A table of contents is the titles of books or chapters arranged for reference. Most of the chapter titles listed in the book catalogue and books and periodicals are placed before the text.
The role of indexes and directories
Index refers to a special data structure, which consists of an index key and a record pointer or record number pointing to the corresponding record in the data file. An index key is a recorded data item or a set of data items. Index is used to improve the efficiency of data query, but it also introduces storage cost and update cost.
In a relational database, an index is an independent physical storage structure that sorts the values of one or more columns in a database table. It is a collection of values in one or more columns in a table and a corresponding list of logical pointers to data pages that physically identify these values in the table. The function of the index is equivalent to the catalogue of books, and you can quickly find what you need according to the page numbers in the catalogue.
The contents of the book will help us understand what the book is about, and most of them will also reflect the framework structure and theme to guide our next reading.