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The fundamental unit of data storage in SQL Server is the page. The disk space allocated to a data file (.mdf or .ndf) in a database is logically divided into pages numbered contiguously from 0 to n. Disk I/O operations are performed at the page level. That is, SQL Server reads or writes whole data pages.
Extents are a collection of eight physically contiguous pages and are used to efficiently manage the pages. All pages are organized into extents.
Take a regular book: all content in it is written on pages. Similar to a book, in SQL Server all the data rows are written on pages. In a book, all pages are the same physical size. Similarly, in SQL Server all data pages are the same size - 8 kilobytes. In a book most pages contain the data - the main content of the book - and some pages contain metadata about the content - for example table of contents and index. Again, SQL Server is not different: most pages contain actual rows of data which were stored by users these are called Data pages and text/image pages (for special cases). The Index pages contain index references about where the data is and finally there are system pages that store variety of metadata about the organization of the data (PFS, GAM, SGAM, IAM, DCM, BCM pages). See table below for page types and their description.
As mentioned, in SQL Server, the page size is 8-KB. This means SQL Server databases have 128 pages per megabyte. Each page begins with a 96-byte header that is used to store system information about the page. This information includes the page number, page type, the amount of free space on the page, and the allocation unit ID of the object that owns the page.
The following table shows the page types used in the data files of a SQL Server database.
|Data||Data rows with all data, except text, ntext, image, nvarchar(max), varchar(max), varbinary(max), and xml data, when text in row is set to ON.|
|Text/Image||Large object data types: (text, ntext, image, nvarchar(max), varchar(max), varbinary(max), and xml data) |
Variable length columns when the data row exceeds 8 KB: (varchar, nvarchar, varbinary, and sql_variant)
|Global Allocation Map, Shared Global Allocation Map||Information about whether extents are allocated.|
|Page Free Space (PFS)||Information about page allocation and free space available on pages.|
|Index Allocation Map||Information about extents used by a table or index per allocation unit.|
|Bulk Changed Map||Information about extents modified by bulk operations since the last BACKUP LOG statement per allocation unit.|
|Differential Changed Map||Information about extents that have changed since the last BACKUP DATABASE statement per allocation unit.|
Log files do not contain pages they contain a series of log records.
Data rows are put on the page serially, starting immediately after the header. A row offset table starts at the end of the page, and each row offset table contains one entry for each row on the page. Each row offset entry records how far the first byte of the row is from the start of the page. Thus, the function of the row offset table is to help SQL Server locate rows on a page very quickly. The entries in the row offset table are in reverse sequence from the sequence of the rows on the page.
Large Row Support
Rows cannot span pages, however portions of the row may be moved off the row's page so that the row can actually be very large. The maximum amount of data and overhead that is contained in a single row on a page is 8,060 bytes (8-KB). However, this does not include the data stored in the Text/Image page type.
This restriction is relaxed for tables that contain varchar, nvarchar, varbinary, or sql_variant columns. When the total row size of all fixed and variable columns in a table exceeds the 8,060-byte limitation, SQL Server dynamically moves one or more variable length columns to pages in the ROW_OVERFLOW_DATA allocation unit, starting with the column with the largest width.
This is done whenever an insert or update operation increases the total size of the row beyond the 8,060-byte limit. When a column is moved to a page in the ROW_OVERFLOW_DATA allocation unit, a 24-byte pointer on the original page in the IN_ROW_DATA allocation unit is maintained. If a subsequent operation reduces the row size, SQL Server dynamically moves the columns back to the original data page.
As mentioned earlier, a row cannot reside on multiple pages and can overflow if the combined size of variable-length data-type fields exceeds the 8060-byte limit. To illustrate, a table may be created with two columns: one varchar(7000) and another varchar (2000). Individually neither column exceeds the 8060-byte, but combined they could do so, if the entire width of each column is filled. SQL Server may dynamically move the varchar(7000) variable length column to pages in the ROW_OVERFLOW_DATA allocation unit. When you combine varchar, nvarchar, varbinary, sql_variant, or CLR user-defined type columns that exceed 8,060 bytes per row, consider the following:
- Moving large records to another page occurs dynamically as records are lengthened based on update operations. Update operations that shorten records may cause records to be moved back to the original page in the IN_ROW_DATA allocation unit. Querying and performing other select operations, such as sorts or joins on large records that contain row-overflow data slows processing time, because these records are processed synchronously instead of asynchronously.
