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  2. Database index - Wikipedia

    en.wikipedia.org/wiki/Database_index

    The non-clustered index tree contains the index keys in sorted order, with the leaf level of the index containing the pointer to the record (page and the row number in the data page in page-organized engines; row offset in file-organized engines). In a non-clustered index, The physical order of the rows is not the same as the index order.

  3. Full table scan - Wikipedia

    en.wikipedia.org/wiki/Full_table_scan

    Full table scan occurs when there is no index or index is not being used by SQL. And the result of full scan table is usually slower that index table scan. The situation is that: the larger the table, the slower of the data returns. Unnecessary full-table scan will lead to a huge amount of unnecessary I/O with a process burden on the entire ...

  4. Determining the number of clusters in a data set - Wikipedia

    en.wikipedia.org/wiki/Determining_the_number_of...

    The average silhouette of the data is another useful criterion for assessing the natural number of clusters. The silhouette of a data instance is a measure of how closely it is matched to data within its cluster and how loosely it is matched to data of the neighboring cluster, i.e., the cluster whose average distance from the datum is lowest. [8]

  5. DBSCAN - Wikipedia

    en.wikipedia.org/wiki/DBSCAN

    Points B and C are not core points, but are reachable from A (via other core points) and thus belong to the cluster as well. Point N is a noise point that is neither a core point nor directly-reachable. Reachability is not a symmetric relation: by definition, only core points can reach non-core points.

  6. Extensible Storage Engine - Wikipedia

    en.wikipedia.org/wiki/Extensible_Storage_Engine

    Indexes are defined to persist interesting orders of data, and allow both sequential access to records in index order, and direct access to records by index column values. Clustered indexes in ESE must also be primary, meaning that the index key must be unique. Clustered and non-clustered indexes are represented using B+ trees. If an insert or ...

  7. Billionaire entrepreneur and top adviser to President-elect Donald Trump, Elon Musk, touted that he has reaped the benefits of a controversial class of weight-loss drugs, after fellow top Trump ...

  8. Cluster analysis - Wikipedia

    en.wikipedia.org/wiki/Cluster_analysis

    Cluster analysis or clustering is the task of grouping a set of objects in such a way that objects in the same group (called a cluster) are more similar (in some specific sense defined by the analyst) to each other than to those in other groups (clusters).

  9. B-tree - Wikipedia

    en.wikipedia.org/wiki/B-tree

    According to Knuth's definition, a B-tree of order m is a tree which satisfies the following properties: [7] Every node has at most m children. Every node, except for the root and the leaves, has at least ⌈m/2⌉ children. The root node has at least two children unless it is a leaf. All leaves appear on the same level.