority. I am aware of many reasons, and posts on this site giving reasons for one over the other; I’m not looking for lists of reasons like these (although you can add a comment if I've miss a doozy): WHY USE A DATABASE? instead of flatfile/other DB vs. file: if you need... Random Read / Transparent search optimization Advanced / varied / customizable Searching and sorting capabilities Transaction/rollback Locks, semaphores Concurrency control / Shared users Security 1-many/m-m is easier Easy modification Scalability Load Balancing Random updates / inserts / deletes Advanced query Administrative control of design, etc. SQL / learning curve Debugging / Logging Centralized / Live Backup capabilities Cached queries / dvlp & cache execution plans Interleaved update/read Referential integrity, avoid redundant/missing/corrupt/out-of-sync data Reporting (from on olap or oltp db) / turnkey generation tools [Disadvantages:] Important to get right the first time - professional design - but only b/c it's meant to last s/w & h/w cost Usu. over a network, speed issue (best vs. best design vs. local=even then a separate process req's marshalling/netwk layers/inter-p comm) indicies and query processing can stand in the way of simple processing (vs. flatfile) WHY USE FLATFILE: If you only need... Sequential Row processing only Limited usage append only (no reading, no master key/update) Only Update the record you're reading (fixed length recs only) Too big to fit into memory If Local disk / read-ahead network connection Portability / small system Email / cut & Paste / store as document by novice - simple format Low design learning curve but high cost later WHY USE IN-MEMORY/TABLE (tables, arrays, etc.): if you need... Processing a single db/ff record that was imported Known size of data Static data if hardcoding the table Narrow, unchanging use (e.g., one program or proc) -includes a class that will be shared, but encapsulates its data manipulation Extreme speed needed / high transaction frequency Random access - but search is dependent on implementation Following are some other posts about the topic: http://stackoverflow.com/questions/1499239/database-vs-flat-text-file-what-are-some-technical-reasons-for-choosing-one-over http://stackoverflow.com/questions/332825/are-flat-file-databases-any-good http://stackoverflow.com/questions/2356851/database-vs-flat-files http://stackoverflow.com/questions/514455/databases-vs-plain-text/514530 What I’d like to know is if anybody could recommend a hard, authoritative source containing these reasons. I’m looking for a paper book I can buy, or a reputable website with whitepapers about the issue (e.g., Microsoft, IBM), not counting the user-generated content on those sites. This will have a greater change to elicit a change that I’m looking for: less wasted programmer time, and more reliable programs. Thanks very much for your help. You win a prize for reading such a large post!

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  • Search and replace global modifier

    - by mrucci
    Is there any reason why non-global/first-occurrence substitution is the default in many text editing programs (vim, sed, perl, etc.)? I am talking about the /g flag of search and replace commands like: :s/pan/focaccia/g # in vim sed 's/sfortuna/fortuna/g' # with sed that will substitute every occurrence of the search pattern with the replacement string. After (not too) many years of vim and sed usage I still did not find any use case for non-global substitutions. Is there some valid historical reason? Or it is because it is? Thanks.

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  • Monitoring over Time with Nagios: How?

    - by David
    Nagios in its standard usage monitors with point-in-time checks: either something is - or is not - true. Other tools like SGI's PCP, HP's MeasureWare, and SEC provide monitoring over time - monitoring things like average disk access time over the last five minutes, or other similar items. Is there anything like this for Nagios? I'm already running NDOUtils, which seems like a natural source for such data. I'd like to have something that would monitor and fire off alarms based on a time-based check using historical data. Is there anything like this for Nagios?

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  • Should we denormalize database to improve performance?

    - by Groo
    We have a requirement to store 500 measurements per second, coming from several devices. Each measurement consists of a timestamp, a quantity type, and several vector values. Right now there is 8 vector values per measurement, and we may consider this number to be constant for needs of our prototype project. We are using HNibernate. Tests are done in SQLite (disk file db, not in-memory), but production will probably be MsSQL. Our Measurement entity class is the one that holds a single measurement, and looks like this: public class Measurement { public virtual Guid Id { get; private set; } public virtual Device Device { get; private set; } public virtual Timestamp Timestamp { get; private set; } public virtual IList<VectorValue> Vectors { get; private set; } } Vector values are stored in a separate table, so that each of them references its parent measurement through a foreign key. We have done a couple of things to ensure that generated SQL is (reasonably) efficient: we are using Guid.Comb for generating IDs, we are flushing around 500 items in a single transaction, ADO.Net batch size is set to 100 (I think SQLIte does not support batch updates? But it might be useful later). The problem Right now we can insert 150-200 measurements per second (which is not fast enough, although this is SQLite we are talking about). Looking at the generated SQL, we can see that in a single transaction we insert (as expected): 1 timestamp 1 measurement 8 vector values which means that we are actually doing 10x more single table inserts: 1500-2000 per second. If we placed everything (all 8 vector values and the timestamp) into the measurement table (adding 9 dedicated columns), it seems that we could increase our insert speed up to 10 times. Switching to SQL server will improve performance, but we would like to know if there might be a way to avoid unnecessary performance costs related to the way database is organized right now. [Edit] With in-memory SQLite I get around 350 items/sec (3500 single table inserts), which I believe is about as good as it gets with NHibernate (taking this post for reference: http://ayende.com/Blog/archive/2009/08/22/nhibernate-perf-tricks.aspx). But I might as well switch to SQL server and stop assuming things, right? I will update my post as soon as I test it.

