Re: [HACKERS] LZTEXT for rule plan stings

Don Baccus <dhogaza@pacifier.com> writes:
>> What's your basis for asserting the rule is only ~ 1K?

> I looked at the string dumped by pg_dump and it didn't appear to be
> anywhere near 8KB, so I presumed that the actual data stuffed into
> the rule is larger than whatever gets dumped out as the source
> representation.

Yes, the source representation is *vastly* more compact.  A single
result column might look like "tab1.product_id" when dumped by pg_dump,
but the nodetree dump looks more like

      { TARGETENTRY 
      :resdom 
         { RESDOM 
         :resno 1 
         :restype 23 
         :restypmod -1 
         :resname product_id 
         :reskey 0 
         :reskeyop 0 
         :ressortgroupref 0 
         :resjunk false 
         }
       
      :expr 
         { VAR 
         :varno 1 
         :varattno 1 
         :vartype 23 
         :vartypmod -1  
         :varlevelsup 0 
         :varnoold 1 
         :varoattno 1
         }
      }

and (except for not using any excess whitespace) that is exactly what
goes into a rule action string.

As you can see, this is very amenable to compression, especially
when you have a lot of columns in a view.

Someday we might think about using a more compact representation for
stored rules, but there are advantages to using a format that's fairly
easy for a human to examine.

			regards, tom lane