Atlas Database

This page explains the internals of the database and gives some hints for user defined actions on the data.

Database Format

The database is based upon wxsqlite which is a wrapper around the SQLite 3 database.

Example

Start the command line tool and show a list of available tables.

~/.maitreya-7.0> sqlite3 geonames.db
SQLite version 3.6.22
Enter ".help" for instructions
Enter SQL statements terminated with a ";"
sqlite> .tables
admincodes atlas_ascii geonames
atlas countries geonames_aliases
atlas_alias featurecodes timezones
sqlite>

Import Location Data

The atlas database contains data from geonames.org. The source code distribution of Maitreya contains a perl script (src/atlas/geonames.pl) that can be used for user defined import or update of the atlas data.

Example steps

  • Open the script and download the referenced files from the geonames download area
  • There are several versions of the geonames data: cities with more than 1000 or 10,000 inhabitants, or the full data
  • Open the SQLite database with the command line tool
  • Execute the DDL file with table definitions (src/db_ddl.sql). The SQLite command is ".read"
  • Start the perl script
  • Set the new database file in Configuration/Atlas if necessary
  • Export can be done with the command ".output". The result will be similar to the default database script in src/geonames1000.sql

Filtering User Defined Entries

User defined changes of the database are marked internally. So a separate export of these records is possible.

The table "geonames" has a column "usercode" with values

  • 0: not modified
  • 1: entry was changed by the user
  • 2: entry was added by the user

Example

~/.maitreya-7.0> sqlite3 geonames.db
SQLite version 3.7.9 2011-11-01 00:52:41
Enter ".help" for instructions
Enter SQL statements terminated with a ";"
sqlite> select usercode,count(*) from geonames group by usercode;
0|123392
1|8
2|7
sqlite>

In the example 8 records were changed, 7 records were added.