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Ans. synchronized is a keyword and a modifier. The synchronized keyword is used to indicate that a method can be accessed exclusively by one thread at a time.
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Ans. Source connectors are the connectors that are used to get information from the source whereas sink connectors are used to deploy information to the destination.
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Ans. Yes, it's a project by confluent that provides in built mechanism for streaming records from bigdata data source to apache kafka message queues and vice versa. It provides a variety of source and sink connectors to achieve this.
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Ans. Counter controlled repetitions are the loops that are controlled with the use of counters or the loops where the number of repetitions are known in advance. for loop in java is the counter controlled repetition.
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Ans. This looks like the case for optimistic locking wherein hibernate suspects that the information in table was updated by some other transaction after the entity was loaded by current transaction.
One way is to have synchronized entity state and don't detach the entity. Other could be to merge the entity with the table record rather than just directly persisting the entity.
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Ans. It's the way for synchronization wherein we can store version information in the table , so that if the same entity is updated by two transactions, the last to commit changes is informed of the conflict, and does not override the other transaction's work.
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Ans. Performance of a system doesn't solely rely on size of processor or it's communication size. It should also be compatible with other resources like memory, storage etc. Moreover it makes no sense to have 64 bit systems when there is hardly any software than can run on 64 bit system.
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Ans. Garbage collection mechanism frees up the memory that is no longer needed. In languages like C / C++ the deallocation needs to be done explicitly by the programmer and hence any leniency may result in memory leak. Garbage collection in java ensures that all unused memory is reclaimed and hence there are no memory leaks.Moreover it relieves the programmer from the hassle of carefully releasing all memory.
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Ans. Primary Key constraint means that the column(s) should be unique and doesn't allow null. So Primary key constraint implies unique and not null constraint too.
Unique constraint implies not null constraint too as allowing null would violate uniqueness on those columns.
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Ans. Unique constraint ensures that a columns or combination or columns are always unique in a table and hence doesn't allow null or duplicates to be entered for the column or combination of columns.
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Ans. Application is unable to insert a record as it violates a unique constraint.
The exception states the constraint and Table can be located by the Entity mapping. So I will go to the DB and will first check to which all columns the unique constraint applies. And then I will go and check the code and logs to see how come the duplicate column values were attempted to be inserted when they were not supposed to be.
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Null value means that the value is yet to be assigned or need not be assigned whereas empty value means that the blank value has already been assigned once. Null is the default for the null able columns that hasn't be assigned any value.
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Ans. Though it's useful but it's not as useful as overriding member or object methods. We cannot achieve polymorphic behavior with static methods by overriding their definition in derived class.
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We need methods to access variables in a polymorphic way as overriding only happens with methods and not with variables. Moreover getter provides a way to minimally open the access window for the object and hence provides better encapsulation. To add to those, we can have validation in the getter method before returning elements.
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Which of the following Design pattern has been used with Hibernate Criteria ?
