[Bucardo-general] Patch to Enable Filtering in bucardo_add_delta functions

[Ben Allen]

I never got any input on this patch from anyone. Is this useful to  
anyone else, or should I just keep these changes local?

Thanks,

Ben

On Mar 12, 2009, at 3:47 PM, Benjamin Allen wrote:

> Hello Everyone,
>
> To solve the problem Meg and I were having with being able to filter  
> out data from a table (goat) from being synced I've added a  
> goatfilter table to the bucardo database and modified the  
> validate_sync function. The table has an id, status, FK to the goat  
> table, and a src_code column. The src_code column is used to store  
> the source code of the bucardo_add_delta function for whichever goat  
> you're working with. Our example is attached, so the goatfilter  
> table would be populated like so:
>
> INSERT INTO goatfilter VALUES ( DEFAULT, 12, $$
> SOURCE_CODE GOES HERE
> $$ );
>
> Where 12 is the goat.id of the goat you're working with.
>
> Limitations as of right now:
>
> - The src_code of goatfilter totally replaces the default function  
> source code if it exists. This is a bit clunky as you have to store  
> the entire function in the src_code column.
> 	- Maybe instead of writing out the entire function, we could insert  
> just a chunk of code into the already existing code. If you look at  
> the example function you can see we only added code at the beginning  
> of the function.
>
> - Even though the data we want filtered is not added to the  
> bucardo_delta table the sync is still kicked when filtered data is  
> touched in the database.
> 	- Fixing this would involve doing filtering in the  
> bucardo_triggerkick function.
>
> - Current modifications to the validate_sync method takes just the  
> first row from the select statement on the goatfilter table for a  
> given goat.id. There's no validation that only one entry is created  
> in the goatfilter table per goat.
>
> I'm wondering if anyone can think up a better way or place of doing  
> filtering of data. I've explored using PostgreSQL Views and Bucardo  
> customcode and found no real logical way of doing it. By filtering  
> it at the bucardo_add_delta function its eliminating any additional  
> network traffic and processing from Bucardo. Thoughts?
>
> Regards,
>
> Ben Allen
>
>
>
> <bucardo_filter.patch><bucardo_add_delta_custom.sql>
>
>
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