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| Paper: |
A Simple Survey of Cross-Matching Methods |
| Volume: |
523, Astronomical Data Analysis Software and Systems XXVIII |
| Page: |
551 |
| Authors: |
Fan, D.; Xu, Y.; Han, J.; Li, C.; He, B.; Tao, Y.; Cui, C. |
| Abstract: |
In order to find a practicable method to build an online cross-matching service, we test several index and search methods. Indexing methods include the directly matching, HEALPix based matching and zones algorithm. Sorted list and several search trees are also inspected, e.g., Binary Search Tree, Red-Black Tree, B-Tree. From this survey, we can see that HEALPix based Binary Search on sorted arrays is the fastest and simple way to cross-match in memory, and the environment is easily restored from hardisk. If there are two unsorted catalogs on disk, a red-black balance tree with HEALPix indices would be a good choice. But when the catalog is too big to cache in memory, the memory-hardisk-swapping significantly slows down the efficiency. The key is keeping more points in the memory and do the Binary Search. Not only the speed to cross-match, how to efficiently exporting the rest data columns in catalogs is also considered. A cross-match web service built on these method is released. |
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