selectivity

1We haven't found any convincing evidence that selectivity or prestige matters.我們還沒有找到任何有説服力的證據來證明選擇性或聲望很重要。

2Schools are tending towards greater selectivity.學校對新生的選拔有趨嚴之勢。《牛津詞典》

3Selectivity is key to its success.選擇性是成功關鍵。

4Step 2.5: Verify the selectivity estimates步驟 2.5：驗證選擇性估計

5The selectivity of a predicate is defined as.謂詞的選擇性定義如下。

6The first bucket of gold can make her life full of selectivity.這第一桶金，讓生活的可選擇性豐富極了。

7Histograms are used to calculate the selectivity of the predicates.直方圖用於計算謂詞的選擇率。

8This suggests a much better predicate selectivity than it appears to be!這表明謂詞選擇性比其表現出來的還要好！

9The Listing 7 output is starting to look useful, but suffers from a lack of selectivity.清單7的輸出看起來有用一些了，但是缺少選擇性。

10Our ears have only evolved to respond to sound with very high sensitivity and high selectivity.人類的耳朵對聲音的反應，極為敏感，也極有選擇性。

11In other words, the optimizer overestimated the selectivity of the local predicates on the table.換句話説，優化器過高估計了本地謂詞對錶格的選擇性。

12The optimizer can use data distributions to calculate selectivity for the filters in a query.優化器可以使用數據分佈來計算查詢中過濾器的選擇率。

13Given accurate statistics, the query optimizer generally comes up with correct selectivity estimates.如果有了準確的統計信息，那麼查詢優化器一般能夠得出正確的選擇性估計。

14YUSHAN YAN: "in terms of sensitivity and selectivity, the current technology out there is still inferior."嚴教授：“在靈敏度和選擇性方面，目前的技術仍存在劣勢。”

15Now that you've analyzed the selectivity of the local predicates, let's now look at the table selectivity.已經分析了本地謂詞的選擇性，我們再看看錶的選擇性。

16So it is obvious that the accuracy of selectivity estimation depends upon how often you run UPDATE STATISTICS.因此，選擇性估算的準確性顯然基於您運行UPDATE STATISTICS的頻率。

17The use of column groups provides more accurate estimates of the joint selectivity of multiple predicates.列組的使用將給多個謂詞的聯合選擇提供更準確的估計。

18But the selectivity calculated in this way is not as accurate as selectivity calculated using data distribution.但是，使用該方式計算的選擇性不如使用數據分佈計算的選擇性準確。

19Let me count the ways: First, graduation rates rise with college selectivity, even among equally qualified students.讓我們盤點一下這些方法：首先，名牌大學的畢業率隨着學校的知名度而逐次升高。

20Each join reduces the size of the fact table by one-tenth due to selectivity of the table filter on each dimension table.由於每個維度表過濾的選擇度，每次連接都會減少事實表大小的十分之一。

21The selectivity is a value between 0 and 1 that indicates the percentage of rows within the table that the filter can pass.選擇率是介於 0 到 1 之間的一個值，表示表中能通過過濾器的行所佔的百分比。

22On its own, that's pretty powerful; but XPath offers quite a bit more in terms of selectivity, all using what's called a predicate.這本身已經非常強大了，不過 XPath 還提供了更多的選擇性，即使用所謂的謂詞。

23The optimizer USES data distribution information generated by UPDATE STATISTICS to calculate selectivity for the filters in the query.優化器使用UPDATE STATISTICS所生成的數據分佈信息來計算查詢中篩選器的選擇性。

24At the same time, we also have found differences in signal selectivity that may allow us to target some bacteria while ignoring others.同時，我們還發現了信號選擇性的差異，這能夠使我們針對一些特定的細菌而不影響到其他。

25The performance improvement depends on the selectivity of the filter on the dimension table from which the join keys are pushed down.性能的提高取決於連接鍵被下推時所在維度表的過濾選擇度。

26The optimizer can then compare the input variable values to catalog statistics and compute a better selectivity estimate for predicates.然後，優化器可以將輸入變量的值與編目統計進行比較，併為謂詞計算出一個更好的選擇估計。

27However, in the absence of data distributions, the database server calculates selectivity for filters of different types based on table indexes.但是，如果沒有數據分佈，則數據庫服務器根據表索引計算不同類型的過濾器的選擇率。

28And each node is annotated by statistics, estimated costs, selectivity information and so forth that are used to determine the access plan flow.每個節點都有統計數據、評估成本、選擇信息等用來確定訪問計劃流的註釋。 ^[1]