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  2. Lookup table - Wikipedia

    en.wikipedia.org/wiki/Lookup_table

    In computer science, a lookup table (LUT) is an array that replaces runtime computation with a simpler array indexing operation, in a process termed as direct addressing.The savings in processing time can be significant, because retrieving a value from memory is often faster than carrying out an "expensive" computation or input/output operation. [1]

  3. Database index - Wikipedia

    en.wikipedia.org/wiki/Database_index

    An index is a copy of selected columns of data, from a table, that is designed to enable very efficient search. An index normally includes a "key" or direct link to the original row of data from which it was copied, to allow the complete row to be retrieved efficiently.

  4. Help:Basic table markup - Wikipedia

    en.wikipedia.org/wiki/Help:Basic_table_markup

    |-adds a new row, which should be followed by the same number of cells found in other rows. Note, rowspan="2" and colspan="2" can be used on cells to span multiple rows and columns. Header cells are created with ! Header cell, which can be column or row headers. Data cells are created with | Data cell. A new column can be added by adding ...

  5. Help:Creating tables - Wikipedia

    en.wikipedia.org/wiki/Help:Creating_tables

    Change "m" to the number of the column minus 1. 2nd column from the left would be "1". 3rd column from the left would be "2". The row number column created by Template:Static row numbers is not counted in these calculations. Fill in the "replace with" box with: $1[[$3]]$4. Then click "Replace all".

  6. Reverse index - Wikipedia

    en.wikipedia.org/wiki/Reverse_index

    In database management systems, a reverse key index strategy reverses the key value before entering it in the index. [1] E.g., the value 24538 becomes 83542 in the index. Reversing the key value is particularly useful for indexing data such as sequence numbers , where each new key value is greater than the prior value, i.e., values ...

  7. MultiValue database - Wikipedia

    en.wikipedia.org/wiki/MultiValue_database

    In a MultiValue database system: a database or schema is called an "account" a table or collection is called a "file" a column or field is called a field or an "attribute", which is composed of "multi-value attributes" and "sub-value attributes" to store multiple values in the same attribute.

  8. Bitmap index - Wikipedia

    en.wikipedia.org/wiki/Bitmap_index

    A bitmap index is a special kind of database index that uses bitmaps.. Bitmap indexes have traditionally been considered to work well for low-cardinality columns, which have a modest number of distinct values, either absolutely, or relative to the number of records that contain the data.

  9. Raising and lowering indices - Wikipedia

    en.wikipedia.org/wiki/Raising_and_lowering_indices

    Concretely, in matrix notation these can be thought of as row vectors, which give a number when applied to column vectors. We denote this by V ∗ := Hom ( V , K ) {\displaystyle V^{*}:={\text{Hom}}(V,K)} , so that α ∈ V ∗ {\displaystyle \alpha \in V^{*}} is a linear map α : V → K {\displaystyle \alpha :V\rightarrow K} .