Programming a database, any info?
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Anthony Paul Cavalcanti Orti #1 / 25
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Programming a database, any info?
Hello all!! I'm a delphi 4 programmer and am in the process of creating a BDE replacement engine. I would like to know of any sites where I can get ANY info of the following : 1) Database design/programming tips. 2) The latest in database performance/storage theories, optimizations, etc.. 2) Algorithms used for storing records. 3) Algorithms used for indexes. 4) How to create a BDE replacement such that I can use my engine in place of the BDE and possibly retain use of the data aware components that Delphi supplies? In other words, I want people to be able to use the data aware components with it such as TDBGrid, TDBMemo, TDBEdit, etc... The info I need would pertain to creating a small to medium databases, not the Interbase, Oracle or Sybase type of monstrous databases. ANY help would be MUCH appreciated, even if it's some source code, an article, a link to a web page, a good DB book, etc... Thanks a lot!! :-) Anthony Ortiz
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Wed, 18 Jun 1902 08:00:00 GMT |
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Bj?rge S?the #2 / 25
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Programming a database, any info?
<<Anthony Paul Cavalcanti Ortiz: I'm a Delphi 4 programmer and am in the process of creating a BDE replacement engine. I would like to know of any sites where I can get ANY info of the following : 1) Database design/programming tips.
Well, concider this posting a database design tip in the Delphi/VCL context. << 2) The latest in database performance/storage theories, optimizations, etc.. 2) Algorithms used for storing records. 3) Algorithms used for indexes.
I really believe that the best reason for creating a BDE replacement including a database engine would be to achieve a behaviour different from the BDE. If you want a square, traditional cursor-based relational database, it's just not worth the time creating another one. Personally, I would never use a shareware db-engine unless I needed something different from the regular ones. I've been checking out a few of them, and I haven't found a good one yet. OK, the BDE isn't brilliant, but it is not a disaster compared to the rest of the world of traditional databases. The choice of a DB engine is an Important one, because all concepts are full of compromises, trading speed for security, fast read/write for disk space & memory, or the other way around. I suggest that you study one small file-based database and one SQL-server to make a decision about what level of functionality you want, and study the DBTABLES.PAS unit and the BDE32.HLP to see how things are done on the application side. << 4) How to create a BDE replacement such that I can use my engine in place of the BDE and possibly retain use of the data aware components that Delphi supplies? In other words, I want people to be able to use the data aware components with it such as TDBGrid, TDBMemo, TDBEdit, etc...
This locks you to creating a cursor-based database, because the interface for the DB-controls are designed for such. In short - create an equivalent to most parts of the BDE API, and create a modified DBTABLES unit (renamed, of course). <<The info I need would pertain to creating a small to medium databases, not the Interbase, Oracle or Sybase type of monstrous databases.>> On my 233MHz Laptop I run Oracle server on NT Workstation 4.0 starting the NT Server and Oracle. Startup takes about 2 minutes. On my 3.2 Gb HDD I have 2 small company databases, MS Office, an additional Win95, 4 Delphi versions and a lot of projects. I don't quite understand what is monstrous about that size ? MS Word uses more RAM than Oracle, and Delphi takes longer to load. The only monstrous about those is the price... I believe you would have quite a job outperforming Paradox or Oracle. IMHO, the most important feature missing in network-enabled databases from Paradox to oracle is that they don't provide a messaging service to notify other users when data changes in the database. If you implement this functionality, even I would concider taking a look at such a concept.. <<ANY help would be MUCH appreciated, even if it's some source code, an article, a link to a web page, a good DB book, etc...>> The book "Using Delphi 3" by Miller, Powell, et al. described how to create a custom dataset with Delphi. I'm afraid this was almost 100% discouraging. OK, it might be fun creating a datbase engine. It's a hell of a lot of work, and you'll learn a lot. But I don't see how these efforts could ever pay off unless you really need something different from the traditional Relational DB's. Good luck, anyway ! -- Bjoerge
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Wed, 18 Jun 1902 08:00:00 GMT |
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Alexander Muelle #3 / 25
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Programming a database, any info?
