[SQL-CVS] [ sqlobject-Patches-1539325 ] fromDatabase and delColumn for sqlite

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Patches item #1539325, was opened at 2006-08-12 14:42
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Category: None
Group: None
Status: Open
Resolution: None
Priority: 5
Submitted By: Arlo Belshee (abelcodemonk)
Assigned to: Nobody/Anonymous (nobody)
Summary: fromDatabase and delColumn for sqlite

Initial Comment:
This patch implements both fromDatabase and delColumn 
for sqlite. I added sqlite to the appropriate 
existing tests; it passes them.

fromDatabase is done by parsing the table creation 
sql from the sqlite_master table. This will work with 
any sqlite 3, and I think dates back into sqlite 2, 
but I'm not sure.

delColumn is implemented by renaming the table, 
creating a new table without the one column, then 
copying all the data over. This is obviously not as 
efficient as on DBs that support drop column 
directly, but it works.

This implementation of dropColumn does deal correctly 
with triggers, foreign keys, and indices that 
reference the table whose column is being dropped. It 
does not deal correctly with triggers & indices 
attached directly to the table being altered. 
Attached items will be lost. Extending the 
implementation to support re-creating those indices & 
triggers should be straightforward, but is beyond my 
needs. You are welcome to do so.

Finally, this patch slightly improves the 
implementation of addColumn for sqlite. It performs a 
vacuum operation after each column add. See the 
sqlite documentation for why this is a good idea.


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