Therefore, when you design a table with multiple varchar, nvarchar, varbinary, sql_variant, or CLR user-defined type columns, consider the percentage of rows that are likely to flow over and the frequency with which this overflow data is likely to be queried. If there are likely to be frequent queries on many rows of row-overflow data, consider normalizing the table so that some columns are moved to another table. This can then be queried in an asynchronous JOIN operation.
- The length of individual columns must still fall within the limit of 8,000 bytes for varchar, nvarchar, varbinary, sql_variant, and CLR user-defined type columns. Only their combined lengths can exceed the 8,060-byte row limit of a table.
- The sum of other data type columns, including char and nchar data, must fall within the 8,060-byte row limit. Large object data is also exempt from the 8,060-byte row limit.
- The index key of a clustered index cannot contain varchar columns that have existing data in the ROW_OVERFLOW_DATA allocation unit. If a clustered index is created on a varchar column and the existing data is in the IN_ROW_DATA allocation unit, subsequent insert or update actions on the column that would push the data off-row will fail. For more information about allocation units, see Table and Index Organization.
- You can include columns that contain row-overflow data as key or nonkey columns of a nonclustered index.
- The record-size limit for tables that use sparse columns is 8,018 bytes. When the converted data plus existing record data exceeds 8,018 bytes, MSSQLSERVER ERROR 576 is returned. When columns are converted between sparse and nonsparse types, Database Engine keeps a copy of the current record data. This temporarily doubles the storage that is required for the record.
- To obtain information about tables or indexes that might contain row-overflow data, use the sys.dm_db_index_physical_stats dynamic management function.
Extents are the basic unit in which space is managed. An extent is eight physically contiguous pages, or 64 KB. This means SQL Server databases have 16 extents per megabyte.
SQL Server has two types of extents:
- Uniform extents are owned by a single object all eight pages in the extent can only be used by the owning object.
- Mixed extents are shared by up to eight objects. Each of the eight pages in the extent can be owned by a different object.
Up to, and including, SQL Server 2014 (12.x), SQL Server does not allocate whole extents to tables with small amounts of data. A new table or index generally allocates pages from mixed extents. When the table or index grows to the point that it has eight pages, it then switches to use uniform extents for subsequent allocations. If you create an index on an existing table that has enough rows to generate eight pages in the index, all allocations to the index are in uniform extents.
Starting with SQL Server 2016 (13.x), the default for most allocations in a user database and tempdb is to use uniform extents, except for allocations belonging to the first eight pages of an IAM chain. Allocations for master, msdb, and model databases still retain the previous behavior.
Up to, and including, SQL Server 2014 (12.x), trace flag 1118 can be used to change the default allocation to always use uniform extents. For more information about this trace flag, see DBCC TRACEON - Trace Flags.
Starting with SQL Server 2016 (13.x), the functionality provided by TF 1118 is automatically enabled for tempdb and all user databases. For user databases, this behavior is controlled by the SET MIXED_PAGE_ALLOCATION option of ALTER DATABASE , with the default value set to OFF, and trace flag 1118 has no effect. For more information, see ALTER DATABASE SET Options (Transact-SQL).
Starting with SQL Server 2012 (11.x), the sys.dm_db_database_page_allocations system function can report page allocation information for a database, table, index, and partition.
The sys.dm_db_database_page_allocations system function is not documented and is subject to change. Compatibility is not guaranteed.
Starting with SQL Server 2019 (15.x), the sys.dm_db_page_info system function is available and returns information about a page in a database. The function returns one row that contains the header information from the page, including the object_id, index_id, and partition_id. This function replaces the need to use DBCC PAGE in most cases.
Tarot History Forum
Engage in your favorite "Unicorn Hunt" in this unstuffy area for playful historical pondering.
For the exclusive use of studying the iconography of tarot cards. Each trump has its own thread, allowing detailed exploration from a variety of sources.
The Exhibition Gallery
The place for the exploration, comparison, and discussion of historical tarot decks (rather than individual cards) and other historical documents.
The Plush Parlor
An area for the discussion of esoteric tarot.
The Library (West Wing)
Links to Tarot History related Websites and Pages.
The Library (East Wing)
Links to Tarot History related Books and Articles.
The Library (North Aisle)
Links to Tarot History related Workshops, Conventions and Events.
