KEYWORDS

database, attribute table, driver

DESCRIPTION

MySQL database driver in GRASS enables GRASS to store vector attributes in MySQL embedded database without necessity to run MySQL server.

Driver and database name

GRASS modules require 2 parameters to connect to a database. Those parameters are 'driver' and 'database'. For MySQL embedded driver the parameter 'driver' should be set to value 'mesql'. The parameter 'database' is a full path to the directory where database tables are stored. The best place is a directory in the mapset. The directory must be created before use of the driver. In the name of database it is possible to use 3 variables:

 $GISDBASE - path to current GISBASE

 $LOCATION_NAME - name of current location

 $MAPSET - name of current mapset

Examples of connection parameters:
db.connect driver=mesql database='$GISDBASE/$LOCATION_NAME/$MAPSET/mysql'
db.connect driver=mesql database=/home/user1/db

Data types, indexes

For more information about supported data types and indexes see the documentation for MySQL (mysql) driver.

Database type

Because database closing was found very slow if InnoDB was used, the InnoDB storage is disabled by default (hardcoded '--skip-innodb' server option).

Note

The embedded server is started with hardcoded '--bootstrap' option to avoid warning about missing "mysql.time_zone_leap_second table". This can be fixed in future.

Troubleshooting: SQL syntax error

Attempting to use a reserved SQL word as column or table name will result in a "SQL syntax" error. The list of reserved words for MySQL can be found in the MySQL manual.

Credits

Development of the driver was sponsored by Faunalia (Italy) as part of a project for ATAC.

AUTHOR

Radim Blazek

Last changed: $Date: 2014-02-15 23:27:05 +0100 (Sat, 15 Feb 2014) $
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