What I dont understand is that why database systems must be so complexe and difficult. What shall a database do? It should store data! But if you use the BDE you need thousends of dlls. Why? Could this not be easier done? Look at Delphi. To access a database you need a TTable, a TDataSet and special database controls. And all this just to use "a few" datasets. But then the people are wondering when the exe file is as large as a 10 gb hd ;) and when the app doesnt work just because a dll is missing ;). I certainly know that Oracle, Paradox & co. have been established as standard. But I think a new small&simple database solution would help developers worldwide enormously. Alex Quote:
> <<Anthony Paul Cavalcanti Ortiz: > I'm a Delphi 4 programmer and am in the process of creating a BDE > replacement engine. I would like to know of any sites where I can get > ANY info of the following : > 1) Database design/programming tips. > Well, concider this posting a database design tip in the Delphi/VCL context. > << > 2) The latest in database performance/storage theories, optimizations, etc.. > 2) Algorithms used for storing records. > 3) Algorithms used for indexes. > I really believe that the best reason for creating a BDE replacement including a database engine > would be to achieve a behaviour different from the BDE. If you want a square, traditional > cursor-based relational database, it's just not worth the time creating another one. Personally, I > would never use a shareware db-engine unless I needed something different from the regular ones. > I've been checking out a few of them, and I haven't found a good one yet. OK, the BDE isn't > brilliant, but it is not a disaster compared to the rest of the world of traditional databases. > The choice of a DB engine is an Important one, because all concepts are full of compromises, trading > speed for security, fast read/write for disk space & memory, or the other way around. I suggest that > you study one small file-based database and one SQL-server to make a decision about what level of > functionality you want, and study the DBTABLES.PAS unit and the BDE32.HLP to see how things are done > on the application side. > << > 4) How to create a BDE replacement such that I can use my engine in > place of the BDE and possibly retain use of the data aware components > that Delphi supplies? In other words, I want people to be able to use > the data aware components with it such as TDBGrid, TDBMemo, TDBEdit, > etc... > This locks you to creating a cursor-based database, because the interface for the DB-controls are > designed for such. In short - create an equivalent to most parts of the BDE API, and create a > modified DBTABLES unit (renamed, of course). > <<The info I need would pertain to creating a small to medium databases, > not the Interbase, Oracle or Sybase type of monstrous databases.>> > On my 233MHz Laptop I run Oracle server on NT Workstation 4.0 starting the NT Server and Oracle. > Startup takes about 2 minutes. On my 3.2 Gb HDD I have 2 small company databases, MS Office, an > additional Win95, 4 Delphi versions and a lot of projects. I don't quite understand what is > monstrous about that size ? MS Word uses more RAM than Oracle, and Delphi takes longer to load. The > only monstrous about those is the price... > I believe you would have quite a job outperforming Paradox or Oracle. > IMHO, the most important feature missing in network-enabled databases from Paradox to oracle is that > they don't provide a messaging service to notify other users when data changes in the database. If > you implement this functionality, even I would concider taking a look at such a concept.. > <<ANY help would be MUCH appreciated, even if it's some source code, an > article, a link to a web page, a good DB book, etc...>> > The book "Using Delphi 3" by Miller, Powell, et al. described how to create a custom dataset with > Delphi. > I'm afraid this was almost 100% discouraging. OK, it might be fun creating a datbase engine. It's a > hell of a lot of work, and you'll learn a lot. But I don't see how these efforts could ever pay off > unless you really need something different from the traditional Relational DB's. > Good luck, anyway ! > -- > Bjoerge
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Wed, 18 Jun 1902 08:00:00 GMT |
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Bruce Robert #4 / 25
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Programming a database, any info?
There are a number of good small databases around and if you don't need the functionality of the BDE then use one of them. However, there are some very good reasons why the BDE is the size it is and it does a reasonably good job at what it was designed to do. The BDE isn't really a database, rather it is an interface to a number of different databases. In that respect it is more like ODBC than dBase. For that reason, and that reason alone, it is more complex than dBase or Paradox by themselves. This is not to say that a comercial quality database is a simple thing to implement. If it needs to handle tables up into the 1,000K record count, multiple concurrent users, multi-segment ascending and descending indexes, and rich data types a database is by the nature of the problem going to have to have a fairly high degree of sophistication and, alas, complexity. What irks me the most are complaints about the size of the BDE. People seem to think nothing of installing a 250 MB office suite, or 300 MB game. Asking for 15 MB for data management is considered a crime? Come to think of it, I haven't read any rants about the size of Delphi itself. Surely those that think the BDE is too big and bloated must think that a Pascal compiler that weighs in at 80+ MB is a little over the top ;).