The Staff Servants
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Most users ever online was 1228 on 15 Jan 2020, 15:52
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The Tarot History forum was established in 2008 as a comfortable and welcoming forum for enthusiasts to explore the birth and development of tarot.
As a history forum, we expect a certain level of academic engagement in our discussions, but we are also aware that our members have their individual interests and objectives, so kindly encourage everyone to be supportive of each other's journeys.
Total posts 22137 Total topics 1199 Total members 527 Our newest member rosele
Oregon Genealogy is being developed as a genealogical and historical resource for your personal use. While the original thought was to provide this website as a resource for finding genealogy and historical data concerning Oregon genealogy and history on the web, we have begun adding specific genealogy data to this site for your personal use.
In an attempt to further expand our offerings and refine your search, we have begun the creation of county websites. Those county sites can be found in the list of links to the right. While only a small portion of Oregon counties are presently listed, the amount of data for those counties is quite impressive. If you have a county web site that you would like to add to these pages, please let us know. We can provide you with Free space for your pages.
The "Search This Site" search on the right side will search all of the Oregon Genealogy website, but will not search the data linked to on offsite pages.
Oregon Genealogy is the home of the American History and Genealogy Project,
if you would like to adopt a county, please visit our pages!! You are welcome to adopt one of the counties on your visit.
What's New in Oregon
By clicking on individual counties you will find more updates.
We provide the highlights here and the individual county pages provide
Say Goodbye to Gary Jaensch
His memory will be kept alive by the amount of information
he contributed to Oregon Genealogy and the information that
will still be put online in the files and folders he left for me
Oregon Historic Cemeteries
Important care of Historic Cemeteries
Baker City and County Schools
Class Photos from many schools around the county
Centennial Pioneer Families of Baker County Oregon Updated
Family Photos of Love, Long, Payton, and Colton Families
Speelman Wagon Train Journey
A first hand account of this family's journey from
Iowa to Baker County, Oregon
Orville Fisher tells it like it was!
Over 23,000 Names, from many states and all Oregon Genealogy Counties
You may submit a query for any County in Oregon
County Updates and New Information
Oregon Genealogy provides Historical and Genealogical information for the following Counties
Their Index pages will show you What's New for each County
Curry and Columbia County, Oregon
Is a new addition to our website, if you have information you would like to
contribute, please use our Contact Page.
Grant, Harney, Malheur and Umatilla
If you would like to contribute information to these counties, or assist in
building these counties, please use our Contact Page.
Wasco County is a new addition to the AHGP
Mark John has done a great job of developing them, stop by for a visit
Be sure to visit our other regional state websites! Each state is unique in it's presentation and data, and who knows which of your ancestors you may find on their pages!
Oregon Obituary Database
We changed our name, and have expanded!
Contains obituaries for Baker, Crook, Grant, Hood River, Lane, Linn, Malheur, Umatilla, Union, and Wallowa Counties.
Lizzie Borden Collection
The Lizzie Borden Collection consists of biographies, nonfiction accounts of the murders and trial, fictionalized retellings of the story, plays, bibliographies, and news articles related to Lizzie Borden, her trial, and the Borden murders. These materials must be used in the library.
The Fall River Historical Society has photographs and artifacts relating to the murders. Images and information can also be found at the Lizzie Borden Bed & Breakfast and the Lizzie Andrew Borden Virtual Museum and Library.
Programming With History Functions
This section describes how to use the History library in other programs.
Introduction to History The programmer using the History library has available functions for remembering lines on a history list, associating arbitrary data with a line, removing lines from the list, searching through the list for a line containing an arbitrary text string, and referencing any line in the list directly. In addition, a history expansion function is available which provides for a consistent user interface across different programs.
The user using programs written with the History library has the benefit of a consistent user interface with a set of well-known commands for manipulating the text of previous lines and using that text in new commands. The basic history manipulation commands are identical to the history substitution provided by bash.
If the programmer desires, he can use the Readline library, which includes some history manipulation by default, and has the added advantage of command line editing.
Before declaring any functions using any functionality the History library provides in other code, an application writer should include the file <readline/history.h> in any file that uses the History library's features. It supplies extern declarations for all of the library's public functions and variables, and declares all of the public data structures.
History Storage The history list is an array of history entries. A history entry is declared as follows:
typedef void * histdata_t The history list itself might therefore be declared as
HIST_ENTRY ** the_history_list
The state of the History library is encapsulated into a single structure: If the flags member includes HS_STIFLED, the history has been stifled.
