Hello, I am working on #6448 QGIS issue - Extremely slow shapefile reading over network. You can find my latest observations in http://hub.qgis.org/issues/6448#note-19
Long story short, OGR does not buffer I/O and Windows does not always cache network files. I have few questions for OGR developers: 1. Are there my OGR related notes in the issue comment correct? 2. Would it be possible to implement buffering in VSI? 3. Is it VSI cache (if VSI_CACHE_SIZE is set to some small number) suitable to be used as buffer? 4. Would it be possible to implement buffering or to extend VSI cache for writing (to allow editing)? 5. Have you considered to increase CHUNK_SIZE (currently 32768)? Where does that size comes from? I saw that XP is using 32768 but from what I have read, SMB1 block size limit was 64K but SMB2 should not have that limit. E.g. gvSIG 2.0.0 is using via its BigByteBuffer2 class block size 61440. Radim _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
