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Oracle Tips by Burleson |
Materialized View Parameters
This set of parameters controls the behavior
and refresh mechanisms of materialized views.
* _query_rewrite_fudge - This parameter
controls the cost based query rewrite with MVs fudge factor
* _mav_refresh_consistent_read – To avoid undo
log issues, you can set this parameter to FALSE and refresh
materialized views using an inconsistent read snapshot
Materialized View
List of undocumented Oracle parameters
Parameter
Current Instance
Name
Value Value
---------------------------------------- ----------
--------------------
Parameter
Description
------------------------------------------------------------------------------_explain_rewrite_mode
FALSE FALSE
allow additional messages to be generated during explain rewrite
_mav_refresh_consistent_read
TRUE TRUE
refresh materialized views using consistent read snapshot
_mav_refresh_double_count_prevented
FALSE FALSE
materialized view MAV refreshes avoid double counting
_mav_refresh_opt
0 0
optimizations during refresh of materialized views
_mav_refresh_unionall_tables
3 3
# tables for union all expansion during materialized view refres
_mv_refresh_delta_fraction
10 10
delta mv as fractional percentage of size of mv
_mv_refresh_eut
TRUE TRUE
refresh materialized views using EUT(partition)-based algorithm
_mv_refresh_new_setup_disabled
FALSE FALSE
materialized view MV refresh new setup disabling
_mv_refresh_selections
TRUE TRUE
create materialized views with selections and fast refresh
_mv_refresh_use_stats
TRUE TRUE
pass cardinality hints to refresh queries
_pre_rewrite_push_pred
FALSE FALSE
push predicates into views before rewrite
_query_cost_rewrite
TRUE TRUE
perform the cost based rewrite with materialized views
_query_rewrite_1
TRUE TRUE
perform query rewrite before&after or only before view merging
_query_rewrite_2 TRUE
TRUE
perform query rewrite before&after or only after view merging
_query_rewrite_drj
TRUE TRUE
mv rewrite and drop redundant joins
_query_rewrite_expression
TRUE TRUE
rewrite with cannonical form for expressions
_query_rewrite_fpc
TRUE TRUE
mv rewrite fresh partition containment
_query_rewrite_fudge
90 90
cost based query rewrite with MVs fudge factor
_query_rewrite_jgmigrate
TRUE TRUE
mv rewrite with jg migration
_query_rewrite_or_error
FALSE FALSE
allow query rewrite, if referenced tables are not dataless
_query_rewrite_vop_cleanup
TRUE TRUE
prune frocol chain before rewrite after view-merging
_subquery_pruning_mv_enabled
FALSE FALSE
enable the use of subquery predicates with MVs to perform pruning
For more details, see the "Easy
Oracle Series" a set of books especially designed by Oracle
experts to get you started fast with Oracle database technology.
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