The Land Office and Survey Office were established in Sabah in the 19th Century and until 1940, both these offices functioned separately where the Land Office is administered by a Commissioner of Lands and the Survey Office is administered by a Surveyor General. From 1940 to 1947, the Land Office and the Survey Office were amalgamated and administered by a single officer known as the Commissioner of Land and Surveyor General. From 1947 until 1954, the Land Office and the Survey Office were once again separated under different administration. Anyway, these two Offices were finally amalgated since 1954 until today administered under a Director of Lands and Surveys and assisted by a Deputy and two Assistant Directors.
The first survey plan was deposited in 1883 and the first title “Country Lease No. 1” was registered in February, 1884 in the District of Kudat.
The former Lands and Surveys Office building in Kota Kinabalu Town became a historic building as the "proclamation" of the then North Borneo including Labuan as a Colony on 15th of July, 1946 took place in this bullet-riddled building. This building is one of the few which survived the 2nd World-War and still intact. It was being used by the then State Government and surrounded by Standard Chartered Bank, Hong Kong & Shanghai Bank, Harrison & Crossfield and the water front.
Until 1913, there were separate Land Registry Offices in Sandakan, Kota Kinabalu, Kudat and Tawau. During 1913 the Central Land Registry was established in the Office of the Commissioner of Lands in Kota Kinabalu and the registration of all titles other than Native Titles began to be done in the Central Land Office. Registration of Native Titles continues to be done in the districts by the Assistant Collector of Land Revenue.
At present, the Land Offices for the districts of Tawau, Lahad Datu, Sandakan, Keningau, Beaufort, Kudat and Kota Kinabalu are administered by Assistant Collector of Land Revenue who are staff of the Lands and Surveys Department and in the remaining 16 districts, the District Officers and Assistant District Officers perform the duties as Assistant Collector of Land Revenue whose main job is to look after land matters at district level. It is anticipated that land administration in all districts in Sabah can eventually be taken over by officers of the Lands and Surveys Department so that that land administration can be done more professionally, effectively and efficiently.
The history and revolution of the Lands and Surveys Department has direct bearing on the history and development of the State since the functions of this department is related to 'land'. Land is a source of all material wealth and the basic requirement of any development, be it agricultural, residential, industrial, commercial or social. The increasing tempo of the State development is the evident of the significant and active role played by the Department in the development mainstream of the State.
The Botswana History Pages are designed for seekers after knowledge about Botswana. There are 2 pages of general history, followed by 13 informative pages with a historical bias - on archaeology, culture, economy, education, geography, language, literature, politics, religion, science, society, tourism, and media.
You can download the complete set of pages as a zip file: see the download page.
- Early Hunting, Pastoralist, and Farming Peoples
- Iron Age Kingdoms and States
- Growth of Tswana States
- A British Protectorate
- Advance to Independence
- Botswana Gains International Standing
- Masire Succeeds Seretse Khama
- Mogae Succeeds Masire
- History Links
- Fine Arts & Crafts
- Music & Drama
- Cultural Institutions
- Sport & Recreation
- Culture Links
- Economic growth
- Mining, water and power
- Manufacturing industries
- International trade
- Transport & tourism
- Economics Links
- Physical Geography
- Internal Regions
- Rural Settlement
- "Traditional" Large Villages & Towns
- "Modern" Towns & Cities
- Geography Links
- Indo-European (English etc.)
- Khoesan (Khoe)
- Khoesan (San)
- Niger-Congo (Tswana etc.)
- Niger-Congo (Yeyi etc.)
- Standard dialects & publication
- Language Links
- President & Vice-President
- Political Parties
- Local Government
- Foreign Policy
- Legal System
- Police & Military
- Science Links
- Social Class
- Daily Life in Villages
- Society Links
- Tourism in Northern/ Western Botswana
- Tourism in Eastern/ Southern Botswana
- Links - Chobe & Okavango Tourism
- Links - General Botswana Tourism
- Appendix: The Missionaries' Road
The Botswana History Pages by Neil Parsons may be freely reproduced, in print or electronically,on condition
(i) that full acknowledgement of the source is made.
(ii) that the use is not for profit
INDEX PAGES - History
2019-07-01: Release 3.0.
