indexing

问题 The PostgreSQL Documentation on arrays provides an example using [-1] to access what appears to be the last element of an array; however while SELECT arr[2:3]; produces {5,9} , arr[2:-1] results in {} . How can the last element of an array be obtained in PostgreSQL? Edit: Windows, PostgreSQL v9.2.1 回答1: I think you're misinterpreting the example. PostgreSQL arrays don't have to be indexed from 1 to n , that's just the default: By default PostgreSQL uses a one-based numbering convention for

问题 I am stuck with my pandas script. Actually , i am working with two csv file(one input and the other output file). i want to copy all the rows of two column and want to make calculation and then copy it to another dataframe (output file). The columns are as follows : 'lat', 'long','PHCount', 'latOffset_1', 'longOffset_1','PH_Lat_1', 'PH_Long_1', 'latOffset_2', 'longOffset_2', 'PH_Lat_2', 'PH_Long_2', 'latOffset_3', 'longOffset_3','PH_Lat_3', 'PH_Long_3', 'latOffset_4', 'longOffset_4','PH_Lat_4

问题 I have a table which stores comma separated values in an NVARCHAR(MAX). I have created a view, which uses string manipulation to convert these comma separated values into an xml list. I can then use this Xml column access each item. The queries on this column will benefit greatly if I could index it. However, on trying to create a Primary XML index I get the message "View XmlFoo foes not have a clustered primary key. Creation of an XML index requires a clustered primary key on the view." Is

问题 I have a large table with millions of records. Table `price` ------------ id product site value The table is brand new, and there are no indexes created. I then issued a request for new index creation with the following query: CREATE INDEX ix_price_site_product_value_id ON price (site, product, value, id); This took long long time, last time I was checking ran for 5000+ seconds, because of the machine. I am wondering if I issue another index creation, will it use the existing index in the

问题 I am using ElasticSearch 1.5.2 and I wish to have the following settings : "settings": { "analysis": { "filter": { "filter_shingle": { "type": "shingle", "max_shingle_size": 2, "min_shingle_size": 2, "output_unigrams": false }, "filter_stemmer": { "type": "porter_stem", "language": "English" } }, "tokenizer": { "my_ngram_tokenizer": { "type": "nGram", "min_gram": 1, "max_gram": 1 } }, "analyzer": { "ShingleAnalyzer": { "tokenizer": "my_ngram_tokenizer", "filter": [ "standard", "lowercase",

问题 There are some other similar question to this but, please, do not confuse. I know there's a function STATS_DATE() to know where the stats where updated, which is fine, but what I want to know is what triggers an update of this stats, or a cut-off. I know there's a report for this as well. But last week I saw the stats in certain server and they gave me very good information with amounts of 4 digits for the main tables in this particular database. Right now looking in the same production

问题 I need to perhaps write a function that just outputs the index of an object inside an array, obviously, using $.inArray returns this just fine in the example below. array = ['one', 'two', 'three']; $.inArray('one', array) // 0 With a more elaborate array, How can I find the index of the objects nested within? array = [ { name: 'One', // index?? data: { title: 'Title One', content: 'Content One' } }, { name: 'Two', data: { title: 'Title Two', content: 'Content Two' } }, { name: 'Three', data:

问题 Given a vector A = [1,2,3,...,100] I want to extract all elements, except every n-th. So, for n=5, my output should be B = [1,2,3,4,6,7,8,9,11,...] I know that you can access every n-th element by A(5:5:end) but I need something like the inverse command. If this doesn't exist I would iterate over the elements and skip every n-th entry, but that would be the dirty way. 回答1: You can eliminate elements like this: A = 1:100; removalList = 1:5:100; A(removalList) = []; 回答2: Use a mask. Let's say

问题 When is it acceptable for an indexer to automatically add items to a collection/dictionary? Is this reasonable, or contrary to best practices? public class I { /* snip */ } public class D : Dictionary<string, I> { public I this[string name] { get { I item; if (!this.TryGetValue(name, out item)) { item = new I(); this.Add(name, item); } return item; } } } Sample of how this may be used in a collection: public class I { public I(string name) {/* snip */} public string Name { get; private set; }

问题 I want to serve my users the most relevant and best results. For example, I'm rewarding records that have a big title, description, attached photos, etc. For context: the records are bicycle routes, having routepoints (coordinates) and metadata like photos, reviews, etc. Now, I have indexed these records using Hibernate and then I search within the index using Lucene in Hibernate Search . To score my results, I build queries based on the document properties and boost them (using boostedTo() )