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  2. Database index - Wikipedia

    en.wikipedia.org/wiki/Database_index

    Indexes are used to quickly locate data without having to search every row in a database table every time said table is accessed. Indexes can be created using one or more columns of a database table, providing the basis for both rapid random lookups and efficient access of ordered records. An index is a copy of selected columns of data, from a ...

  3. Database catalog - Wikipedia

    en.wikipedia.org/wiki/Database_catalog

    A database catalog of a database instance consists of metadata in which definitions of database objects such as base tables, views (virtual tables), synonyms, value ranges, indexes, users, and user groups are stored. [1] [2] It is an architecture product that documents the database's content and data quality. [3]

  4. Comparison of relational database management systems - Wikipedia

    en.wikipedia.org/wiki/Comparison_of_relational...

    Note (6): Can be implemented using Function-based Indexes in Oracle 8i and higher, but the function needs to be used in the sql for the index to be used. Note (7): A PostgreSQL functional index can be used to reverse the order of a field. Note (10): B+ tree and full-text only for now.

  5. Database engine - Wikipedia

    en.wikipedia.org/wiki/Database_engine

    Database designers can add or remove indexes without changing application logic, reducing maintenance costs as the database grows and database usage evolves. Indexes can speed up data access, but they consume space in the database, and must be updated each time the data is altered. Indexes therefore can speed data access but slow data maintenance.

  6. SQL syntax - Wikipedia

    en.wikipedia.org/wiki/SQL_syntax

    Each column in an SQL table declares the type(s) that column may contain. ANSI SQL includes the following data types. [14] Character strings and national character strings. CHARACTER(n) (or CHAR(n)): fixed-width n-character string, padded with spaces as needed; CHARACTER VARYING(n) (or VARCHAR(n)): variable-width string with a maximum size of n ...

  7. Wikipedia:Database dump import problems - Wikipedia

    en.wikipedia.org/wiki/Wikipedia:Database_dump...

    It seems to have worked. There might be a better way to increase the size of the table here (the db won't import with the default limit of 4Gb) Mr. Jones 13:56, 16 Dec 2004 (UTC) Indeed setting myisam_data_pointer_size to 7 works as well, which seems better. Brighterorange 8 July 2005 16:25 (UTC) Curl appears to also have the 2gb download limit.

  8. Block Range Index - Wikipedia

    en.wikipedia.org/wiki/Block_Range_Index

    A Block Range Index or BRIN is a database indexing technique. They are intended to improve performance with extremely large [i] tables.. BRIN indexes provide similar benefits to horizontal partitioning or sharding but without needing to explicitly declare partitions.

  9. Spatial database - Wikipedia

    en.wikipedia.org/wiki/Spatial_database

    A spatial index is used by a spatial database to optimize spatial queries.Database systems use indices to quickly look up values by sorting data values in a linear (e.g. alphabetical) order; however, this way of indexing data is not optimal for spatial queries in two- or three-dimensional space.