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  2. Correlated subquery - Wikipedia

    en.wikipedia.org/wiki/Correlated_subquery

    However, in some database systems, it is allowed to use correlated subqueries while joining in the FROM clause, referencing the tables listed before the join using a specified keyword, producing a number of rows in the correlated subquery and joining it to the table on the left.

  3. Shard (database architecture) - Wikipedia

    en.wikipedia.org/wiki/Shard_(database_architecture)

    Horizontal partitioning splits one or more tables by row, usually within a single instance of a schema and a database server. It may offer an advantage by reducing index size (and thus search effort) provided that there is some obvious, robust, implicit way to identify in which partition a particular row will be found, without first needing to search the index, e.g., the classic example of the ...

  4. Column groups and row groups - Wikipedia

    en.wikipedia.org/wiki/Column_groups_and_row_groups

    Short names or notational names include col group or colgroup, and row group or rowgroup. They can have varying uses depending on context: In mathematics, a partitioned matrix is an interpretation of a matrix as being broken down into submatrices which may be more precisely referred to as a collection of row groups and column groups

  5. DUAL table - Wikipedia

    en.wikipedia.org/wiki/DUAL_table

    The DUAL table is a special one-row, one-column table present by default in Oracle and other database installations. In Oracle, the table has a single VARCHAR2(1) column called DUMMY that has a value of 'X'. It is suitable for use in selecting a pseudo column such as SYSDATE or USER.

  6. Oracle Database - Wikipedia

    en.wikipedia.org/wiki/Oracle_Database

    Oracle Database (commonly referred to as Oracle DBMS, Oracle Autonomous Database, or simply as Oracle) is a proprietary multi-model [4] database management system produced and marketed by Oracle Corporation. It is a database commonly used for running online transaction processing (OLTP), data warehousing (DW) and mixed (OLTP & DW) database ...

  7. Partition (database) - Wikipedia

    en.wikipedia.org/wiki/Partition_(database)

    This type of partitioning is also called "row splitting", since rows get split by their columns, and might be performed explicitly or implicitly. Distinct physical machines might be used to realize vertical partitioning: storing infrequently used or very wide columns, taking up a significant amount of memory, on a different machine, for example ...

  8. Data orientation - Wikipedia

    en.wikipedia.org/wiki/Data_orientation

    The two most common representations are column-oriented (columnar format) and row-oriented (row format). [ 1 ] [ 2 ] The choice of data orientation is a trade-off and an architectural decision in databases , query engines, and numerical simulations. [ 1 ]

  9. Help:Sortable tables - Wikipedia

    en.wikipedia.org/wiki/Help:Sortable_tables

    It is easy to use now. It is a template to automatically add row numbers to sortable tables. The row numbers will not be sorted when columns of data are sorted. A possible note to add above a table: Row numbers are static. Other columns are sortable. This allows ranking of any column. See list of articles transcluding {{static row numbers}}.