From 45b559be28325dad5f7d97572721e362bae9b952 Mon Sep 17 00:00:00 2001 From: LtWorf Date: Wed, 1 Apr 2009 13:37:56 +0000 Subject: [PATCH] completed complexity of unary functions git-svn-id: http://galileo.dmi.unict.it/svn/relational/trunk@118 014f5005-505e-4b48-8d0a-63407b615a7c --- complexity | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/complexity b/complexity index 48fadab..e3025a8 100644 --- a/complexity +++ b/complexity @@ -64,5 +64,11 @@ Notation 1.3 Projection + The projection operation creates a copy of the original relation + using only a subset of its fields. Time for the copy is something + like O(|n|*f) where f is the number of fields to copy. + But that's not all. Since relations are set, duplicated items are not + allowed. So after extracting the wanted elements, it has to check if + the new tuple was already added to the new relation. And this brings + the complexity to O((|n|*f)²). -xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx \ No newline at end of file