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  • Subclassing NSObject, can it cause problems?

    - by Sheehan Alam
    I have a very basic data class that is subclassed from NSObject. I declare a few strings, make sure they have properties (nonatomic, copy), and synthesize them. The only method I implemented was dealloc() which releases my strings. Can any memory problems arise from just this? Are there any other methods I need to implement?

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  • SQL Server cluster performance baseline

    - by Dwight T
    Currently I'm tasked with getting a good performance baseline on a SQL 2005 cluster. The main db on the server is for Sharepoint, but I would like to add other dbs on the cluster. I do have access to Quest's Performance Analysis tool to help. What are key factors to look at to see if the cluster can handle additional dbs? Do you look at different performance indicators for a cluster vs a stand alone sql server? One db will be a low usage transactional db and a read only db that is used for sales data. Thanks Dwight

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  • how to create partition on windows CE device

    - by mack369
    Is there any tool to create a new partition on windows CE device? Device has a NAND flash memory and initially there were two partitions. Using Storage manager in Control Panel I was able to delete one partition but when I want to create it again, I get an error message: "Unable to create partition".

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  • Built in Analyzer in Xcode 3.1.4

    - by Mustafa
    Hi all, I wonder if the built in Analyzer in Xcode 3.1.4 makes it redundant to use LLVM/Clang Static Analyzer separately? Please refer to the original article here: Finding memory leaks with the LLVM/Clang Static Analyzer Thanks.

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  • Performance tuning of a Hibernate+Spring+MySQL project operation that stores images uploaded by user

    - by Umar
    Hi I am working on a web project that is Spring+Hibernate+MySQL based. I am stuck at a point where I have to store images uploaded by a user into the database. Although I have written some code that works well for now, but I believe that things will mess up when the project would go live. Here's my domain class that carries the image bytes: @Entity public class Picture implements java.io.Serializable{ long id; byte[] data; ... // getters and setters } And here's my controller that saves the file on submit: public class PictureUploadFormController extends AbstractBaseFormController{ ... protected ModelAndView onSubmit(HttpServletRequest request, HttpServletResponse response, Object command, BindException errors) throws Exception{ MutlipartFile file; // getting MultipartFile from the command object ... // beginning hibernate transaction ... Picture p=new Picture(); p.setData(file.getBytes()); pictureDAO.makePersistent(p); // this method simply calls getSession().saveOrUpdate(p) // committing hiernate transaction ... } ... } Obviously a bad piece of code. Is there anyway I could use InputStream or Blob to save the data, instead of first loading all the bytes from the user into the memory and then pushing them into the database? I did some research on hibernate's support for Blob, and found this in Hibernate In Action book: java.sql.Blob and java.sql.Clob are the most efficient way to handle large objects in Java. Unfortunately, an instance of Blob or Clob is only useable until the JDBC transaction completes. So if your persistent class defines a property of java.sql.Clob or java.sql.Blob (not a good idea anyway), you’ll be restricted in how instances of the class may be used. In particular, you won’t be able to use instances of that class as detached objects. Furthermore, many JDBC drivers don’t feature working support for java.sql.Blob and java.sql.Clob. Therefore, it makes more sense to map large objects using the binary or text mapping type, assuming retrieval of the entire large object into memory isn’t a performance killer. Note you can find up-to-date design patterns and tips for large object usage on the Hibernate website, with tricks for particular platforms. Now apparently the Blob cannot be used, as it is not a good idea anyway, what else could be used to improve the performance? I couldn't find any up-to-date design pattern or any useful information on Hibernate website. So any help/recommendations from stackoverflowers will be much appreciated. Thanks

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  • T-SQL query with date range

