[GRASS-user] increase sqlite performance

[Ivan Marchesini]

Hi guys,

I have a layer with millions of features. I need to join its table with 
another large table based on a common column.

I tried to execute the join but it takes to much to run.

Reading around I understood that, in sqlite, performances can be 
improved altering the "PRAGMA cache_size" which should be helpful if you 
want to use more RAM and less disk i/o.

  (I'm working on a server where I have hundreds of Gb of ram and I 
would like to exploit them)

I tested the following command:

db.execute sql="PRAGMA cache_size = 50000000;"

but then when I run:

db.select sql="PRAGMA cache_size;"

I get

DBMI-SQLite driver error:
Error in sqlite3_step():
database schema has changed

DBMI-SQLite driver error:
Unable to describe table:
database schema has changed

DBMI-SQLite driver error:
Unable to describe table:
database schema has changed

ERROR: SQLite database connection is still busy
dbmi: Protocol error

Any suggestion about what I can do to solve this issue?

Thank you

Ivan