Slow Materialized View Refresh After Upgrading Materialized View database To 19C
(Doc ID 2766301.1)
Last updated on APRIL 05, 2021
Applies to:Oracle Database - Enterprise Edition - Version 188.8.131.52.0 and later
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You are having issues while refreshing some materialized views on the database after its upgrade from 184.108.40.206 to 19C. There is one materialized view refresh session which is waiting for "db file sequential read" while executing an insert on the materialized view itself, on the remote site(materialized view log) you see the corresponding session with ACTIVE status waiting for "SQL*Net more data to client".
The refresh process is taking too much time and enabling trace 10046 level12 on the session refreshing the mview you see lots of messages like these:
WAIT #140055101335816: nam='db file sequential read' ela= 690 file#=1072 block#=2604108 blocks=1 obj#=151287 tim=320107026011
WAIT #140055101335816: nam='db file sequential read' ela= 215 file#=1071 block#=2603916 blocks=1 obj#=151287 tim=320107026343
WAIT #140055101335816: nam='db file sequential read' ela= 173 file#=1071 block#=2603980 blocks=1 obj#=151287 tim=320107026570
WAIT #140055101335816: nam='db file sequential read' ela= 154 file#=1070 block#=2603532 blocks=1 obj#=151287 tim=320107026772
WAIT #140055101335816: nam='db file sequential read' ela= 150 file#=1070 block#=2603596 blocks=1 obj#=151287 tim=320107026968
OBJ#151287 is the materialized view object, so basically, the session is waiting on a "db file sequential read" during an insert operation on the table itself.
The materialized view site upgraded from 11204 to 19C
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