Tag: databases

To answer this question, we need to understand the concept of RAID (Redundant Array of Independent Disks) and data protection levels associated with it.

RAID is a technology that combines multiple physical disk drives into a single logical unit to improve performance, reliability, and data protection. Different RAID levels provide different levels of data protection, depending on the redundancy and fault tolerance mechanisms they employ.

Now, let's go through each option to understand why it is correct or incorrect:

Option A) RAID 1 and Fallback - This option is correct because RAID 1, also known as mirroring, provides the highest level of data protection. In RAID 1, data is mirrored across multiple drives, meaning that each drive contains an exact copy of the data. This redundancy ensures that even if one drive fails, the data can still be accessed from the other drive. Fallback refers to the ability to switch to a backup or redundant system in case of failure, further enhancing data protection.

Option B) RAID 5 and Fallback - This option is incorrect because RAID 5 does not provide the maximum level of data protection. RAID 5 uses striping with parity, distributing data and parity across multiple drives. While it offers some fault tolerance by allowing the system to continue functioning even if one drive fails, it does not provide the same level of redundancy as RAID 1.

Option C) RAID 5 and No Fallback - This option is incorrect for the same reasons mentioned above. RAID 5 without fallback does not provide the maximum level of data protection.

Option D) RAID 1 and No Fallback - This option is incorrect because while RAID 1 offers a high level of data protection, not having fallback limits the ability to switch to a backup or redundant system in case of failure, reducing the overall level of data protection.

Therefore, the correct answer is A) RAID 1 and Fallback. This option provides the maximum level of data protection by combining the redundancy of RAID 1 with the ability to switch to a backup or redundant system in case of failure.

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• Wrong explanation

To answer this question, we need to understand the concept of NUPIs (Non-Unique Primary Index) and how they are used for data distribution in a database.

Option A) The statement "The increase of hash buckets has resulted in more hash collisions" is incorrect. Increasing the number of hash buckets reduces the likelihood of hash collisions, as it provides more space for the data to be distributed evenly.

Option B) The statement "Duplicate NUPI values will produce the same row hash" is correct. In a database using NUPIs, rows with duplicate NUPI values will be hashed to the same hash bucket. This ensures that rows with the same NUPI value are stored together for efficient access.

Option C) The statement "Uniform row distribution is accomplished using UPIs" is incorrect. UPIs (Unique Primary Index) are used for unique row identification, not for achieving uniform row distribution. NUPIs are typically used for data distribution across multiple AMPs (Access Module Processors) in the Teradata database.

Option D) The statement "The low-order 16 bits of the row hash are input to the hash map" is not directly related to NUPIs or data distribution. It seems to be discussing a specific implementation detail that is not relevant to the given question.

Based on the explanations above, the correct answer is Option B. Duplicate NUPI values will produce the same row hash, ensuring that rows with the same NUPI value are stored together for efficient access.

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• Wrong explanation

To answer this question, we need to understand the Sybase database and its equivalent functions.

The Sybase equivalent function for the SQL char_length is len.

Let's go through each option to understand why it is correct or incorrect:

Option A) length - This option is incorrect because length is not the Sybase equivalent function for char_length.

Option B) char_length - This option is incorrect because char_length is not the Sybase equivalent function for char_length.

Option C) char_len - This option is incorrect because char_len is not the Sybase equivalent function for char_length.

Option D) len - This option is correct because len is the Sybase equivalent function for char_length.

The correct answer is Option D. This option is correct because len is the Sybase equivalent function for char_length.

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• Wrong explanation