An LRU algorithm helps a program work with the computer's cache. What does LRU stand for?

An LRU algorithm helps a program work with the computer's cache. What does LRU stand for?

• Least recently usable
• Last received unit
• Least recently used
• Lost recovered unit 

EXPLANATION

LRU (Least Recently Used) Page replacement algorithm.

cache algorithms are optimizing instructionsor algorithmsthat a computer program or a hardware-maintained structure can follow in order to manage a cache of information stored on the computer. When the cache is full, the algorithm must choose which items to discard to make room for the new ones.

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What is the correct water temperature range to brew coffee at?

What is the correct water temperature range to brew coffee at?

• 175-185 (F) / 80-85 (C)
• 195-205 (F) / 90-96 (C)
• 208-212 (F) / 98-100 (C)
• 350-400 (F) / 175-205 (C)

EXPLANATION

The ideal temperature range for hot brewing is 195 to 205 degrees Fahrenheit. This is hot enough to extract carefully and quickly, but not so hot that it’s uncontrollable.

• Coffee over 205 degrees Fahrenheit tends to over extract things from the grounds very easily, producing bitter coffee.
• Water under 195 degrees has a difficult time extracting, which often leads to sour, underdeveloped coffee.

The 195 to 205 degree range isn’t the objective gold standard for water temperature for coffee brewing. It’s just the range that most people around the world tend to use the most because it tends to make the best, most balanced coffee. You are free to depart from this proven temperature range, but I don’t suggest it unless you’re a seasoned coffee veteran.
There are quite a few coffee professionals who use lower temperatures to achieve different results in their coffee. One World Aeropress Championship finalist in 2013 used water at 176 degrees. Another major figure in the coffee world commonly uses 190 degrees in his Aeropress recipe.
It can be done if you have master-level control of other coffee variables, but most of us like to stick to the tried and true, classic range of 195 to 205 degrees.

 

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If you experience a system failure, what’s the best way to recover your database?

If you experience a system failure, what’s the best way to recover your database?

• Rollback
• Switch to duplicate database
• Rollforward
• Reprocess transactions 

EXPLANATION

 1.

Recovery is needed when a database instance that has failed is restarted or a surviving database instance takes over a failed one. In roll-backward recovery, the active transactions at the time of failure are aborted and the resourced allocated for those transactions are released. In roll-forward recovery, the updates recorded in the redo log are transferred to the database so that they are not lost.

2.

Recovery is needed when a database instance that has failed is restarted or a surviving database instance takes over a failed one. In roll-backward recovery, the active transactions at the time of failure are aborted and the resourced allocated for those transactions are released. In roll-forward recovery, the updates recorded in the redo log are transferred to the database so that they are not lost.

3.

Recovery is needed when a database instance that has failed is restarted or a surviving database instance takes over a failed one. In roll-backward recovery, the active transactions at the time of failure are aborted and the resourced allocated for those transactions are released. In roll-forward recovery, the updates recorded in the redo log are transferred to the database so that they are not lost. 

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Which of the following is true about open source DBMS?

Which of the following is true about open source DBMS?

• Free software with proprietary source code
• Competitive with PC packages and not SQL compliant
• Not competitive with PC packages and SQL compliant
• Free software with publicly available source code 

EXPLANATION

Which of the following is true concerning open-source DBMS?

A. Is free or nearly free database software whose source code is publicly available
B. Is free or nearly free database software whose source code is not publicly available
C. Is not competitive against PC-oriented packages and is fully SQL compliant
D. Is competitive against PC-oriented packages and is not fully SQL compliant
Answer: Option A

 SOURCE

https://www.examveda.com/which-of-the-following-is-true-concerning-open-source-dbms-24525/

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What is backward database recovery?

What is backward database recovery?

• Where after-images are applied to the database
• Switching to an existing copy of the database
• Where after-images and before-images are applied
• Where before-images are applied to the database 

EXPLANATION

 Backward Recovery. Backward recovery restores a journaled database to a prior state. Backward processing starts by rolling back updates to a checkpoint (specified by -SINCE or -AFTER) prior to the desired state and replaying database updates forward till the desired state.

Backward Recovery uses "BEFORE_IMAGE" journaling. With BEFORE_IMAGE journaling, GT.M captures the database updates, as well as "snapshots" of portions of the database immediately prior to the change caused by the update. Unlike forward recovery which works on a backup database, backward recovery works only on  production (current) database provided it is usable and BEFORE_IMAGE journaling is enabled.

 

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