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Listener refused the connection due to NetExcepti​on

I was testing some piece of code for calculation of new date on the basis of a given pattern and the specified date. I wrote a method to automate the test cases to generates those patterns and calculate the new date for each date of the specified date of the range of years. Since there were around 1 million pattern test cases are possible, so I want to insert this data in database for any future reference. After creating a pattern I was inserting data of the pattern and the calculation date along with the calculated date. It was working fine. I was prepare to hit the start button now, after testing different patterns individually. I hit the run button and it started its executions, but in the middle, I got this error. java.sql.SQLException: Listener refused the connection with the following error:ORA-12516, TNS:listener could not find available handler with matching protocol stack       at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:4...
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B*Tree Reverse index

B*Tree Reverse index is one of the index types that is supported by oracle. It more or less behaves like b*tree unique & non-unique index but only difference is the way it constructs the tree. In this index, index value is stored in the reverse direction when compared to the values in the actual data table. This index is used in order to distribute the index data evenly across all the leaf index nodes if table data is skewed very high. Like b*tree index, this index doesn’t understand NULL. This B*Tree Reverse index can be created on a single column or more than one column. More than one B*Tree Reverse index can be created for the same data table. HOW TO VERIFY: How to verify whether the created index is reverse index or not? Fire this query, select index_type from user_indexes where index_name = 'DEPT_ID_INDX' ð   This query would return “ NORMAL/REV ” (it means it is B*Tree index but of “Reverse” type) LITTLE-KNOWN FACTS TO BE REMEMBERED: ·      ...
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B*TREE non-unique index

In continuation with the last chapter , B*Tree with unique index, here are some thoughts on B*Tree with non unique index. DEFINITION: B*TREE non-unique index is one of the index types that is supported by oracle. If this index is imposed on a column, then all the non-null values don’t need to be unique. It means this index allows NULL value to be stored in the column of the table and all the non-NULL values can be same as well as different too. But all the index values in the index table would be unique. This is achieved by grouping all the ROWIDs of a single index value in a single index record. It means if 3 table records are there for a single value in a column on which this non-unique index is created, then in the index table, you will find only one index record but all these 3 ROWIDS would be mapped. This non-unique index can be created on a single column or more than one column. More than one non-unique index can be created for the same data table. HOW TO VERIFY: How to verif...
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