indexing

问题 In a file with the data in the following structure: # [year] "Town A" population "Town B" population "Town C" population # [year2] "Town A" population "Town B" population "Town C" population # [year3] "Town A" population "Town B" population "Town C" population I have managed to create a histogram using the following: set style data histogram set style histogram columnstacked p 'file.dat' index '[year]' u 2:key(1) ,\ '' index '[year2]' u 2,\ '' index '[year3]' u 2; The previous settings

问题 At blog I see below statement Secondary indexes are a first-class construct in MongoDB. This makes it easy to index any property of an object stored in MongoDB even if it is nested. This makes it really easy to query based on these secondary indexes. Cassandra has only cursory support for secondary indexes. Secondary indexes are also limited to single columns and equality comparisons. I have two related questions on it . Cassandra has only cursory support for secondary indexes. Not sure what

问题 Inside the for loop I'm trying to access the element at index count in CLs (this line of code: echo !!CLs[!count!]!! ) , but I'm not sure how to do this. I don't really understand how expansion works in this case, so what you see below it me trying something out of no where. @ECHO off setlocal enableextensions enabledelayedexpansion SET CLs[0]=# SET /A count = 0 FOR /F "tokens=5" %%I IN ('some command') DO ( echo !!CLs[!count!]!! :: THIS LINE IF NOT %%I == CLs[!count!] ( SET /A count += 1 SET

问题 When Solr build the index, it gets parts of email address. For exemple, if i have an email like this : foo@bar.com, Solr indexes the words "foo" and "barcom". I want to remove theses words but I don't know how to do this. I tried to modify the configuration file schema.xml adding this rule on my indexed field : <filter class="solr.PatternReplaceFilterFactory" pattern=" (.*)@(.*) " replacement=" " replace="all"/> However, it doesn't work. 回答1: You can detect tokens as a e-mailaddress and

问题 As this article's figure 4 says, SQL Server 2005 + can return you a list of missing indexes. It stores 2 important info about missing indexes: [EqualityUsage],[InequalityUsage] If I have a missing index where: [EqualityUsage]='col1',[InequalityUsage]='col2' Should I create an index with Indexed Key Columns: 'col1,col2' or 'col2,col1' ? 回答1: col1, col2 CREATE INDEX To convert the information returned by sys.dm_db_missing_index_details into a CREATE INDEX statement, equality columns should be

问题 I am working on a spreadsheet in which I have ticker id in column B, members corresponding to those tickers in column I and rates in column J. Rates change depending upon the no. of members, so one ticker ids can be in multiple rows. In my output, I need the rate for a particular ticker id and member. It should lookup exact ticker id but if no. of members is not there in data then it should pick the largest value that is less than or equal to lookup_value. I have attached snapshot of the data

问题 I have a dataframe that looks something like this: df Name date season binary Apple 2016-04-24 MAM 1 Banana 2016-05-01 MAM 1 Berry 2016-05-01 MAM 1 Berry 2017-11-05 OND 1 Orange 2016-11-27 OND 1 Kiwi 2017-03-27 MAM 1 And I have a long date time object of a bunch of dates like this: df1 date season Week 2016-03-28 MAM 13 2016-04-04 MAM 14 2016-04-11 MAM 15 2016-04-18 MAM 16 2016-04-25 MAM 17 2016-05-02 MAM 18 2016-05-09 MAM 19 2016-05-16 MAM 20 2016-05-23 MAM 21 2016-05-30 MAM 22 2016-06-06

问题 I have a comment model for each thread, const CommentSchema = new mongoose.Schema({ author: { type: ObjectID, required: true, ref: 'User' }, thread: { type: ObjectID, required: true, ref: 'Thread' }, parent: { type: ObjectID, required: true, ref: 'Comment' }, text: { type: String, required: true }, }, { timestamps: true, }); Besides a single query via _id , I want to query the database via this way: Range query const query = { thread: req.query.threadID, _id: { $gt: req.query.startFrom } };

问题 I have created a recursive template for getting the first n number of items from my XML. It uses an index(counter) just like how I would in a for loop. Now how can I get a node from my XML using the index? I have tried [position()=$index] but it had weird behaviour when trying to get deeper nodes in the XML hierarchy. If I have XML such as: <0> <1> <2>item</2> <2>item</2> <2>item</2> <2>item</2> <2>item</2> <2>item</2> </1> </0> I want to be able to count through and copy the 2's until I have

问题 We have a table with, say, 5 indices (one clustered). Question: will it somehow negatively affect optimizer performance - either speed or accuracy of index picks - if all 5 indices start with the same exact field? (all other things being equal). It was suggested by someone at the company that it may have detrimental effect on performance, and thus one of the indices needs to have the first two fields switched. I would prefer to avoid change if it is not necessary, since they didn't back up