Il semblerait que la base de données se trouve dans la base de données africaine , mais en lisant une authentique base de données de la littérature technique (que les traducteurs russes traduisaient traditionnellement sous le nom de SGBD - système de gestion de base de données) , je n'ai jamais vu ce terme - SGBD - ne pas avoir vu (n'exclut pas que mal vu , mais par golly je ne mens pas) .
Alors, ce terme est-il inventé? Et combien de bricolage?
Dans cette publication, j'ai rassemblé dans diverses publications informatiques d'auteurs anglophones le soi-disant «champ sémantique» autour du terme base de données - quelles sont les bases de données, de quoi elles sont faites et avec quoi elles mangent . Il me semblait que ce serait clairement plus évident et plus fiable que les glossaires habituels. Bien sûr, vous décidez.
Alors allons-y.
Quels sont-ils?
Les bases de données d'objets sont apparues à la fin des années 1980 - début des années 1990 et sont à nouveau démodées.
Les bases de données d'objets vont et viennent à la fin des années 80 et au début des années 90. Les bases de données XML sont
apparues au début des années 2000 , mais n'ont trouvé qu'une application étroite. Les bases de données XML sont apparues au début des années 2000, mais n'ont connu qu'une adoption de niche.
NoSQL…
There are several driving forces behind the adoption of NoSQL databases…
…JSON. , , XML. , MongoDB, RethinkDB, CouchDB Espresso.
JSON has the appeal of being much simpler than XML. Document-oriented databases like MongoDB, RethinkDB, CouchDB, and Espresso support this data model.
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In document databases, joins are not needed for one-to-many tree structures, and support for joins is often weak.
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Query optimizers for relational databases are complicated beasts, and they have consumed many years of research and development effort
2.3 Cypher, . 2.5 .
Example 2-3 shows the Cypher query to insert the lefthand portion of Figure 2-5 into a graph database
OLTP : .
In most OLTP databases, storage is laid out in a row-oriented fashion: all the values from one row of a table are stored next to each other.
, , . .
Many datasets are simply not that big, so it’s quite feasible to keep them entirely in memory, potentially distributed across several machines. This has led to the development of in-memory databases.
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Similar to concurrency control in a multiuser database environment, locking requires that before the value of a global variable can be used or updated, the variable must be «checked out.»
, , , ( ) , . , , GenBank.
Researchers working with genome data often need to perform sequence-similarity searches, which means taking one very long string (representing a DNA molecule) and matching it against a large database of strings that are similar, but not identical. None of the databases described here can handle this kind of usage, which is why researchers have written specialized genome database software like GenBank.
, BitTorrent, .
Many peer-to-peer systems, such BitTorrent, do not have any central database of content.
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This lookup process can be repeated indefinitely to build up a large local database of what is out there.
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All of the above applications involve interactions between a person and a remote database full of information.
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Why should you, as an application developer, care how the database handles storage and retrieval internally?
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Full-text search is arguably a kind of data model that is frequently used alongside databases.
db_set , , , .
Similarly to what db_set does, many databases internally use a log, which is an append-only data file.
SQL Server — .
A restore scenario in SQL Server is the process of restoring data from one or more backups and then recovering the database.
SQL Server CREATE , .
In SQL Server, CREATE statement creates a new database and the files used and their filegroups.
SQL Server ALTER , .
In SQL Server, ALTER statement modifies a database, or the files and filegroups associated with the database.
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A dropped database can be re-created only by restoring a backup.
SQL Server. , .
Dropping a database deletes the database from an instance of SQL Server and deletes the physical disk files used by the database.
(. .: «» «» , :
— ALTER DROP ;
— UPDATE DELETE ).
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If you make a mistake, you can use the snapshot to recover by reverting the database to the snapshot.
(. : , — « » — restore. ( ) - — recover).
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Reverting is potentially much faster for this purpose than restoring from a backup; however, you cannot roll forward afterward.
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Using one class to read from and write to a database is a form of centralized control.
PHP- Web- .
It [PHP] can be embedded in Web pages to access and present database information.
SQL «-» , .
SQL is the de facto standard language for querying, updating, and managing relational databases.
, ?
How would they feel if that database was suddenly corrupted?
… within_recursive ( ).
… the within_recursive predicate can tell us all the locations in North America (or any other location name) contained in our database.
, .
Instead, each user maintains his own database locally and provides a list of other nearby people who are members of the system.
: .
In order to efficiently find the value for a particular key in the database, we need a different data structure: an index.
SQL Server.
The supported restore scenarios depend on the recovery model of the database and the edition of SQL Server.
— , , , , , .
A recovery model is a database property that controls how transactions are logged, whether the transaction log requires (and allows) backing up, and what kinds of restore operations are available.
SQL Server Database Engine .
For most restore scenarios, it is necessary to apply a transaction log backup and allow the SQL Server Database Engine to run the recovery process for the database to be brought online.
— , SQL Server - () .
Recovery is the process used by SQL Server for each database to start in a transactionally consistent — or clean — state.
— , , , , , .
The desire to hide implementation details is a wonderful reason to create a class whether the details are as complicated as a convoluted database access or as mundane as whether a specific data member is stored as a number or a string.
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Refactorings that involve class or routine interface changes, database schema changes, or changes to boolean tests, among others, tend to be more risky.
[ ] , . .
A data dictionary is a database that describes all the significant data in a project. In many cases, the data dictionary focuses primarily on database schemas.
…
Errors can include <…> improperly designing database tables…
, .
Code-generating tools tend to focus on database applications, but that includes a lot of applications.
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The architecture should describe a plan for managing scarce resources such as database connections, threads, and handles.
, , , , , . .
The architecture should describe how the system will address growth in number of users, number of servers, number of network nodes, number of database records, size of database records, transaction volume, and so on.
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Is the database organization and content specified?
, .frm ( ) , .
Consequently, I adopted a design convention that the .frm file (the form file) was allowed only to retrieve data from the database and store data back into the database. It wasn’t allowed to communicate that data directly to other parts of the program.
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They [subsystems] make it easy to change the database design structure without changing most of the program.
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A design question like «Will this database framework work?» does not provide enough direction for prototyping.
.
You don’t even need to know the database specifics.
CSS XSL/ XPath, , .
We also touched on CSS and XSL/XPath, which aren’t database query languages but have interesting parallels.
… , .
… data processing was changing from a computer-centered view of information systems to a database-centered view.
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The change was to focus on a pool of data on which the computer happened to act (a database-oriented view).
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You might also use prebuilt libraries of container classes, scientific functions, user interface classes, and database-manipulation classes.
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To get Finance the data they need, we may have to cobble together some custom reports, which means bringing in the application developers or database people.
Oracle…
Upgrade thirty-five instances of Oracle databases…
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But Wes says, “That’s not a change! That’s just running a database script.
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Before that change request would even come to us, I would expect him to get the nod from the application and database owners, and also the business.
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A declarative query language … hides implementation details of the database engine, which makes it possible for the database system to introduce performance improvements without requiring any changes to queries.
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:
- Code Complete by Steve McConnell
- Computer networks by Andrew Tannenbaum
- Conception d'applications gourmandes en données par Martin Kleppmann
- Le projet Phoenix de Gene Kim
- Documentation Microsoft SQL , etc.
PS Déjà après la publication, mes collègues et moi avons découvert que le SGBD n'a pas attiré mon attention car le terme est légèrement dépassé et n'est presque jamais utilisé dans la nouvelle littérature sur les bases de données. Dans la vieille littérature - tout le temps. Désolé.