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SQL/XML or XML-Related Specifications is part 14 of the Structured Query Language (SQL) specification. In addition to the traditional predefined SQL data types like NUMERIC, CHAR, TIMESTAMP, ... it introduces the predefined data type XML together with constructors, several routines, functions, and XML-to-SQL data type mappings to support ...
Savepoints are defined in the SQL standard and are supported by all established SQL relational databases, including PostgreSQL, Oracle Database, Microsoft SQL Server, MySQL, IBM Db2, SQLite (since 3.6.8), Firebird, H2 Database Engine, and Informix (since version 11.50xC3).
In analogy with relational databases, a column family is as a "table", each key-value pair being a "row". Each column is a tuple consisting of a column name, a value, and a timestamp. In a relational database table, this data would be grouped together within a table with other non-related data. Two types of column families exist:
SQL includes operators and functions for calculating values on stored values. SQL allows the use of expressions in the select list to project data, as in the following example, which returns a list of books that cost more than 100.00 with an additional sales_tax column containing a sales tax figure calculated at 6% of the price.
A current version is maintained for the table, or possibly a group of tables. This is stored in a supporting construct such as a reference table. When a change capture occurs, all data with the latest version number is considered to have changed. Once the change capture is complete, the reference table is updated with a new version number.
In this case, if the transaction's timestamp is after the object's read timestamp, the read timestamp is set to the transaction's timestamp. If a transaction wants to write to an object, but the transaction started before the object's read timestamp it means that something has had a look at the object, and we assume it took a copy of the object ...
Each cell of a bigtable can have zero or more timestamped versions of the data. Another function of the timestamp is to allow for both versioning and garbage collection of expired data. Tables are split into multiple tablets – segments of the table are split at certain row keys so that each tablet is a few hundred megabytes or a few gigabytes ...
As of MySQL 8.0.28, released in January 2022, the functions FROM_UNIXTIME(), UNIX_TIMESTAMP(), and CONVERT_TZ() handle 64-bit values on platforms that support them. This includes 64-bit versions of Linux, macOS, and Windows. [32] [33] In older versions, built-in functions like UNIX_TIMESTAMP() will return 0 after 03:14:07 UTC on 19 January 2038 ...