From /src/include/utils/tuplestore.h
"The materialize shields the sort from the need to do mark/restore and thereby allows it to perform its final merge pass on-the-fly; while the materialize itself is normally cheap since it won't spill to disk unless the number of tuples with equal key values exceeds work_mem" -- Shoaib Mir EnterpriseDB (www.enterprisedb.com) On 6/11/07, rupesh bajaj <[EMAIL PROTECTED]> wrote:
Hi, What is the meaning of 'materializing' a relation after sequential scan? explain select * from tb1, tb2 where tb1.c1 = tb2.c2; QUERY PLAN ---------------------------------------------------------------- Nested Loop (cost=1.03..2.34 rows=3 width=24) Join Filter: (tb1.c1 = tb2.c1) -> Seq Scan on tb2 (cost=0.00..1.04 rows=4 width=12) -> Materialize (cost=1.03..1.06 rows=3 width=12) -> Seq Scan on tb1 (cost= 0.00..1.03 rows=3 width=12) In this above plan, what does 'Material' mean? Thanks, Rupesh