Quote: > What I dont understand is that why database systems must be so complexe > and difficult. What shall a database do? It should store data! But if > you use the BDE you need thousends of dlls. Why? Could this not be > easier done? Look at Delphi. To access a database you need a TTable, a > TDataSet and special database controls. And all this just to use "a few" > datasets. But then the people are wondering when the exe file is as > large as a 10 gb hd ;) and when the app doesnt work just because a dll > is missing ;). I certainly know that Oracle, Paradox & co. have been > established as standard. But I think a new small&simple database > solution would help developers worldwide enormously. > Alex
> > <<Anthony Paul Cavalcanti Ortiz: > > I'm a Delphi 4 programmer and am in the process of creating a BDE > > replacement engine. I would like to know of any sites where I can get > > ANY info of the following : > > 1) Database design/programming tips. > > Well, concider this posting a database design tip in the Delphi/VCL context. > > << > > 2) The latest in database performance/storage theories, optimizations, etc.. > > 2) Algorithms used for storing records. > > 3) Algorithms used for indexes. > > I really believe that the best reason for creating a BDE replacement
including a database engine Quote: > > would be to achieve a behaviour different from the BDE. If you want a square, traditional > > cursor-based relational database, it's just not worth the time creating
another one. Personally, I Quote: > > would never use a shareware db-engine unless I needed something
different from the regular ones. Quote: > > I've been checking out a few of them, and I haven't found a good one
yet. OK, the BDE isn't Quote: > > brilliant, but it is not a disaster compared to the rest of the world of
traditional databases. Quote: > > The choice of a DB engine is an Important one, because all concepts are
full of compromises, trading Quote: > > speed for security, fast read/write for disk space & memory, or the
other way around. I suggest that Quote: > > you study one small file-based database and one SQL-server to make a
decision about what level of Quote: > > functionality you want, and study the DBTABLES.PAS unit and the
BDE32.HLP to see how things are done Quote: > > on the application side. > > << > > 4) How to create a BDE replacement such that I can use my engine in > > place of the BDE and possibly retain use of the data aware components > > that Delphi supplies? In other words, I want people to be able to use > > the data aware components with it such as TDBGrid, TDBMemo, TDBEdit, > > etc... > > This locks you to creating a cursor-based database, because the
interface for the DB-controls are Quote: > > designed for such. In short - create an equivalent to most parts of the
BDE API, and create a Quote: > > modified DBTABLES unit (renamed, of course). > > <<The info I need would pertain to creating a small to medium databases, > > not the Interbase, Oracle or Sybase type of monstrous databases.>> > > On my 233MHz Laptop I run Oracle server on NT Workstation 4.0 starting
the NT Server and Oracle. Quote: > > Startup takes about 2 minutes. On my 3.2 Gb HDD I have 2 small company
databases, MS Office, an Quote: > > additional Win95, 4 Delphi versions and a lot of projects. I don't quite understand what is > > monstrous about that size ? MS Word uses more RAM than Oracle, and
Delphi takes longer to load. The Quote: > > only monstrous about those is the price... > > I believe you would have quite a job outperforming Paradox or Oracle. > > IMHO, the most important feature missing in network-enabled databases
from Paradox to oracle is that Quote: > > they don't provide a messaging service to notify other users when data
changes in the database. If Quote: > > you implement this functionality, even I would concider taking a look at such a concept.. > > <<ANY help would be MUCH appreciated, even if it's some source code, an > > article, a link to a web page, a good DB book, etc...>> > > The book "Using Delphi 3" by Miller, Powell, et al. described how to
create a custom dataset with Quote: > > Delphi. > > I'm afraid this was almost 100% discouraging. OK, it might be fun
creating a datbase engine. It's a Quote: > > hell of a lot of work, and you'll learn a lot. But I don't see how these
efforts could ever pay off Quote: > > unless you really need something different from the traditional Relational DB's. > > Good luck, anyway ! > > -- > > Bjoerge
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Wed, 18 Jun 1902 08:00:00 GMT |
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Bj?rge S?the #5 / 25
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Programming a database, any info?
