"Sergey Moroz" <smo@mgcp.com> writes:
> I tested performance of my query with limit clause inside plpgsql procedure.
> 2 slightly different situations:
> 1. Sql with limit clause and literal variable (for example 'select field1
> from table1 limit 100')
> 2. The same sql with limit clause and pgplsql variable (for example 'select
> field1 from table1 limit vilimit'). vilimit defined in declare section.
> At first I compared execution plans. they were absolutely equal!
> But in fact first procedure was 10 times!!!! faster then the second!
Exactly what did you do to conclude that the execution plans were the
same? I would not expect the planner to choose the same plan in these
two cases, at least not if 100 is just a small fraction of the total
estimated query output.
regards, tom lane
