28. Goal
Collect
sta.s.cs
that
are
"good
enough"
to
meet
most
needs
most
of
the
.me.
29. Say
you
were
standing
with
one
foot
in
the
oven
and
one
foot
in
an
ice
bucket.
According
to
the
percentage
people,
you
would
be
perfectly
comfortable.
–
Bobby
Bragan
58. SPJ
–
Simple
View
Merging
is transformed into
Merged automatically as it is deemed “always better” for the optimizer to work with direct joins. 58
59. Complex
View
Merging
is transformed into
“Complex” due to GROUP BY. CVM can also be done when using DISTINCT or outer join. 59
60. Filter
Push-‐Down
is transformed into
Purpose: To push outer query predicates into view to perform earlier filtering. 60
61. Predicate
Move-‐Around
is transformed into
Purpose: To move inexpensive predicates into view query blocks to perform earlier filtering. 61
Can generate filter predicates based on transitivity or functional dependencies.
62. Join
Factoriza.on
is transformed into
Combines branches of UNION / UNION ALL that join a common table in order to reduce # of accesses to that table.
62