<<Alexander Mueller: What I dont understand is that why database systems must be so complexe and difficult. What shall a database do? It should store data!
In the simplest fashion, yes. If you go 10 years back in pascal programming, most apps using what you would call a database would store their data in native format. It is quite a piece of work writing this, so it's no surprise database engines got into nearly every data-storing app over the last 10 years. Of course, it is fashion, as well. Today you would seem unprofessional storing data in native file structure. Even if it's better, and if noone really needs the database stuff in the app. The database does more than just storing data. It creates and maintains record structures, indexing, interprets SQL, joins tables, encrypts, password-protects, manages multiple users (IMHO one of the best reasons to choose a database), filters data... In the long run, a simple database could cause more work if too simple. The good thing about, say an Oracle Server, is that you may do almost anything you could think of, once you have got it up and running. A good example of the opposite is the ASCII driver of the BDE with it's limited functionality (well, it's not that clever to use this one with all the BDE stuff-overhead), it's only capable of satisfying very simple demands. << But ifyou use the BDE you need thousends of dlls. Why? Could this not be easier done? Look at Delphi. To access a database you need a TTable, a TDataSet and special database controls. And all this just to use "a few" datasets. But then the people are wondering when the exe file is as large as a 10 gb hd ;) and when the app doesnt work just because a dll is missing ;).
Yes, the dll stuff is no piece of cake. Borland should concider a model where only 1 dll was necessary to run a Database, even if this means you'll loose the ability to access different database engines from the application. They did not succeed in creating an open solution, after all, since database-specific stuff is to be hard-coded into the app. I would guess that less than 5%, maybe more like 1%, of datbase-apps written in Delphi are written to handle more than one datbase engine. <<I certainly know that Oracle, Paradox & co. have been established as standard. But I think a new small&simple database solution would help developers worldwide enormously.
I agree in one aspect of your argumantation: The data-storage and manpulation via controls should be possible without the overhead of the BDE. What about object-storage functionality support ? All applications do data mainpulation, and most application store data. In the VCL, you have nothing in between BDE and the TStrings.LoadFromFile. It would be possible, of course, to use the TPersistent streaming to create a data storage. We need some generic object persistence mechanism, like the TPersistent, but most of all: data-aware controls to be used with it ! Then storage could be designed simple or complex as wished. -- Bjoerge
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Wed, 18 Jun 1902 08:00:00 GMT |
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Peter Nol #6 / 25
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Programming a database, any info?
On Tue, 13 Jul 1999 02:27:43 +0200, "Bj?rge S?ther" Quote:
>>I really believe that the best reason for creating a BDE replacement including a database engine >>would be to achieve a behaviour different from the BDE. If you want a square, traditional
Bj?rge you are correct in a lot of what you say but the bit that annoys me with the BDE is that I have a 230K program that needs 3.6M of BDE stuff included in the Installation package. That takes it from a two minute download to a 20 minute from our web site. Often there are a lot of applications that just don't need SQL or even a table structure with cross-linking etc etc. I for one would jump at a BDE replacement for some apps. Specially if it only added about 100K to my finished project. I have a customer using just such an app with the BDE. I could easily have used a flat-file database as the DB-needs of the project are very basic indeed. I could use FlashFiler which is supposed to be a drop in for the BDE but TurboPower's tech support absolutely stinks. So it will be a long time before I consider buying **anything** from them again. There is one other I know of from Elevate software that I believe is a drop in, well almost and I may just mail them the money. The bottom line is I think there is a need for a compact flat-file database for a lot of applications. If it integrates with the data-aware components even better, but they carry substantial overhead too. Stick with it Anthony! Regards, Peter Nolan CEO Nolan Innovation Inc. ********************************* http://aluminator.tierranet.com Ph: (520) 772-9730 Cellular: (520) 713-7016 Fax: (520) 772-9839 *********************************
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Wed, 18 Jun 1902 08:00:00 GMT |
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Anthony Paul Cavalcanti Orti #7 / 25
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Programming a database, any info?
