BorlandTalk.com Borland discussion newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  TCustomClientDataset.GetRecord -> "GetSequenceNumber" and db          BorlandTalk.com Forum Index -> Delphi Databases (dbExpress) View previous topic :: View next topic   Author Message Martijn Tonies Guest Posted: Tue Sep 12, 2006 7:37 pm    Post subject: TCustomClientDataset.GetRecord -> "GetSequenceNumber" and db Hi, Righto, this will be a "how do the internals work" post. A customer asked about an exception he was getting with ApplyUpdates when using our dbExpress driver for Firebird, while he wasn't getting this error with the InterBase driver. Well, here's the thing -- TCustomClientDataset.GetRecord calls, after .Append(ing) a record and calling ApplyUpdates, a method from its "DSCursor" it has, here: function TCustomClientDataSet.GetRecord(Buffer: PChar; GetMode: TGetMode; DoCheck: Boolean): TGetResult; (get's called from .Resync) .... .... case Status of DBERR_NONE: begin if (AggFields.Count > 0) and AggregatesActive then GetAggFieldData(Buffer); with PRecInfo(Buffer + FRecInfoOfs)^ do begin BookmarkFlag := bfCurrent; GetSequenceNumber(DWord(RecordNumber)); GetRecordAttribute(Attribute); end; .... .... For the InterBase driver, the call to GetSequenceNumber returns a value equal to the number of rows, while for our driver it returns "1". This makes the RecordNumber the same as another record number and subsequent calls to Append and ApplyUpdates fail with a Key Violation (not coming from the driver, but from within midas.dll!!!). I have _no idea at all_ why this returns a different value for our driver. I have _no idea_ if this call (from the DSCursor) calls some method in the driver, it doesn't go into our driver, but it could be that has some cause beyond my knowledge. Could someone from Borland, probably someone who knows the midas.dll internals, shed a light on this?? -- Martijn Tonies Database Workbench - tool for InterBase, Firebird, MySQL, NexusDB, Oracle & MS SQL Server Upscene Productions http://www.upscene.com My thoughts: http://blog.upscene.com/martijn/ Database development questions? Check the forum! http://www.databasedevelopmentforum.com Back to top Craig Stuntz [TeamB] Guest Posted: Thu Sep 28, 2006 9:31 pm    Post subject: Re: TCustomClientDataset.GetRecord -> "GetSequenceNumber" an Martijn Tonies wrote: Quote: I have _no idea_ if this call (from the DSCursor) calls some method in the driver, it doesn't go into our driver, but it could be that has some cause beyond my knowledge. It can't. Briefcase mode would never work, otherwise. You can prove this to yourself. Write a three-tier project using sockets. Write an intercept library that just logs what comes over the pipe (or there's an intercept demo which you can just use as-is). Put a breakpoint on the intercept. You'll get nothing. I suspect that the behavior you're seeing has to do with some value which came from the driver earlier, most likely when the data was fetched in the first place. Note that you can look at the data packets directly in Delphi code and even do a binary diff on them. You could set up an app which fetched identical data from identical DBs and reported the difference between the packets. That might give you a clue as to where to look. -- Craig Stuntz [TeamB] · Vertex Systems Corp. · Columbus, OH Delphi/InterBase Weblog : http://blogs.teamb.com/craigstuntz Borland newsgroup denizen Sergio González has a new CD of Irish music out, and it's good: http://tinyurl.com/7hgfr Back to top Martijn Tonies Guest Posted: Fri Sep 29, 2006 8:11 am    Post subject: Re: TCustomClientDataset.GetRecord -> "GetSequenceNumber" an Quote: I have _no idea_ if this call (from the DSCursor) calls some method in the driver, it doesn't go into our driver, but it could be that has some cause beyond my knowledge. It can't. Briefcase mode would never work, otherwise. You can prove this to yourself. Write a three-tier project using sockets. Write an intercept library that just logs what comes over the pipe (or there's an intercept demo which you can just use as-is). Put a breakpoint on the intercept. You'll