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Optimistic concurrency control sets few locks on the data in the database, lowering the isolation level that you use in an application. This allows more applications to run concurrently and potentially increases the throughput of the applications. This strategy attempts to obtain locks on the required resources only when the transaction completes.Pessimistic concurrency control implements a higher isolation level by placing locks on the database at the beginning of a transaction. In other words, pessimistic locking assumes there will be a collision in the database and takes precautions to prevent these collisions. A pessimistic locking strategy protects the integrity of the database by guaranteeing, from the beginning of the transaction, that no conflicting transaction can run concurrently.The optimistic concurrency control strategy always allows a transaction to start but cannot guarantee that it will complete. The pessimistic locking strategy cannot guarantee that a transaction will be able to start, but it guarantees that, once started, any transaction can complete.A data warehouse has many fetches, or SELECTs, and few DMLs, or UPDATEs, INSERTs, and DELETEs. An online transaction processing (OLTP) application usually has many DMLs and few SELECTs. Remember that rows selected from a partially complete transaction may not be consistent.Discuss the following points:Identify one benefit and one drawback of each concurrency control strategy in an OLTP application. Explain.Identify one benefit and one drawback of each concurrency control strategy in a data warehouse. Explain.Suggest a scenario for a hypothetical OLTP business system where optimistic concurrency control is most appropriate and another scenario where pessimistic concurrency control is most appropriate.How would the type of user, such as a computer program, an internal business user, or a customer on the web, affect your choices?
A Relational schema of your database in 3NF, clearly indicating attributes, the data type of each attribute, primary and foreign keys, candidate keys, and which attributes are nullable, giving reasons. List any assumptions you need to make.
Name four attributes that you can use to define a data flow in the bus information system. Name four attributes that you can use to define a data store in the bus information system.
To analyse a set of data, and write a memo, identifying and explaining your insights into the operation of Todd Restaurants.
Show all the data in each of the four tables. Do not show foreign key columns. Write names and e-mail addresses for all customers who have had a stove repair that cost more than $50.
our current database uses dictionary-managed tablespaces. In running various performance tuning scripts, you have discovered that one of these tablespaces seems to have run out of space long before you calculated that it would.
You have been requested to give preliminary information on the data requirements for a GIS which is to be used to hold inventory of continental scale vegetation maps for coarse scale land surface
Prepare the relational schema for database
The relations given below keep track of airline flight information:Flights(flno: integer, from: string, to: string, distance:integer, departs: time, arrives: time, price: real)Aircraft(aid: integer, aflame: string, cruisingrange: integer)
Find the average number of books borrowed per member. Take into account that if a member does not borrow any books, then that member does not appear in the borrowed relation at all.
In talking about database security, some aspects to regard as are Data Integrity, Confidentiality, and Malicious Activity. Illustrate how does database security relate to data integrity?
Energy in the home, personal energy use and home energy efficiency and Efficient use of ‘waste' heat and renewable heat sources
Create and run the following sql queries and submit the screen shot of your result. Also submit the file lab_06_03. sql
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