Hi Stephen I apologise for my overly simplistic statement. MasterMap data can be translated into ESRI shape files, so in a literal sense my statement is misleading.
However even with Landline data performance of SHP versus MI MAP was poor and MasterMap is the "straw that breaks the camels back" ( in my opinion!). The amount of geometry to be read is virtually double with MasterMap as the line geometry is delivered a second time as polygons. ( The attribute data is less important. Unless producing thematics this does not need to be read at draw time. Even for thematics you only need to read records for objects that intersect the screen). This doubling of data presents little problem to MapInfo MAP format because of the way the RTREE index works. MapInfo only reads from the file data contained in blocks (MBRS) that intersect the screen. If there were 100 objects on the screen with Landline there will now be approx. 200 and read time from the Map file will double from say 0.1 second to 0.2 second. The RTREE index is constantly reorganised so that MBRS adjacent on the ground are adjacent within the MAP file, so disk heads are not constantly jumping around at read time. In terms of "scaleability" MapInfo TAB (I think) is out in front. Basically it could cope with up to 20 times as much data for 1 extra block read. The secret lies in reorganisation of data at write time - the payback faster read time for redraws. With the native SHP,SHX file format the data is NOT rearranged so that objects adjacent on the ground are adjacent in the file. Every single MBR in the SHX file has to be compared with the Screen MBR. If it is on the screen then the full object contained in the SHP file will again be stored randomly ( stored in order added ) and disk access will be relatively slow compared to MapInfo as the heads will be jumping around rather than reading contiguously. So the whole SHX file needs to be read, if there are 4 million objects every MBR has to be read, and then the 200 on the screen will need to be read in full randomly ( rather than contiguously ) from the SHP file. At the recent OS MasterMap roadshows ESRI have only promoted solutions based on Oracle and use the complexity of MasterMap as the need for this, rather than explaining that SHP cannot cope. It is alarming to hear how much ESRI customers are paying for both hardware and software to introduce MasterMap ( in tens of thousands) whereas MapInfo customers have several choices of translators to native format AS WELL as spatial Oracle AND SQL server. I work for a MapInfo Premier Partner and could be accused of being biased. However I really believe even MapInfo themselves undervalue the performance they have in their native format and unfortunately have been happy to go along with the argument that MasterMap does need Oracle ( or Spatialware ). They are then on a level playing field against ESRI whereas competing on the desktop they were way out in front ( my opinion again). For me the "crown jewels" of MapInfo is the native format. So my earlier statement was very much a personal view but based on 24 months or so working with MasterMap and on statements made at the Ordnance Survey Roadshows. I think Paul was spot on in his statement that you only need powerful multi-user capability for data that is changing frequently and being updated from more than one source. This is not the case for most OS data, as they are the only source to supply updates. I do not think there is any fear of ESRIs position being undermined! I think the push to Oracle is winning and my views put me in the minority. I guess there's not a lot of money to be made in pushing solutions based on customers existing investment! Linux and MySQL are virtually free but how many LAs use that! "Best value" is perhaps not a good measure for LAs as our individual measure of value varies. For me storing GIS for free and viewing it with best performance is "Best value". It frustrates me how we waste the performance that Intel keeps giving us. MapInfos strength is best demonstrated when you see it running on a 486. One of my colleagues recently needed to reinstall Windows 95 on one of our "testing" platforms. Its running on a Pentium 90 and fires up quicker than XP on a 2 GHz Pentium. Thanks to "Moore's Law" I'm sure in the future we will be able to store GIS in the most inefficient of formats and still get instant response - but is that "Best value"? Hopefully my convictions explain my response to Paul's message. Regards Bob MapsByDesign.co.uk Quoting Stephen Dunn <[EMAIL PROTECTED]>: > Hello List, > > I see that in the Oracle Spatial thread, Bob of ByDesign mentioned that > > "MapInfo competition such as ESRI > shape files cannot cope with MasterMap." > > I didn't know this - Very interesting. > - Does anyone know why? > Is it simply the huge data volumes of MasterMap, or > is there another reason? > - Are other competitor products having trouble too? > > I would think that unless ESRI addresses this issue pretty > sharp-ish it's going to seriously undermine their position > in the UK. > > Stephen Dunn. > > > > > > > * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * > * > This email and any attachments with it are intended for the addressee only. > It may be confidential and may be the subject of legal and/or professional > privilege. > If you have received this email in error please notify the sender or > [EMAIL PROTECTED] > The content may be personal or contain personal opinions and cannot be taken > as an expression of the County Council's position. > Surrey County Council reserves the right to monitor all incoming and outgoing > mail. > Whilst every care has been taken to check this outgoing e-mail for viruses, > it is your responsibility to carry out any checks upon receipt. > * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * > * > > > --------------------------------------------------------------------- > List hosting provided by Directions Magazine | www.directionsmag.com | > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] > Message number: 10279 > > --------------------------------------------------------------------- List hosting provided by Directions Magazine | www.directionsmag.com | To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] Message number: 10286
