Which four factors can influence the rate of SQL apply on a logical standby database?
A.
the size of the undo tablespace on the logical standby database
B.
the number of full table scans performed by SQL apply
C.
the number of coordinator processes on the standby database instance
D.
the size of the shared pool
E.
the number of APPLIER processes
F.
the number of PRE PARER processes
Hi
If we consider the figure 11-1 here http://docs.oracle.com/database/121/SBYDB/manage_ls.htm#SBYDB4804
I will say that correct answers are
C,D,E,F
regards
B, D, E, F
Correct
B:
One of the primary causes for long-running transactions in a SQL Apply environment is because of Full Table Scans.
Reference:
https://docs.oracle.com/database/121/SBYDB/troubleshooting.htm#SBYDB4929
D:
The LCRs are staged in the shared pool of the system global area (SGA), known as the LCR cache.
Reference:
https://docs.oracle.com/cd/B19306_01/server.102/b14239/manage_ls.htm#g1057004
E:
http://docs.oracle.com/database/121/SBYDB/manage_ls.htm#SBYDB4805
F:
Multiple PREPARER processes can be active for a given redo log file.
Reference:
http://docs.oracle.com/database/121/SBYDB/manage_ls.htm#SBYDB4805
Incorrect:
C:
There can be only one coordinator
B, D, E, F
– On the primary database, if a table does not have a primary key or a unique index and you are certain the rows are unique, then create a primary key RELY constraint. On the logical standby database, create an index on the columns that make up the primary key. By creating an index on the following tables, performance can be improved significantly.
– Adjusting the number of APPLIER processes will help you achieve greater throughput In rare cases do you need to adjust the number of PREPARER processes. Before you decide to increase the number of PREPARER processes.
– Adjust memory used by Logical Change Record (LCR) cache by increasing SGA. LCR cache is a structure in SGA, a portion of the shared pool size.
– Statistics should be gathered on the standby database because the cost-based optimizer (CBO) uses them to determine the optimal query execution path. New statistics should be gathered after the data or structure of a schema object is modified in ways that make the previous statistics inaccurate.
– By default transactions are applied on the logical standby database in the exact order in which they were committed on the primary database. However, many applications do not require such strict ordering among all transactions. Adjusting strict ordering typically results in higher apply rates at the logical standby database.
https://docs.oracle.com/database/121/SBYDB/manage_ls.htm#SBYDB4839