Re: Informix c-isam ==> esql-c conversion ?

I sent a message to c.d.i on Thursday (16 January 1997) with the subject "Re: Informix file to ASCII file??" about converting C-ISAM files to SE (Standard Engine, accessible via ESQL/C), which covers many points you need to know, but from a rather different angle. In general, your C-ISAM files are unlikely to be directly acceptable as SE files because although all SE data files are C-ISAM files, most C-ISAM files are not valid as SE files unless they were specifically created with SE-compatability in mind. The overhead by switching will depend on the extent to which you do a direct conversion of the C-ISAM calls into SQL calls, versus rewriting the application to make use of SQL to select the data from multiple tables at one time. If you do not rewrite the application to exploit the capabilities of SQL, then performance will suck (suck lots of CPU cycles out of the fastest machine you care to throw at the problem). If you do rewrite appropriately, you may see a small performance degradation, or even a performance improvement. Any loss of performance is usually compensated by the fact that the data is more secure, amongst other things. Yours, Jonathan Leffler (johnl@informix.com) #include <disclaimer.h> >From: Douglas Mick <dmick@va.wagner.com> >Date: Mon, 20 Jan 1997 10:12:39 -0500 >X-Informix-List-Id: <news.32786> > >Our company has used c-isam to build proprietary databases. I recently >mentioned the possibility of using esql-c instead of direct c-isam >database creation / access functions. Along this line, I have several >questions : > > 1. How much overhead might be introduced by switching > over to esql-c in place of c-isam ? > > 2. Would our proprietary databases that already exist > be easily converted to esql-c format ?