Oracle updating through view

Posted by / 04-Jan-2018 14:29

A value greater than 80-90% is good, less could indicate problems. It can be reduced by setting the storage parameters on the table to appropriate values. If it is specified, the error is ignored and the tables data will be inserted. The packages used by DBAs may include: DBMS_SHARED_POOL, DBMS_UTILITY, DBMS_SQL, DBMS_DDL, DBMS_SESSION, DBMS_OUTPUT and DBMS_SNAPSHOT. How many should be used If the UNIX system being used is capable of asynchronous IO then only one is required, if the system is not capable of asynchronous IO then up to twice the number of disks used by Oracle number of DB writers should be specified by use of the db_writers initialization parameter. You are using hot backup without being in archivelog mode, can you recover in the event of a failure? One is to look at the v$session or v$process views.If you simply take the ratio of existing parameters this will be a cumulative value since the database started. How do you correct it Row chaining occurs when a VARCHAR2 value is updated and the length of the new value is longer than the old value and won? It can be corrected by export and import of the effected table. Give one method for transferring a table from one schema to another: There are several possible methods, export-import, CREATE TABLE... Another way is to check the current_logins parameter in the v$sysstat view.As objects grow they take chunks of additional storage that are composed of contiguous data blocks.

If not specified in this order will result in the final return being done twice because of the way the %NOTFOUND is handled by PL/SQL. What are SQLCODE and SQLERRM and why are they important for PL/SQL developers? Another indication is steadily decreasing performance with all other tuning parameters the same. What is the general guideline for sizing db_block_size and db_multi_block_read for an application that does many full table scans? The two should have a product equal to 64 or a multiple of 64. What is the fastest query method for a table Fetch by rowid 7. What initialization parameter should be turned on to get full TKPROF output?The benefit of taking a hot backup is that the database is still available for use while the backup is occurring and you can recover the database to any point in time.The benefit of taking a cold backup is that it is typically easier to administer the backup and recovery process.They can be used in exception handling to report, or, store in an error log table, the error that occurred in the code. Another possible method is to just use the SHOW ERROR command, but this only shows errors. Once the trace file is generated you run the tkprof tool against the trace file and then look at the output from the tkprof tool. The major sort are parameter is the SORT_AREA_SIZe parameter. You can increase copy latches via the initialization parameter LOG_SIMULTANEOUS_COPIES to twice the number of CPUs on your system. Where can you get a list of all initialization parameters for your instance? This is bad since it makes tracking which table the constraint belongs to or what the constraint does harder. What happens if a tablespace clause is left off of a primary key constraint clause This results in the index that is automatically generated being placed in then users default tablespace. This can be prevented or mitigated by breaking the transaction into a set of smaller transactions or increasing the size of the rollback segments and their extents. How can you tell if a database object is invalid By checking the status column of the DBA_, ALL_ or USER_OBJECTS views, depending upon whether you own or only have permission on the view or are using a DBA account. A user is getting an ORA-00942 error yet you know you have granted them permission on the table, what else should you check You need to check that the user has specified the full name of the object (select empid from scott.emp; instead of select empid from emp;) or has a synonym that balls to the object (create synonym emp for scott.emp;) 14.These are especially useful for the WHEN OTHERS exception. How can you find within a PL/SQL block, if a cursor is open? The DBMS_OUTPUT package can be used to show intermediate results from loops and the status of variables as the procedure is executed. This can also be used to generate explain plan output. When looking at v$sysstat you see that sorts (disk) is high. How about an indication if they are default settings or have been changed You can look in the file for an indication of manually set parameters. Since this will usually be the same tablespace as the table is being created in, this can cause serious performance problems. What is the proper method for disabling and re-enabling a primary key constraint You use the ALTER TABLE command for both. A developer is trying to create a view and the database won? He has the "DEVELOPER" role which has the "CREATE VIEW" system privilege and SELECT grants on the tables he is using, what is the problem You need to verify the developer has direct grants on all tables used in the view. t create a stored object with grants given through views. If you have an example table, what is the best way to get sizing data for the production table implementation The best way is to analyze the table and then use the data provided in the DBA_TABLES view to get the average row length and other pertinent data for the calculation.

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Use of double ampersands tells SQLPLUS to resubstitute the value for each subsequent use of the variable, a single ampersand will cause a reprompt for the value unless an ACCEPT statement is used to get the value from the user. You want to include a carriage return/linefeed in your output from a SQL script, how can you do this The best method is to use the CHR() function (CHR(10) is a return/linefeed) and the concatenation function "||". CASCADE;) and that you need to concatenate using the ? If you use a min/max function against your rowid and then select against the proposed primary key you can squeeze out the rowids of the duplicate rows pretty quick.