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SQLAlchemy offers tools for database schema generation, querying, and object-relational mapping. Key features include: A comprehensive embedded domain-specific language for SQL in Python called "SQLAlchemy Core" that provides means to construct and execute SQL queries. A powerful ORM that allows the mapping of Python classes to database tables.
There are graphical and command line utilities in Windows, Linux, and Mac OS X environments. Zen Control Center (CC) is the main utility that enables the user to create and manipulate databases and tables, to access servers and clients, to set configurations and properties, and to edit data. Through CC, the user can access a series of other ...
This can be checked by running the "md5sum" command on the files downloaded. Given their sizes, this may take some time to calculate. Due to the technical details of how files are stored, file sizes may be reported differently on different filesystems, and so are not necessarily reliable. Also, corruption may have occurred during the download ...
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 ...
That is the domain of the physical schema. Now logical schemas describe data in terms of relational tables and columns , object-oriented classes , and XML tags . A single set of tables, for example, can be implemented in numerous ways, up to and including an architecture where table rows are maintained on computers in different countries.
The primary front-end for PostgreSQL is the psql command-line program, which can be used to enter SQL queries directly, or execute them from a file. In addition, psql provides a number of meta-commands and various shell-like features to facilitate writing scripts and automating a wide variety of tasks; for example tab completion of object names ...
A schema migration is performed on a database whenever it is necessary to update or revert that database's schema to some newer or older version. Migrations are performed programmatically by using a schema migration tool. When invoked with a specified desired schema version, the tool automates the successive application or reversal of an ...
The database schema is the structure of a database described in a formal language supported typically by a relational database management system (RDBMS). The term " schema " refers to the organization of data as a blueprint of how the database is constructed (divided into database tables in the case of relational databases ).