本文主要介紹sqlserver全文索引(數(shù)據(jù)庫全文索引)的缺點(diǎn)，下面一起看看sqlserver全文索引(數(shù)據(jù)庫全文索引)的缺點(diǎn)相關(guān)資訊。
全文檢索可以檢索varchar類型的文本和圖像字段，但是一個(gè)表最多只能建立一個(gè)全文索引。sql server 2000為存儲(chǔ)在圖像列中的這些類型的數(shù)據(jù)引入了全文檢索功能。如果沒有全文索引，那么字符的模糊查詢只能在基表上掃描完整的表(或索引掃描)。執(zhí)行模糊查詢需要完整的表掃描或索引掃描來表示大量的io。如果模糊查詢頻繁出現(xiàn)，數(shù)據(jù)庫的性能就會(huì)下降。為了簡單起見，這是一個(gè)非常完整和高效的varchar字段全文索引。創(chuàng)建和維護(hù)的過程。1.在企業(yè)管理器中展開數(shù)據(jù)庫以建立全文索引，右鍵單擊全文目錄，并選擇一個(gè)新的全文目錄，如圖1所示。您可以將全文目錄放在單獨(dú)的磁盤或磁盤陣列上以提高效率，從而修改全文目錄的路徑。建議整個(gè)全文目錄不要以任何形式填充和調(diào)度。圖1 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = 2:接下來，將全文索引添加到特定的表中。全文索引不能建立在視圖上，而只能建立在具有唯一索引(主鍵和唯一索引)的基表上。圖2展示了如何在表上構(gòu)建全文索引。構(gòu)建t_fulltext表和初始化數(shù)據(jù)進(jìn)行演示的腳本如下:創(chuàng)建表t_fulltext(排除identity (1，1)和varchar(256)不為空的標(biāo)題，writ:29)。t_fullt:10))插入t _ full t:43))插入t_fullt:02))并插入t_fullt:07))插入t_fullt:33))插入t_fullt:30))插入t_fullt:30))插入t_fullt:03)實(shí)質(zhì)性操作)插入t _ full t:30))插t .珠三角地區(qū)海水比去年低(15:12))。插入t_fullt:44))插入t_fullt:30))插入t _ full t:56))并插入t _ full t:27))插了t_fulltext的值(省媒體說當(dāng)局)。圖2 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = 3:歡迎界面外觀如圖3所示。圖3 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = 4:選擇唯一的全文索引。index，如圖4 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = 5:所選全文索引的列。注意，一個(gè)表只能創(chuàng)建一個(gè)完整的文本索引。;不要選擇不好的語言。通過操作sp _ configure 默認(rèn)全文語言，可以看看默認(rèn)的詞，比如我機(jī)器上運(yùn)行的一個(gè)吧。config_value的值是2052，代表簡體中文。其他代碼表示的語言可以參考網(wǎng)絡(luò)圖書的默認(rèn)全文關(guān)鍵詞。因?yàn)閟ql server對(duì)中文分詞不是很清楚，所以可以 不要依賴sql server給你帶來非常智能的搜索。這意味著全文搜索結(jié)果可能包含意外記錄，或者您希望出現(xiàn)的記錄沒有出現(xiàn)。圖5 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = 6:將表分配給全文目錄，如圖6所示。您還可以通過該界面創(chuàng)建新的目錄。圖6 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = 7:接下來我們會(huì)提示表格填寫時(shí)間表。為了實(shí)時(shí)地將基表全文索引列應(yīng)用于全文索引，我們建議使用下面描述的其他方法進(jìn)行索引維護(hù)。如圖7，建議這里不要添加任何日程，直接點(diǎn)擊下一步。如果不修改數(shù)據(jù)，則在完全填充后不會(huì)添加其他類型的表級(jí)填充。如果執(zhí)行到這一步，并且沒有添加更多的表計(jì)劃，則基本表數(shù)據(jù)的更新將不會(huì)更新到全文索引。圖7 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = 8:在完成界面點(diǎn)擊完成提示，如圖8。請(qǐng)等到下一個(gè)界面出現(xiàn)。圖8 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = 9:在界面點(diǎn)擊確定，如圖9。由于沒有向表中添加時(shí)間表，因此需要設(shè)置時(shí)間表。圖9 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = 10:在企業(yè)資源管理器中點(diǎn)擊f_fulltext的表格，如圖10所示，選擇變更跟蹤。選擇更改跟蹤后，基表數(shù)據(jù)的后期修改可以反映在全文索引中。特別說明:一旦選擇了變更跟蹤，根據(jù)經(jīng)驗(yàn)，確實(shí)需要完成表的完全填充。如果是在線全文索引數(shù)據(jù)庫，選擇變更跟蹤會(huì)導(dǎo)致性能快速下降，從而導(dǎo)致全文索引。它不 不工作。圖10 = = = = = = = = = = = = == = = = = = = = = = = = = = = 11:在企業(yè)資源管理器中點(diǎn)擊f_fulltext的表格，如圖11所示，在后臺(tái)選擇索引更新。通過這一步，全文索引就完成了。因?yàn)槲覀冞x擇了變更跟蹤，所以表的完全填充實(shí)際上已經(jīng)開始了。根據(jù)經(jīng)驗(yàn)，300萬個(gè)全文索引字段長度為50，完成完整填充需要8到10個(gè)小時(shí)。圖11 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = 12:我們可以雙擊全文目錄中的全文索引來查看全文目錄的屬性。如圖12所示，狀態(tài)為idle，項(xiàng)目計(jì)數(shù)大于0，這意味著完全填充已經(jīng)完成。圖12 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = 13:如何查詢?nèi)乃饕?簡要介紹)，建議使用contains和freetext謂詞。如果關(guān)鍵字僅包含干擾詞(有關(guān)干擾詞的信息，請(qǐng)參考在線干擾詞關(guān)鍵字)。select * from t_fulltext其中包含(title，3英尺)將報(bào)告以下錯(cuò)誤服務(wù)器:消息7619，級(jí)別16，狀態(tài)1，第1行全文操作失敗。查詢子句只包含被忽略的單詞。使用下面的語法，可以避免錯(cuò)誤，真正查詢到正確的記錄。select * from t_fulltext，包含(title，× 3x) 13省媒體稱，陳 的講話會(huì)唱一首老歌(15 : 30)2005-12-31 23:17: 17.670 10北京公安系統(tǒng)今天全部停查五r ing(17: 30)2005-12-31 23 : 17 : 17.653 17評(píng)論:取消農(nóng)業(yè)稅使能夠分享經(jīng)濟(jì)增長的成果(17 echo 0手術(shù)第一天突發(fā)(17 : 30)2005年12月31日，23:17: 8名患者在福建、廣西死亡，患者200人(17:33)。5-12-31 23:17: 17.653(影響行數(shù)為5)全文索引在此簡單介紹一下，希望能起到作用。
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