How to obtain a correct number of records in TpFIBDataSet?
Fast, flexible and high-performance component library for Delphi, C++ Builder and Kylix intended for work with InterBase and Firebird using Direct InterBase API.
|
Question: How to obtain a correct number of records in TpFIBDataSet?
Answer: FIBPlus works with the server at the level of SQL queries. The server does not return the record number to the client after the SELECT query, because all the records are retrieved one after another by the Fetch method.
In practice we know the number of records fetched only when the server reports that there are no more records in the query result after the regular Fetch.
The simplest thing you can do to obtain the correct number of records in the TpFIBDataSet is to use the poFetchAll option. After opening the query you should check the RecordCount value (it will be correct) or to use the psAskRecordCount option. If psAskRecordCount = True, then after opening SelectSQL TpFIBDataSet will automatically execute a supplementary query "SELECT count(*)" in order to make the server report about the record number.
This mechanism does not guarantee correct work because the COUNT() use is restricted by InterBase/Firebird features.
Besides sometimes FIBPlus cannot convert the main query from SelectSQL (it can be very complex) into a simple query which will only get the record number.
Such a behaviour is common for any InterBase/Firebird library.
We are a small software company with thousands of customers delivering comany wide systems including accounting, logistics, e-commerce, POS, sales etc etc. Several years ago, when we were still a very small company, we used Delphi 3 and Paradox combined with BDE. As our system (and customer base) grew I decided to switch to Delphi 5 and Interbase. Being a huge improvement over Delphi 3 and Paradox, I encountered numerous problems with IBX: memory leaks, performance issues and other problems. Borland was not to be bothered: IBX was provided "as is" and no support was avaliable. Not being very eager to use third party components with Delphi at first, I decided to give FIBPlus a try. At once all problems where gone: no more memory leaks and performance was very consistent.
But the real advantage of switching to FIBPlus came with the upgrade to D2005: after upgrading there were some problems with the new FIBPlus version. After emailing the problem I received an update within an hour! And this was at 11 pm! A few other (smaller) errors where handled in the same way.
Our motto is: software is as good as its support. And support of Devrace is just great!
Just a little indication of our FIBPlus use: all our software runs 100% on FIBPlus. Our customers have a total of aprox. 4.800 Firebird databases in production, with a combined size of over 130TB and over 80 million transactions a day. Every
day. And FIBPlus has not failed a single transaction. Not once. There is, however, one (minor) drawback in using FIBPlus: while debugging an application which uses and invalid SQL instruction, de Delphi Debugger returns to the FIBPlus code instead of to our calling code (where the actual error comes from), thereby complicating de debug proces a little. But that is a very small price to pay for a otherwise brilliant third party solution! >>
Bas Jordans JorSoft Ltd
