Practice Question - Clustered Indexing
Duration: 2 min
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This educational video features a lecture by Sanchit Jain from KnowledgeGate, focusing on a specific multiple-choice question from the GATE 2013 examination regarding database management systems. The slide displays the question: 'An index is clustered, if'. Four options are presented: (a) it is on a set of fields that form a candidate key, (b) it is on a set of fields that include the primary key, (c) the data records of the file are organized in the same order as the data entries of the index, and (d) the data records of the file are organized not in the same order as the data entries of the index. The instructor systematically evaluates these options to define a clustered index.
Chapters
0:00 – 1:32 00:00-01:32
The video begins with the full question text visible on the screen. The instructor reads the question and the four options aloud. He explains that options (a) and (b) are incorrect because a clustered index is not defined merely by being on a candidate or primary key, although it often is. He then focuses on the physical organization of data. He states that a clustered index implies the physical order of the data records matches the order of the index entries. Consequently, he underlines option (c) on the screen, identifying it as the correct definition. He contrasts this with option (d), which describes a non-clustered index where the physical order does not match the index order. The video concludes with the instructor confirming that option (c) is the right answer for the GATE 2013 question.
The lecture effectively clarifies the technical definition of a clustered index by contrasting it with other index types. The core concept taught is that a clustered index physically sorts the data file on the disk to match the index structure, which is a crucial distinction for database performance and storage optimization. This specific GATE question serves as a practical application of that theoretical definition.