Quote: > I really believe that the best reason for creating a BDE replacement including a database engine > would be to achieve a behaviour different from the BDE. If you want a square, traditional > cursor-based relational database, it's just not worth the time creating another one. Personally, I > would never use a shareware db-engine unless I needed something different from the regular ones. > I've been checking out a few of them, and I haven't found a good one yet. OK, the BDE isn't > brilliant, but it is not a disaster compared to the rest of the world of traditional databases.
The reason I'm looking to do one for myself is the following : 1) knowledge/experience. 2) the BDE installation is a nightmare. 3) I need it to compile into my existing exe. 4) It has to be small. Quote: > <<The info I need would pertain to creating a small to medium databases, > not the Interbase, Oracle or Sybase type of monstrous databases.>> > On my 233MHz Laptop I run Oracle server on NT Workstation 4.0 starting the NT Server and Oracle. > Startup takes about 2 minutes. On my 3.2 Gb HDD I have 2 small company databases, MS Office, an > additional Win95, 4 Delphi versions and a lot of projects. I don't quite understand what is > monstrous about that size ? MS Word uses more RAM than Oracle, and Delphi takes longer to load. The > only monstrous about those is the price...
And the reason the price is monstrous is because so much functionality that the *typcial* programmer that needs to use a DB every so often doesn't use. That's why I don't want to make a "monstrous" engine, just something simple that will do the job. Quote: > I believe you would have quite a job outperforming Paradox or Oracle.
I don't think so. I've compared the BDE to the following BDE replacements : DBISAM, Topaz and Halcyon. I created identical 100,000 record tables and populated them with the same data. I performed the same benchmarks (filtering, reading, writing, going from BOF to EOF, etc...) on each one of them in the same manner and the results were surprising. DBISAM and Topaz were disappointing, the BDE was fast but Halcyon was the fastest of the bunch, and pretty good margin faster than the BDE!!! It also compiles into an executable and has a footprint of about 250k. I switched to the Halcyon engine at my job and 1) It's FAST!, 2) it's small, 3) it compiles into an exe and 4) NO BDE INSTALLATION HASSLES!!! Quote: > IMHO, the most important feature missing in network-enabled databases from Paradox to oracle is that > they don't provide a messaging service to notify other users when data changes in the database. If > you implement this functionality, even I would concider taking a look at such a concept..
That's interesting, would you give me an example or two of what you mean? Quote: > The book "Using Delphi 3" by Miller, Powell, et al. described how to create a custom dataset with > Delphi.
Thanks! Quote: > I'm afraid this was almost 100% discouraging. OK, it might be fun creating a datbase engine. It's a > hell of a lot of work, and you'll learn a lot. But I don't see how these efforts could ever pay off > unless you really need something different from the traditional Relational DB's. > Good luck, anyway ! > -- > Bjoerge
Thanks Bjoerge, any input at all is welcome, and I appreciate your help. Apparently criticism is not held in very high regard but I believe it to be an essential ingredient in discussions, so I welcome it. Any other thoughts would be appreciated! Anthony p.s. Give Halcyon a try, it's FAST and its filtering mechanism is nice! A company called griffin makes it I think...
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Wed, 18 Jun 1902 08:00:00 GMT |
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Bj?rge S?the #8 / 25
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Programming a database, any info?
<<Peter Nolan: Bj?rge you are correct in a lot of what you say but the bit that annoys me with the BDE is that I have a 230K program that needs 3.6M of BDE stuff included in the Installation package.
It's so if you distribute all of the standard BDE. For a Paradox DB, you'll need only about 1.2Mb of driver DLL's. Maybe it's against Borland guidelines, but I wouldn't care too much. It's silly to force someone to distribute dBase drivers with a Paradox database. << Often there are a lot of applications that just don't need SQL or even a table structure with cross-linking etc etc. I for one would jump at a BDE replacement for some apps. Specially if it only added about 100K to my finished project. I have a customer using just such an app with the BDE. I could easily have used a flat-file database as the DB-needs of the project are very basic indeed.
