Amit Kapila wrote:

> I think it is because heap_getattr() is not that cheap.  We have
> noticed the similar problem during development of scan key push down
> work [1].

One possibility to reduce the cost of that is to use whole tuple deform
instead of repeated individual heap_getattr() calls.  Since we don't
actually need *all* attrs, we can create a version of heap_deform_tuple
that takes an attribute number as argument and decodes up to that point.

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services


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