This release is the first version of the dynamic website built as part of IUPAC Project 2016-046-1-024. New features include:
- REST style URLs for access to entries (format: https://goldbook.iupac.org/terms/view/ )
- Application Programming Interface (API) for machine access to entry content
- A downloadable vocabulary in multiple formats
- Improved search
- Graphical User Interface (GUI) built using BoostStrap
2017-03-27: Release 2.3.3b.
This release is a stabilized version of the pages in 2.3.3. No entries have been change, however page updates that have been made include
- HTML 5 encoding on all pages
- Removal of broken links/image references
- Google Analytics tracking has been added
- Removal of the structure search, goldify and RSS feed functions (these will be added back in the next revision)
The next revision will be a completely new version of the Gold Book website, with dynamically generated pages and new features, see IUPAC Project 2016-046-1-024 for details.
2010-12-22: Release 2.2.
The main new feature of this release is the introduction of PDF version of Gold Book definitions. PDFs are created from the same source as HTML pages, so 100% correspondence of content should be guaranteed. To download the PDFs, use a link at the bottom of each page. Note: this feature is now in a testing phase. Once it is mature enough, we might give it a more prominent place and consider providing more versions of the PDF output.
In this release, the display of automatically added links was changed to distinguish them visually from links added by authors.
2009-09-07: Release 2.1.5.
This release contained a new service that allows users to try the goldify software online (currently unavailable).
2009-07-03: Release 2.1.2.
This minor update does not include any updates of the actual content of the GoldBook. It features a redesigned index of sum formulas and new resource files related to the software tools introduced in the previous release.
2009-07-02: Release 2.1.1.
This minor update does not include any updates of the actual content of the GoldBook. It features a redesigned index of quantities, improvements of the HTML code structure and a few minor fixes. The most important new feature is the introduction of software tools that enable automatic addition of links to Gold Book terms into text and HTML documents.
2009-03-17: Release 2.0.4.
InChI metadata were updated to the standard InChI and InChIKey.
2008-09-12: Release 2.0.1.
This is maintenance release containing a few fixes in the information about the XML Gold Book project and adding release date to the information on each page. There are no changes in the content.
2006-09-29: Release 1.0.0.
First release published after the review and approval of both IUPAC committees involved (CPEP (now CPCDS) and ICTNS).
2006-09-13: Fifth (and last) preview release (0.5.0). This release contains an updated "about" section and some minor changes in other parts of the site. It is the last preview release before the site will be moved onto the IUPAC website and release 1.0.0 will be made.
2006-09-11: First revision of the fourth public preview release (0.4.1). In this release several minor fixes were introduced throughout the Gold Book. This release also introduces InChIs for all the chemical structures as meta-data inside each entry.
2006-09-01: Fourth public preview release (0.4.0). This release was focused on cleanup of problems discovered during the review process. Most importantly, rendering of symbols of vector quantities was fixed. Also several changes were made throughout the publication, improving usability and consistency.
2006-05-19: Third public preview release (0.3.0). In this release, all new entries submitted by Aubrey Jenkins were added (242 items), sorting of the entries was fixed to match that of the printed version, the HTML code was slightly revised to improve readability and some minor problems were fixed.
2006-04-29: Second public preview release (0.2.0). Almost one-third of the entries were updated from the first preliminary public release. These were mainly small fixes (typically in missing punctuation), but there were also many more serious problems such as missing reactions or formulas. Overall the Gold Book should be now prepared for public review.
Globalization, the ever-increasing interconnectedness of the world, is not a new phenomenon, but it accelerated when western Europeans discovered the riches of the East. During the Crusades (1095–1291), Europeans developed an appetite for spices, silk, porcelain, sugar, and other luxury items from the East, for which they traded fur, timber, and Slavic people they captured and sold (hence the word slave). But when the Silk Road, the long overland trading route from China to the Mediterranean, became costlier and more dangerous to travel, Europeans searched for a more efficient and inexpensive trade route over water, initiating the development of what we now call the Atlantic World.
In pursuit of commerce in Asia, fifteenth-century traders unexpectedly encountered a “New World” populated by millions and home to sophisticated and numerous peoples. Mistakenly believing they had reached the East Indies, these early explorers called its inhabitants “Indians.” West Africa, a diverse and culturally rich area, soon entered the stage as other nations exploited its slave trade and brought its peoples to the New World in chains. Although Europeans would come to dominate the New World, they could not have done so without Africans and native peoples (Figure 1.1).
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Watch the video: TheFatRat - Xenogenesis (July 2022).