IMHO, you're not talking about a BDE replacement. You should concider using a text-file based TDataSet descendant with no need for special setup or dlls. I mentioned a book with sample code on such a dataset. But of course, if someone has made a component or suite - go for it ! <<The bottom line is I think there is a need for a compact flat-file database for a lot of applications. If it integrates with the data-aware components even better, but they carry substantial overhead too.>> Yeah, maybe...I wouldn't wait for Borland to do so...The sizes of everything over there keep growing... -- Bjoerge
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Wed, 18 Jun 1902 08:00:00 GMT |
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Robert Kapla #9 / 25
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Programming a database, any info?
Quote: > I for one would jump at a BDE replacement for some apps. Specially if > it only added about 100K to my finished project. I have a customer > using just such an app with the BDE. I could easily have used a > flat-file database as the DB-needs of the project are very basic > indeed.
The BDE is flawed because it has to be all things to all people. Look at DBISAM if you want a simple, no frills, fast small desktop database. If you use client server, there are native interfaces for most of the major database products. Or use ODBC. As somebody noted in this thread, there are very few programs that require using multiple databases. Hard enough to get just one working right, anyway. Robert
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Wed, 18 Jun 1902 08:00:00 GMT |
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Bj?rge S?the #10 / 25
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Programming a database, any info?
<<Anthony: The reason I'm looking to do one for myself is the following : 1) knowledge/experience. 2) the BDE installation is a nightmare. 3) I need it to compile into my existing exe. 4) It has to be small.
1) A *very* good reason, even if you chose not to use your own, you'd learn a lot about working with databases... 2) It's not that bad if you do it yourself (find out what .dll's are used, what registry entries are needed, etc). And - it is possible to do the installation from the .EXE itself. But- of course, I understand you disliking BDE installation - I've been into it for 3 years now. Then it's easy...;^D << Quote: > I believe you would have quite a job outperforming Paradox or Oracle.
I don't think so. I've compared the BDE to the following BDE replacements : DBISAM, Topaz and Halcyon. I created identical 100,000 record tables and populated them with the same data. I performed the same benchmarks (filtering, reading, writing, going from BOF to EOF, etc...) on each one of them in the same manner and the results were surprising. DBISAM and Topaz were disappointing, the BDE was fast but Halcyon was the fastest of the bunch, and pretty good margin faster than the BDE!!! It also compiles into an executable and has a footprint of about 250k. I switched to the Halcyon engine at my job and 1) It's FAST!, 2) it's small, 3) it compiles into an exe and 4) NO BDE INSTALLATION HASSLES!!!
I have downloaded the Halcyon database engine and I'm now about to test it. Thanks for the tip ! << Quote: > IMHO, the most important feature missing in network-enabled databases from Paradox to oracle is that > they don't provide a messaging service to notify other users when data changes in the database. If > you implement this functionality, even I would concider taking a look at such a concept..
That's interesting, would you give me an example or two of what you mean?
In a multi-user environment you'd like to receive a notification from the database server whenever data was changed in the database. Today you'll have to refresh the data manually from every client, not knowing if anything has happened at all. The way I've been dealing with this is to create a separate table storing the current update serialno for each dataset, so that a client can open this table, compare to the existing serialno's and refresh the data if a higher no is encountered. A much better solution would be if the server itself broadcasted a message to all loggedon clients that changes so and so has occurred. then the clients could decide for themselves whether to reload or not. Actually, a beautiful Client/Server concept could be created where the server and the clients were actually *talking* together. Where bandwidth is a problem (quite usual), The server could broadcast data rather than having all clients asking for the same data.. A small service app with say 100 clients could be run with small bandwidth requirements using sophisticated caching/version control/packing(zipping). OK, this was a bit far, maybe, but the notification is important ! It should be possible to use this concept (optionally, of course) for file-based db's as well. Of course, the file couldn't send a message, but it could store data versions easy accessible for all other clients upone each change. -- Bjoerge
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Wed, 18 Jun 1902 08:00:00 GMT |
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Tim Youn #11 / 25
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Programming a database, any info?
