BorlandTalk.com Borland discussion newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Possibly OT: Transactions in XML/CSV          BorlandTalk.com Forum Index -> Delphi OO design View previous topic :: View next topic   Author Message Jeffrey A. Wormsley Guest Posted: Wed Feb 02, 2005 4:34 pm    Post subject: Possibly OT: Transactions in XML/CSV I've been researching OPF's, and many of the examples I see use XML and/or CSV because it is simple to use. The one I've looked at most recently is tiOPF, and just reading through it, it struck me that all of the talk about transactions doesn't apply to XML or CSV, the first two backends covered. Also in the whitepaper about tiOPF, the Factory pattern was discussed with reference to compression of data, and that got me to thinking. If your XML or CSV data were to be stored compressed in a ZIP or Zlib file, then opening a table would be in effect unzipping it. Starting a transaction would be updating the ZIP to the current table state. Committing a transaction would be the same. Rolling back a transaction would be throwing away the table files and unzipping the file again. Obviously, this is single user/single transaction, but it could be useful for small, local data, as well as for proofing out your transaction code for example apps. I suppose in memory tables could do the same with saving to file. Just something that came to me last night. Possibly of use to no one. Jeff. Back to top Peter Morris [Droopy eyes Guest Posted: Wed Feb 02, 2005 5:03 pm    Post subject: Re: Possibly OT: Transactions in XML/CSV Quote: Just something that came to me last night. Possibly of use to no one. Including yourself ;-) Zipping would be very slow. In fact, for a lot of data even XML / CSV would be very slow and unusable. For single-user I'd choose FB-Embedded. -- Pete ==== ECO Modeler, Audio compression components, DIB graphics controls, FastStrings http://www.droopyeyes.com Read or write articles on just about anything http://www.HowToDoThings.com My blog http://blogs.slcdug.org/petermorris/ Back to top Jim Cooper Guest Posted: Wed Feb 02, 2005 11:19 pm    Post subject: Re: Possibly OT: Transactions in XML/CSV Quote: In fact, for a lot of data even XML / CSV would be very slow and unusable. Hmmm, dunno. Depends on your parsing code I suppose. In general for single user use it is much much faster to load data from a file than a database. This really only starts to become a problem with very large amounts of data. Have you seen Prevayler? Works quicker than a database, mostly. Cheers, Jim Cooper __________________________________________ Jim Cooper [email]jcooper (AT) tabdee (DOT) ltd.uk[/email] Tabdee Ltd http://www.tabdee.ltd.uk TurboSync - Connecting Delphi to your Palm __________________________________________ Back to top Peter Morris [Droopy eyes Guest Posted: Thu Feb 03, 2005 9:31 am    Post subject: Re: Possibly OT: Transactions in XML/CSV Quote: Hmmm, dunno. Depends on your parsing code I suppose. In general for single user use it is much much faster to load data from a file than a database. This really only starts to become a problem with very large amounts of data. That's my point really. 100 objects would be pretty instant, whereas 100 million would take 10 minutes. The benefit of a "real" db is that it works with sub-sections of the data rather than the whole database. Quote: Have you seen Prevayler? Works quicker than a database, mostly. Yes, but that works mainly in memory and has a periodic backup to disk in a separate thread. That's not the same approach as reading/writing all data from/to disk each time you work with a transaction :-) -- Pete ==== ECO Modeler, Audio compression components, DIB graphics controls, FastStrings http://www.droopyeyes.com Read or write articles on just about anything http://www.HowToDoThings.com My blog http://blogs.slcdug.org/petermorris/ Back to top Jim Cooper Guest Posted: Thu Feb 03, 2005 10:04 am    Post subject: Re: Possibly OT: Transactions in XML/CSV Quote: That's my point really. 100 objects would be pretty instant, whereas 100 million would take 10 minutes. There is a cut-off point, of course. But how many single-user apps use 100 million records? None that I know of :-) It is a viable option most of the time. However, if you ever want it to scale... Quote: Yes, but that works mainly in memory and has a periodic backup to disk in a separate thread. That's not the same approach as reading/writing all data from/to disk each time you work with a transaction You only ever have to write to disk for a transaction And Prevayler does read everything in at the beginning. It's a cool system, and there are stats somewhere on their site that show where the cross-over to a database becomes quicker. Cheers, Jim Cooper __________________________________________ Jim Cooper [email]jcooper (AT) tabdee (DOT) ltd.uk[/email] Tabdee Ltd http://www.tabdee.ltd.uk TurboSync - Connecting Delphi to your Palm __________________________________________ Back to top Jeffrey A. Wormsley Guest Posted: Thu Feb 03, 2005 4:41 pm    Post subject: Re: Possibly OT: Transactions in XML/CSV "Peter Morris [Droopy eyes software]" <pete (AT) remove (DOT) this.droopyeyes.com> wrote in news:420107fc$1 (AT) newsgroups (DOT) borland.com: Quote: Zipping would be very slow. In fact, for a lot of data even XML / CSV would be very slow and unusable. For single-user I'd choose FB-Embedded. Certainly. But for small sets, such as used in examples or demos, it would be fine. More of a learning tool for transactions, than a production environment. Some small apps where the expected data volume is small (a few tens of K, perhaps) might could get by with it. Certainly nothing to use in a large or even medium scale app. Jeff. 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