get nothing. I suspect that the behavior you're seeing has to do with some value which came from the driver earlier, most likely when the data was fetched in the first place. Note that you can look at the data packets directly in Delphi code and even do a binary diff on them. You could set up an app which fetched identical data from identical DBs and reported the difference between the packets. That might give you a clue as to where to look. Hello Craig, Thanks for the response -- but you've got me puzzled here :-) How can I do what you're talking about? -- Martijn Tonies Database Workbench - tool for InterBase, Firebird, MySQL, NexusDB, Oracle & MS SQL Server Upscene Productions http://www.upscene.com My thoughts: http://blog.upscene.com/martijn/ Database development questions? Check the forum! http://www.databasedevelopmentforum.com Back to top Craig Stuntz [TeamB] Guest Posted: Fri Sep 29, 2006 5:34 pm    Post subject: Re: TCustomClientDataset.GetRecord -> "GetSequenceNumber" an Martijn Tonies wrote: Quote: How can I do what you're talking about? Which thing? The intercept, or comparing the data packet? -- Craig Stuntz [TeamB] · Vertex Systems Corp. · Columbus, OH Delphi/InterBase Weblog : http://blogs.teamb.com/craigstuntz How to ask questions the smart way: http://www.catb.org/~esr/faqs/smart-questions.html Back to top Martijn Tonies Guest Posted: Fri Sep 29, 2006 10:13 pm    Post subject: Re: TCustomClientDataset.GetRecord -> "GetSequenceNumber" an Quote: How can I do what you're talking about? Which thing? The intercept, or comparing the data packet? Both :-) -- Martijn Back to top Craig Stuntz [TeamB] Guest Posted: Fri Sep 29, 2006 10:45 pm    Post subject: Re: TCustomClientDataset.GetRecord -> "GetSequenceNumber" an Martijn Tonies wrote: Quote: Which thing? The intercept, or comparing the data packet? Both Well, there's already an intercept demo in the Demos / DB / Midas folder which came with Delphi (I may have the folder name wrong; this is from memory. I don't think you really need to do this, since I can tell you what the result will be, but you might want to prove it to yourself. The data packet can be found at TCustomClientDataSet.Data. It's an OleVariant containing an array of bytes. You can iterate through the bytes one at a time to see where they differe. -- Craig Stuntz [TeamB] · Vertex Systems Corp. · Columbus, OH Delphi/InterBase Weblog : http://blogs.teamb.com/craigstuntz Everything You Need to Know About InterBase Character Sets: http://blogs.teamb.com/craigstuntz/articles/403.aspx Back to top Martijn Tonies Guest Posted: Mon Oct 02, 2006 8:29 pm    Post subject: Re: TCustomClientDataset.GetRecord -> "GetSequenceNumber" an Quote: Which thing? The intercept, or comparing the data packet? Both :-) Well, there's already an intercept demo in the Demos / DB / Midas folder which came with Delphi (I may have the folder name wrong; this is from memory. I don't think you really need to do this, since I can tell you what the result will be, but you might want to prove it to yourself. Hmm... can't find it anywhere. Could this be an "Enterprise" edition only demo project? Quote: The data packet can be found at TCustomClientDataSet.Data. It's an OleVariant containing an array of bytes. You can iterate through the bytes one at a time to see where they differe. Let me see what I can do ... I'm still surprised how this behaviour can be affected by a driver though. -- Martijn Tonies Database Workbench - tool for InterBase, Firebird, MySQL, NexusDB, Oracle & MS SQL Server Upscene Productions http://www.upscene.com My thoughts: http://blog.upscene.com/martijn/ Database development questions? Check the forum! http://www.databasedevelopmentforum.com Back to top Craig Stuntz [TeamB] Guest Posted: Mon Oct 02, 2006 8:48 pm    Post subject: Re: TCustomClientDataset.GetRecord -> "GetSequenceNumber" an Martijn Tonies wrote: Quote: Hmm... can't find it anywhere. Could this be an "Enterprise" edition only demo project? Could well be, as you don't get sockets without Enterprise and hence can't do that test without it. On my install it's in: C:\Program