Robert, << Look at DBISAM if you want a simple, no frills, fast small desktop database. >> Geez Robert, I thought we had at least a couple of frills. ;-) Tim Young Elevate Software www.elevatesoft.com
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Wed, 18 Jun 1902 08:00:00 GMT |
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Steve Koters #12 / 25
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Programming a database, any info?
On Wed, 14 Jul 1999 00:17:44 +0200, "Bj?rge S?ther"
[...] Quote: >It's so if you distribute all of the standard BDE. For a Paradox >DB, you'll need only about 1.2Mb of driver DLL's. Maybe it's >against Borland guidelines, but I wouldn't care too much. It's >silly to force someone to distribute dBase drivers with a Paradox >database.
[...] This is does not contradict BDE redistribution requirements stipulated by Borland. It is discussed in section 3.3 "Partial BDE Installs" of the text file BDEDEPLOY.TXT, found in the main BDE directory. _/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/ Steve Koterski "Television is a medium because anything well done Felton, CA is rare." -- Fred Allen (1894-1956)
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Wed, 18 Jun 1902 08:00:00 GMT |
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Anthony Paul Cavalcanti Orti #13 / 25
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Programming a database, any info?
Quote: > I have downloaded the Halcyon database engine and I'm now about to test it. Thanks for the tip !
No problemo! Quote: > In a multi-user environment you'd like to receive a notification from the database server whenever > data was changed in the database. Today you'll have to refresh the data manually from every client, > not knowing if anything has happened at all. The way I've been dealing with this is to create a > separate table storing the current update serialno for each dataset, so that a client can open this > table, compare to the existing serialno's and refresh the data if a higher no is encountered. A much > better solution would be if the server itself broadcasted a message to all loggedon clients that > changes so and so has occurred. then the clients could decide for themselves whether to reload or > not. Actually, a beautiful Client/Server concept could be created where the server and the clients > were actually *talking* together. Where bandwidth is a problem (quite usual), The server could > broadcast data rather than having all clients asking for the same data.. A small service app with > say 100 clients could be run with small bandwidth requirements using sophisticated caching/version > control/packing(zipping). > OK, this was a bit far, maybe, but the notification is important ! It should be possible to use this > concept (optionally, of course) for file-based db's as well. Of course, the file couldn't send a > message, but it could store data versions easy accessible for all other clients upone each change.
That would be very useful. I don't see why this would be a big deal to implement, why haven't they done so? cul8r allig8r! Anthony
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Wed, 18 Jun 1902 08:00:00 GMT |
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Bj?rge S?the #14 / 25
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Programming a database, any info?
<<Steve Koterski: Quote: >Bjoerge Saether: >It's so if you distribute all of the standard BDE. For a Paradox >DB, you'll need only about 1.2Mb of driver DLL's. Maybe it's >against Borland guidelines, but I wouldn't care too much. It's >silly to force someone to distribute dBase drivers with a Paradox >database.
This is does not contradict BDE redistribution requirements stipulated by Borland. It is discussed in section 3.3 "Partial BDE Installs" of the text file BDEDEPLOY.TXT, found in the main BDE directory.
That's good, and I withdraw my somewhat agressive statement. The statement (that you have to distribute it all) has been repeated so many times that I took it for for the truth. So - I'm no criminal ! Good ! ;^D) -- Bjoerge
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Wed, 18 Jun 1902 08:00:00 GMT |
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Steve Koters #15 / 25
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Programming a database, any info?
On Thu, 15 Jul 1999 00:54:04 +0200, "Bj?rge S?ther"
[...] Quote: >That's good, and I withdraw my somewhat agressive statement. The >statement (that you have to distribute it all) has been repeated >so many times that I took it for for the truth. So - I'm no >criminal ! Good ! ;^D)
Criminal?! Just the opposite. You're spreading correct information. Where I come from, that's considered a Good Thing(TM). _/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/ Steve Koterski "Television is a medium because anything well done Felton, CA is rare." -- Fred Allen (1894-1956)
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Wed, 18 Jun 1902 08:00:00 GMT |
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