[OSM-dev] Analysis of database point fields vs returned query records
Nick Hill
nick at nickhill.co.uk
Sun Apr 9 15:33:15 BST 2006
Analysis of database field size vs points returned performance.
I have prepared tables of query timings based on a 1M point field and a
10M point field using MySQL4.0 debian stable on an AMD Sempron 32 bit
2200 512M ram. These timings are for constraints on a table only
containing the lat/lon.
These figures were achieved by first calculating a random point on the
point field, then, assuming an even density distribution of points, an
area was calculated to give the shown number of points. A query was then
run for that calculated area. The time for 25 queries was summed then
divided by 25, to give a mean average. The largest query size was
initially run repeatedly until no appreciable reduction in query time
was observed, to ensure caches were full before figures were taken. The
Limit function was not used,
1 million point field
Records | Time
50 0.010s
100 0.013s
200 0.017s
400 0.05s
800 0.05s
1600 0.06
3200 0.077
6400 0.094
12800 0.12s
25600 0.15s
10 Million point field
50 0.08s
100 0.1s
200 0.12s
400 0.16s
800 0.21s
1600 0.28s
3200 0.40s
6400 0.552
12800 0.80s
25600 1.20s
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