SAI VO . ... SAI CAS . ... Access . ... We present the results of the development of Sternberg Astronomical Institute Catalog Access Services (SAI CAS) project - the first and the only project in Russia, which provides online access to the major astronomical catalogues and different services on top of them. ... SAI CAS is an open-source implementation of the general Catalogue access service (influenced by SDSS CAS CASjobs project), based on original algorithms and open-source software. ... SAI MSU | ...
Hide Zen home . ... Index . ... Do we really need them for database indexing ? ... We need simple numbering scheme, so that for any given point we could easily calculate the number of "pixel", this is what HealPix provides and lacks HTM. ... During Rtree queries the number of index blocks read is several times greater than during Q3C queries. ... But in Q3C scheme, as we showed before, the circle is segmented, so we extract from the database only a few percents more data than occur in the circle. ...