Files\Borland\BDS\4.0\Demos\DelphiWin32\VCLWin32\MIDAS\Intrcpt Quote: Let me see what I can do ... I'm still surprised how this behaviour can be affected by a driver though. Can't really say until I figure out what the problem is. The other thing you could do is compare the results of the calls into your driver with the results of the calls into the Borland drivers. You can pretty easily trace the arguments in and out of both drivers, even though you don't have source for the Borland driver. -- Craig Stuntz [TeamB] · Vertex Systems Corp. · Columbus, OH Delphi/InterBase Weblog : http://blogs.teamb.com/craigstuntz How to ask questions the smart way: http://www.catb.org/~esr/faqs/smart-questions.html Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         BorlandTalk.com Forum Index -> Delphi Databases (dbExpress) All times are GMT Page 1 of 1   Jump to: Select a forum C++ Builder Newsgroups----------------C++ BuilderC++ Builder (ActiveX)C++ Builder (Announcements)C++ Builder (Command Line Tools)C++ Builder DatabasesC++ Builder Databases (ADO)C++ Builder Databases (Desktop)C++ Builder Databases (InterBase Express)C++ Builder Databases (Multi-Tier)C++ Builder Databases (SQL Servers)C++ Builder (Graphics)C++ Builder (IDE)C++ Builder (Internet)C++ Builder (Internet Socket)C++ Builder (Internet Web)C++ Builder (Jobs)C++ Builder (Language)C++ Builder (Language C++)C++ Builder (Compatibility with MFC)C++ Builder (Native API)C++ Builder (Non-Technical)C++ Builder (Students)C++ Builder (Third Party Tools)C++ Builder (Upgrade)C++ Builder (VCL)C++ Builder (VCL Components Usage)C++ Builder (VCL Components Development)C++ Builder (VCL Usage)C++ Builder (WinAPI)C++ Builder Installation Delphi Newsgroups----------------Delphi (General)Delphi ActiveX Controls UsageDelphi ActiveX Controls DevelopmentDelphi As400Delphi DatabasesDelphi Databases (ADO)Delphi Databases (dbExpress)Delphi Databases (Desktop)Delphi Databases (InterBase Express)Delphi Databases (Multi-Tier)Delphi Databases (SQL Servers)Delphi DeploymentDelphi GraphicsDelphi IDEDelphi InternationalizationDelphi InternetDelphi Internet Isapi-WebBrokerDelphi Internet WebSnapDelphi Internet WinsockDelphi JobsDelphi Language BASMDelphi Language ObjectPascalDelphi Model Driven Architecture (General)Delphi Model Driven Architecture (Third Party)Delphi MultimediaDelphi Native APIDelphi Non-TechnicalDelphi ObjectPascalDelphi OLE AutomationDelphi OO designDelphi OpenToolsAPIDelphi Reporting-ChartingDelphi RTLDelphi StudentsDelphi TeamSourceDelphi Thirdparty ToolsDelphi Thirdparty Tools (General)Delphi Thirdparty Tools (IntraWeb)Delphi Thirdparty Tools (RaveReports)Delphi UpgradeDelphi VCLDelphi VCL ComponentsDelphi VCL Components UsingDelphi VCL Components WritingDelphi WebServices SOAPDelphi WinAPIDelphi XMLDelphi Installationcomp.lang.pascal.delphi.components.misccomp.lang.pascal.delphi.components.usagecomp.lang.pascal.delphi.components.writingcomp.lang.pascal.delphi.databasescomp.lang.pascal.delphi.misccomp.sources.delphi JBuilder Newsgroups----------------JBuilderJBuilder AnnouncementsJBuilder Applet IssuesJBuilder As400JBuilder CompilerJBuilder CORBA/RMIJBuilder DatabasesJBuilder DB SwingJBuilder DebuggerJBuilder DeploymentJBuilder DocumentationJBuilder EnterpriseJBuilder HandheldJBuilder IDEJBuilder JavaJBuilder JavaAPIJBuilder Java LanguageJBuilder Java SwingJBuilder Java BeansJBuilder Java Beans UsageJBuilder Java Beans DevelopmentJBuilder JBCLJBuilder JDataStoreJBuilder JobsJBuilder LinuxJBuilder MacintoshJBuilder & MobileSetJBuilder MultiLingual AppsJBuilder Non-TechnicalJBuilder OpenToolsJBuilder Servlets (JSP)JBuilder StudentsJBuilder Team DevelopmentJBuilder Thirdparty ToolsJBuilder UpgradeJBuilder Installation InterBase Newsgroups----------------InterBaseInterBase Bug DiscussionInterBase GeneralInterBase IBConsoleInterBase OpenSourceInterBase ReplicationInterBase SQLInterBase ThirdpartyInterBase Installation Miscellaneous Borland Newsgroups----------------AppCenterAppServerEnteraVisiBroker  You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum Powered by phpBB © 2001, 2006 phpBB Group SEO toolkit © 2004-2006 webmedic.