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Processes Procedures and code for Database Maintenance?

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Message        tseyfarth          Post subject: Processes Procedures and code 
for Database Maintenance?Posted: Wed Feb 13, 2013 12:24 am                      
   
Joined: Sat Dec 04, 2010 9:14 pm
Posts: 812                Hello all,

Tim H was kind enough to give me a kick off for programatically maintaining a 
database as an application is developed and updated over time.  His idea was to 
use code that during the startup of the application would check its code, 
against the existing database (if any).  This approach seems reasonable but I 
thought I would ask the community at large what their thoughts are.

This would be the very first time I have delved into this kind of challenge.  
Previously I took the wimps way out and simply backed up, and replaced the 
existing db.  This meant new install and set up- lots of wasted time.  And more 
importantly, reportable data was lost, deligated to a backup and a harder 
method to obtain (reports) if necessary!  This time, I would like to solve this 
problem properly and completely from the beginning.

The conceptual challenges I have with the programmatic method (which I do think 
is better than comparing a new db to the old db) are:
1. How does the code *know* that a field length has changed?  Or a Field data 
type has changed?
2. How does the code know that a field name has simply been changed?
3. Field additions appear fairly straightforward. But what about deletions?  
Are they name changes or true deletions?

Once the conceptual understanding is obtained, how to code to compare?  Tim H 
and my ideas were to use the db schema, and compare that to a table list.  

  TableFieldNames = 
array("tamper_events","pms_updates","alarm_events","door_close_events","door_open_events","exit_attempts",
"entry_attempts",_  "last_updated_date_time", "rowid",  "datex", 
"invalid_code", "other_access_attempts")
  

But then what would be the best method to track the field *data type*?  One 
idea I had was to compare the data type for the matching field Property - but 
how to programatically know the data type of a particular Property?

Does anyone have any idea, suggestions or code samples/snippets they would like 
to share?  I did check the RSDS Code Library, but did not see anything that 
would do this.

Also, initial targeted DB Is SQLite, but PostgreSQL will be necessary as well 
not long after this implementation.

Thanks again all!
Tim   
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