On Thu, 29 Oct 2009, Angel Pais wrote: Hi,
> Very interesting and usefull document, congratulations ! Thanks. I hope you will find it useful. > The section about dbfs and indexes limits is somewhat confusing to me. > Did I understood well that if you use NTX indexing you can have 2TB > tables while with CDX you can´t ? No. 1-st of all you mixed table and index size. Maximum table (DBF) size is independent without any relations to used index formats. By default maximum size for CDX, NTX and NSX indexes is 4GB and it's limit created by their internal formats. Small modification in this formats allows to increase the size but new indexes are not binary compatible and cannot be used by other languages if they not have such extensions (and they rather do not have them because I created them myself). I've implemented such extension so far only for NSX and NTX formats and it's enabled by default when 64bit locking is used. It move maximum index file size to 4TB. So far I haven't added this extension to CDX format. If I add it then it will increase maximum CDX file size to 2TB when standard page size is used. I can also add support for page size controlled by user and it will give additional maximum size improvement. Support for page size defined by user can be added to all index formats (NTX, NSX, CDX). Below it's text from xhb-diff.txt. If it's not clear enough then we can update it. > I guess this is only possible in Linux, right ? No. It's OS independent. Limits introduced by OS or FS (file system) are different thing and user should check what it maximal size for files stored on some file system accessed by some operating system. If they are smaller then they will reduce also Harbour programs just like any others which may want to create and/or manage larger files. If you are MS-Windows user then you should check limits for different MS-Windows (9x,ME,NT,W2K,XP,...) versions and used FS (FAT16,FAT32, NTFS, NTFS<N>, ... best regards, Przemek Maximal NTX file size for standard NTX files is 4GB and it's limited by internal NTX structures. Enabling 64bit locking in [x]Harbour change slightly used NTX format and increase maximum NTX file size to 4TB. The NTX format in [x]Harbour has also many other extensions like support for multitag indexes or using record number as hidden part of index key and many others which are unique to [x]Harbour. In practice all of CDX extensions are supported by NTX in [x]Harbour. The NSX format in [x]Harbour is also limited be default to 4GB but like in NTX enabling 64bit locking extend it to 4TB. It also supports common to NTX and CDX set of features. The CDX format is limited to 4GB and so far [x]Harbour does not support extended mode which can increase the size up to 2TB with standard page length and it can be bigger in all formats if we introduce support for bigger index pages. Of course all such extended formats are not binary compatible with original ones and so far can be used only by [x]Harbour RDDs though in ADS the .adi format is such extended CDX format so maybe in the future it will be possible to .adi indexes in our CDX RDD. Of course all of the above sizes can be reduced by operating system (OS) or file system (FS) limitations so it's necessary to check what is supported by environment where [x]Harbour applications are executed. _______________________________________________ Harbour mailing list Harbour@harbour-project.org http://lists.harbour-project.org/mailman/listinfo/harbour