    - by Moo
    Hi, I have a fairly weird 'bug' with a simple query, and I vaguely remember reading the reason for it somewhere a long time ago but would love someone to refresh my memory. The table is a basic ID, Datetime table. The query is: select ID, Datetime from Table where Datetime <= '2010-03-31 23:59:59' The problem is that the query results include results where the Datetime is '2010-04-01 00:00:00'. The next day. Which it shouldn't. Anyone? Cheers Moo

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  • Saving child collections with NHibernate

    - by Ben
    Hi, I am in the process or learning NHibernate so bare with me. I have an Order class and a Transaction class. Order has a one to many association with transaction. The transaction table in my database has a not null constraint on the OrderId foreign key. Order class: public class Order { public virtual Guid Id { get; set; } public virtual DateTime CreatedOn { get; set; } public virtual decimal Total { get; set; } public virtual ICollection<Transaction> Transactions { get; set; } public Order() { Transactions = new HashSet<Transaction>(); } } Order Mapping: <class name="Order" table="Orders"> <cache usage="read-write"/> <id name="Id"> <generator class="guid"/> </id> <property name="CreatedOn" type="datetime"/> <property name="Total" type="decimal"/> <set name="Transactions" table="Transactions" lazy="false" inverse="true"> <key column="OrderId"/> <one-to-many class="Transaction"/> </set> Transaction Class: public class Transaction { public virtual Guid Id { get; set; } public virtual DateTime ExecutedOn { get; set; } public virtual bool Success { get; set; } public virtual Order Order { get; set; } } Transaction Mapping: <class name="Transaction" table="Transactions"> <cache usage="read-write"/> <id name="Id" column="Id" type="Guid"> <generator class="guid"/> </id> <property name="ExecutedOn" type="datetime"/> <property name="Success" type="bool"/> <many-to-one name="Order" class="Order" column="OrderId" not-null="true"/> Really I don't want a bidirectional association. There is no need for my transaction objects to reference their order object directly (I just need to access the transactions of an order). However, I had to add this so that Order.Transactions is persisted to the database: Repository: public void Update(Order entity) { using (ISession session = NHibernateHelper.OpenSession()) { using (ITransaction transaction = session.BeginTransaction()) { session.Update(entity); foreach (var tx in entity.Transactions) { tx.Order = entity; session.SaveOrUpdate(tx); } transaction.Commit(); } } } My problem is that this will then issue an update for every transaction on the order collection (regardless of whether it has changed or not). What I was trying to get around was having to explicitly save the transaction before saving the order and instead just add the transactions to the order and then save the order: public void Can_add_transaction_to_existing_order() { var orderRepo = new OrderRepository(); var order = orderRepo.GetById(new Guid("aa3b5d04-c5c8-4ad9-9b3e-9ce73e488a9f")); Transaction tx = new Transaction(); tx.ExecutedOn = DateTime.Now; tx.Success = true; order.Transactions.Add(tx); orderRepo.Update(order); } Although I have found quite a few articles covering the set up of a one-to-many association, most of these discuss retrieving of data and not persisting back. Many thanks, Ben

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  • How can user change the jre parameter values after the exe is generated in Launch4j?

    - by Wing C. Chen
    Is it possible to change the jre parameter values after the exe file is generated through Launch4j? The ideal scenario is like this: The default parameter values are applied when the program is started. However, when the user wants to change some jre parameter values, he goes to a .ini file, MyProgram.ini for example, changes the values there, and the new values will be applied next time the program is started. I think eclipse uses the same way for its memory and some other parameter settings.

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  • reducing Windows 7 size

    - by Sejanus
    My Windows 7 uses around 16 GB while Windows XP only around 4 GB hard disk space. Seems weird. I use Windows only for gaming so I dont need a lot of stuff they have to offer. What is the best way to reduce Windows 7 size? What can I delete / uninstall and how? Also I'd like reduce RAM and processor usage as much as possible (as long as it doesnt hurt game performance)... turn off all that fancy stuff and so on. What can I turn off and how? Thanks in advance!

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  • On RouterOS, how will transparent proxying (with DNAT) affect reporting of netflows?

    - by Tim
    I have a box running Mikrotik RouterOS, which is set up to do transparent web proxying, as described here. In short, this means that I have a firewall rule for destination NAT causing any port 80 traffic to get redirected to port 8080 on the router, which is received by the Mikrotik local web proxy. The local web proxy then makes the web request on the client's behalf, in this case to a parent web proxy server (which in turn does the real web request). My question is, how will this two-part process get reported in the logging of traffic flow information (netflows)? Looking at the logged information, what I seem to be seeing is this: One flow recorded from client machine (private IP) to remote proxy (8080) Another flow recorded from router to remote proxy (8080) The original request that the client made to port 80 isn't recorded. I want to write code to analyse traffic usage, so I want to be sure I'm not losing information if I discard the latter of these.

