|Оценка пользователей:||(4,1 из 5)|
|Проверен Dr.Web:||Вирусов нет|
2 operating system in 1989 — and extends to driver Sql Server 1c current day. The RTM version is 14.
It is intended as a replacement for MSDE. Two additional editions provide a superset of features not in the original Express Edition. The compact edition is an embedded database engine.
It is limited to 4 GB maximum database size and cannot be run as a Windows service, Compact Edition must be hosted by the application using it. 5 version includes support for ADO. Starting early 2016, Microsoft made this version free of charge to the public.
It can also be used as an embedded database. HP base on the Fast Track architecture. Intended for use as an application component, it did not include GUI management tools.
Later, Microsoft also made available a web admin tool. Had workload or connection limits like MSDE, but no database size limit. Initially designed and developed by Sybase Inc.
IP, named pipes, and shared memory. Data storage is a database, which is a collection of tables with typed columns. In addition to tables, a database can also contain other objects including views, stored procedures, indexes and constraints, along with a transaction log. The data in the database are stored in primary data files with an extension .
Secondary data files, identified with a . Log files are identified with the . Storage space allocated to a database is divided into sequentially numbered pages, each 8 KB in size.
Полный анализ на «Driver Sql Server 1c»
A sql is marked with driver 96-byte header which stores metadata about the page including the page number, page type, free space on the page server the 1c of the object that owns it. Page type defines the data contained in the page: data stored in the database, index, allocation map which holds information about how pages are allocated to tables and indexes, change map which holds information about the changes made to other pages since last backup or logging, or contain large data types such as image or text.
O operation, space is actually managed in terms of an extent which consists of 8 pages. A row in a database table cannot span more than one page, so is limited to 8 KB in size. A table is split into multiple partitions in order to spread a database over a computer cluster. Rows in each partition are stored in either B-tree or heap structure.
If the table has an associated, clustered index to allow fast retrieval of rows, the rows are stored in-order according to their index values, with a B-tree providing the index. The data is in the leaf node of the leaves, and other nodes storing the index values for the leaf data reachable from the respective nodes. If the index is non-clustered, the rows are not sorted according to the index keys. An indexed view has the same storage structure as an indexed table.
A table without a clustered index is stored in an unordered heap structure. However, the table may have non-clustered indices to allow fast retrieval of rows.
In some situations the heap structure has performance advantages over the clustered structure. Both heaps and B-trees can span multiple allocation units. Any 8 KB page can be buffered in-memory, and the set of all pages currently buffered is called the buffer cache.
The buffer cache is managed by the Buffer Manager. Either reading from or writing to any page copies it to the buffer cache. Subsequent reads or writes are redirected to the in-memory copy, rather than the on-disc version.
The page is updated on the disc by the Buffer Manager only if the in-memory cache has not been referenced for some time. Each page is written along with its checksum when it is written. When reading the page back, its checksum is computed again and matched with the stored version to ensure the page has not been damaged or tampered with in the meantime. As such, it needs to control concurrent access to shared data, to ensure data integrity—when multiple clients update the same data, or clients attempt to read data that is in the process of being changed by another client.
Locks can be either shared or exclusive. Exclusive lock grants the user exclusive access to the data—no other user can access the data as long as the lock is held. Shared locks are used when some data is being read—multiple users can read from data locked with a shared lock, but not acquire an exclusive lock. The latter would have to wait for all shared locks to be released.
Locks can be applied on different levels of granularity—on entire tables, pages, or even on a per-row basis on tables. For indexes, it can either be on the entire index or on index leaves. The level of granularity to be used is defined on a per-database basis by the database administrator.
While a fine-grained locking system allows more users to use the table or index simultaneously, it requires more resources, so it does not automatically yield higher performance. The Lock Manager maintains an in-memory table that manages the database objects and locks, if any, on them along with other metadata about the lock. Access to any shared object is mediated by the lock manager, which either grants access to the resource or blocks it.