Tests of the Starry 2MASS database

Testable objects:
XY-coordinates of Stars of the open database 2MASS.


The database contains 470,992,970 point objects of Starry Sky. Abbreviation 2MASS means “The survery of all the sky on a wavelength of 2 microns”.

The purpose of the 2MASS project is to scan the sky in infrared range. The scan was executed by means of two telescopes in north hemisphere (Arizona) and south hemisphere (Chile) in 1997-2001.

One of the tasks of the 2MASS project was to catalogue all discovered objects.

The project was financed by NASA (National Aeronautics and Space Administration) and NSF (National Science Foundation).

Testing has shown that the database contains hundreds of anomalies (defects). See Artifacts of the 2MASS database.


1. Number of Stars (all Starry Sky)

All sky

A density of Stars in some regions of the Milky Way can be 1000 times higher than a density of Stars in the most rarefied region of Starry Sky.
470,992,970
2. Size of the table of coordinates of Stars on hard disk

Table
3.5 GB
3. Size of the index of coordinates of Stars

Index
5.4 MB
4. The size of index related to the size of indexed coordinates of Stars (index was compressed to a half of its initial size) 0.15 %
5. Time of indexing coordinates of Stars 12 minutes
6. The size of RAM used by the shell program

Index
4.6 MB
7. The size of RAM buffers allocated to organize range queries 0.1 MB
8. The size of the total RAM allocated during queries is insignificant: the size of the shell program (4.6 MB) + the size of the unpacked index (9.8 MB) + the size of buffer (0.1 MB).

The entire database remains on the hard disk, RAM is free.

Index
4.6 + 9.8 + 0.1 = 14.5 MB
9. A speed of performance of range queries is very high. See video A tour to the 2MASS database. The video contains counters. real time

10. For comparison (on test computer):
Time of copying a 1.0 GB file to the same directory
1 min
11. For comparison (on test computer):
Time of compression a 1.0 GB file to format *.rar format
5 min 15 sec
12. For comparison (on test computer):
Time of compression a 1.0 GB file to format *.zip format
4 min 31 sec



Computer used in tests is a standard home desktop computer bought for $ 1000: Intel(R) Pentium(R) Dual CPU E2200 @ 2.20 GHz, 2.99 GB RAM.

Prior to generating the data, indexing and testing, there has been no preparation of the computer done nor has there been any disk defragmentation software used, i.e. the station was used in the current status "as is".

During test queries a disk space of the station was used up by 95 % (full size of disk space is 390 GB).

Platform: Microsoft Windows XP Professional, version 2002, Service Pack 2.

During the tests the computer was connected to the Internet, anti-virus system was active.

When saving the source base on a portable hard disk Seagate FreeAgent, the system works via USB-channel at approximately the same speed. Search time is the same as in case when the database is located on the hard disk.



Search Technology developed with support from FASIE
foundation formed by the Government of Russian Federation
Novosib-BIT LLC 2004 - 2017
Patented