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Full Discussion: Selective delete in SQL
Top Forums UNIX for Dummies Questions & Answers Selective delete in SQL Post 302772861 by cero on Wednesday 27th of February 2013 03:02:23 AM
Old 02-27-2013
There most likely is a way to find out what is in the first 100 mb of the file, but that is not how databases work. One reason database systems were invented is that you do not have to bother with this kind of things, so the documentation for this is hard to find and understand.
I could tell you how to do this for Oracle systems if I'd know the exact version, but there would be a LOT research you'd have to do and I'm not sure if recreating the database wouldn't be less straining on your resources.
A quick google search revealed that shrinking mysql datafiles is not a built in feature for that database system, but there are tools that can do it. The native approach would be to add a datafile of the desired size, move all data there and drop the old ones (and I guess that is what those tools do).
Edit: Using tools like vi or awk on database files usually is a bad idea and will most likely corrupt your database.

Last edited by cero; 02-27-2013 at 04:30 AM..
 

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grass-sqlite(1grass)						Grass User's Manual					      grass-sqlite(1grass)

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grass-sqlite - SQLite driver SQLite driver SQLite driver in GRASS Creating a SQLite database GRASS is automatically creating the SQLite database if it is not yet existing when the first table is created in the SQLite database. It is sufficient to define the connection (see next step). Connecting GRASS to SQLite The database name 'sqlite.db' is at user's choice. Also the file storage location can be freely chosen. If the database does not exist, it will be automatically created when database content is created: # example for storing DB in mapset directory (keep single quotes): db.connect driver=sqlite database='$GISDBASE/$LOCATION_NAME/$MAPSET/sqlite.db' db.connect -p Supported SQL commands All SQL commands supported by SQLite (for limitations, see SQLite help page: SQL As Understood By SQLite and Unsupported SQL). Operators available in conditions All SQL operators supported by SQLite. Browsing table data in DB A convenient SQLite front-end is sqlitebrowser. To open a DB file stored within the current mapset, the following way is suggested (corre- sponds to above database connection): eval `g.gisenv` # use double quotes: sqlitebrowser "$GISDBASE/$LOCATION_NAME/$MAPSET"/sqlite.db SEE ALSO
db.connect, db.execute, db.select SQL support in GRASS GIS SQLite web site, SQLite manual, sqlite - Management Tools Last changed: $Date: 2011-02-07 18:59:50 +0100 (Mon, 07 Feb 2011) $ Help Index GRASS 6.4.2 grass-sqlite(1grass)
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