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  • OLTP Sql Server RAID configuration with 10 disks, allocation Unit and disk stripe size

    - by Chris Wood
    On a new db server I only have 10 disks to play with, The usage is about a booking every 3-5 seconds, so not high volume, I know compromises have to be made, but my initial thoughts are - DISK 1 & 2 - RAID 1 - OS DISKS 3,4,5,6 - RAID 10 - Data, Indexes & TempDB DISKS 7,8,9,10 - RAID 10 - Logs & Backup Full backups will take place when there is virtually no traffic on the website so not bothered about the contention with the logs. disk 3-10 - 8kb NTFS unit allocation size disk 3-10 - 64kb Disk Stripe size does this seems to be sensible, any other considerations I have omitted ? thanks

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  • Caching Reverse-Proxy ISP Host for a Low-Bandwidth Server

    - by Casey
    I am building a webcam w/ HTTP server that will be running from a low-bandwith connection. The content on the site will be changing every 5 to 10 minutes. Instead of serving files directly from this connection, are there hosting companies that can act as a reverse proxy for my site? Therefore, if nobody is using the site, the local internet connection remains idle. And if I receive 1000 hits all at the same time, only one HTTP GET is required, and the hosting company (on a fat pipe) continues serving the other 999 requests? This doesn't sound like a very common usage model, but I feel like this would be the optimal solution to my situation.

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  • Filtering Attributes with Weka

    - by hrzafer
    Hi eveyone! I have a simple question about filtering attributes in WEKA. Let's say I have 500 attributes 30 classes and 100 samples for each class which equals 3000 rows and 500 columns. This causes time and memory problems a you can guess. How do I filter attributes that occur only once or twice (or n times) in 3000 rows. And is it a good idea? Thank you

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  • organizing images by resolution with batch files

    - by Anthony
    Doing some digging I'm trying to figure out a command line solution for organizing very large archives of images based on their resolution into folders, 1920x1080, 1600x1200, 1600x900, etc. I've come across a few post on Superuser mentioning something called ImageMagick, is that the best method to the madness I'm trying to accomplish? I've never used any command line functions/applets/tools other then those that come from Microsoft. I'm rather new to command line usage but ive been enjoying the hell out of it using Powershell, xcopy and robocopy. I am slowly trying to push myself further into the Linux world with Ubuntu running on one of my physical machines as well as a virtual machine so that's an option as well.

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  • Change install path to /usr/bin instead of /usr/local/bin

    - by user1678788
    A simple question, but I have no concrete documentation to confirm my answer. When installing software with the make install command under a unix machine, the default path is going over to /usr/local/bin. I would like to update a package system-wide under /usr/bin. How (and where) do I change the command under make or make install to /usr/bin? Also - Can the package remain on /usr/local/bin but the systemwide usage of Python (the update being installed) be changed to /usr/local/bin from /usr/bin to avoid modifying the original installed version ?

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  • Why do my download speeds drastically vary during a download?

    - by J. Anthony Carter
    I watch the download speed rise and fall like waves in a storm. At night, during low bandwidth usage I have achieve speeds as high as 3.23 M/sec but the watch them decline to 250 K/sec. and then climb back up. Over and over. During the day my best is around 1.67 M/sec with lows into the 65 K/sec. On top of this, why does a download need to slow down when approaching the end of the download? It's not like a multi-hundred ton train needing to decrease speed as it approaches the station.

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  • Is it a good idea to have the operating system on a solid state drive?

    - by Kenji Kina
    There is something I don't quite understand. I know a SSD helps with OS load times, but I'm not sure if all this boost is only noticeable/interesting when booting, or gives an all around considerably better experience thereafter. I am interested in having a quick and responsive environment after booting, which leads me to think that it'd be better to spend the SSD capacity in my most used apps (and the page file? Another inside question) and not the OS itself. This, of course, means that I don't know just how much the OS reads/writes its files during normal usage. So, how good an idea is it to dump the whole 20GB+ of Windows 7 OS into the SSD (considering the hefty price per GB of SSD capacity) if I can put up with the usual hard disk boot times? Would I be missing on a lot if I didn't?

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  • Summary of the last decade of garbage collection?

    - by Ben Karel
    I've been reading through the Jones & Lin book on garbage collection, which was published in 1996. Obviously, the computing world has changed dramatically since then: multicore, out-of-order chips with large caches, and even larger main memory in desktops. The world has also more-or-less settled on the x86 and ARM microarchitectures for most consumer-facing systems. How has the field of garbage collection changed since the seminal book was published?

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