Greetings,<br /><br />I was wondering why do we need the Materialize node in the plan below when i explain a query? <br
/><br/><br />1: QUERY PLAN = "Nested Loop (cost=10.99..24.34 rows=1 width=846)" (typeid = 25, len = -1, typmod =
-1,byval = f)<br />----<br />1: QUERY PLAN = " Join Filter: (("inner".cover)::text = ("outer".cover)::text)"
(typeid= 25, len = -1, typmod = -1, byval = f)<br />----<br />1: QUERY PLAN = " -> Index Scan using
idx_cover_ftn_on c_cover_ftn (cost=0.00..9.30 rows=2 width=86)" (typeid = 25, len = -1, typmod = -1, byval = f)<br
/>----<br/>1: QUERY PLAN = " Index Cond: (username = 'user1'::name)" (typeid = 25, len = -1, typmod =
-1,byval = f)<br />----<br />1: QUERY PLAN = " -> Materialize (cost=10.99..11.89 rows=90 width=842)"
(typeid= 25, len = -1, typmod = -1, byval = f)<br />----<br />1: QUERY PLAN = " -> Seq Scan on
books (cost=0.00..10.90 rows=90 width=842)" (typeid = 25, len = -1, typmod = -1, byval = f)<br />----<br /><br /><br
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