indexing

问题 I am working on Sitecore 7.2 and using Lucene search, I have created few templates and pages and search is working fine, now I want to exclude few templates from the index, I have a custom crawler and that does remove the templates from indexes but index is not refreshed, I am using following code to update index foreach (Cache cache in CacheManager.GetAllCaches()) { //WriteLog(string.Concat(" Clearing Cache, name = ", cache.Name)); cache.Clear(); } //WriteLog("Clearing caching finished");

问题 I have a array 'x' with four columns. For each row if the 4th column has a value of 1 then I want to delete that entire row: x = np.array([[1,2,3,0],[11,2,3,24],[1,22,3,1],[1,22,3,1], [5,6,7,8], [9,10,11,1]]) for i in range(0,len(x)): if x[i][4]==0: x=np.delete(x, i,0) I get the following error: Traceback (most recent call last): File "", line 2, in if x[i][4]==0: IndexError: index out of bounds 回答1: You can use indexing: >>> x[x[:,3] != 1] array([[ 1, 2, 3, 0], [11, 2, 3, 24], [ 5, 6, 7, 8]]

问题 The documentation for indexing has few examples of assignment of a non-scalar right hand side. In this case, I want to modify a subset of my dataframe, and what I did prior to v.13 no longer works. import pandas as pd from numpy import * data = {'me':list('rttti'),'foo': list('aaade'), 'bar': arange(5)*1.34+2, 'bar2': arange(5)*-.34+2} df = pd.DataFrame(data).set_index('me') print df df.loc['r',['bar','bar2']]*=2.0 print df df.loc['t','bar']*=2.5 # Above fails: ValueError: Must have equal len

问题 I have a compound _id containing 3 numeric properties: _id": { "KeyA": 0, "KeyB": 0, "KeyC": 0 } The database in question has 2 million identical values for KeyA and clusters of 500k identical values for KeyB. My understanding is that I can efficiently query for KeyA and KeyB using the command: find( { "_id.KeyA" : 1, "_id.KeyB": 3 } ).limit(100) When I explain this query the result is: "cursor" : "BasicCursor", "nscanned" : 1000100, "nscannedObjects" : 1000100, "n" : 100, "millis" : 1592,

问题 Say I have the dataset from the example here: import pandas as pd raw_data = {'regiment': ['Nighthawks', 'Nighthawks', 'Nighthawks', 'Nighthawks', 'Dragoons', 'Dragoons', 'Dragoons', 'Dragoons', 'Scouts', 'Scouts', 'Scouts', 'Scouts'], 'company': ['1st', '1st', '2nd', '2nd', '1st', '1st', '2nd', '2nd','1st', '1st', '2nd', '2nd'], 'name': ['Miller', 'Jacobson', 'Ali', 'Milner', 'Cooze', 'Jacon', 'Ryaner', 'Sone', 'Sloan', 'Piger', 'Riani', 'Ali'], 'preTestScore': [4, 24, 31, 2, 3, 4, 24, 31, 2

问题 select * from myTable where myInt will not show any possible_keys when explaining the query even though there is an index on myInt field. Edit: The index in question is not unique. 回答1: For MySQL to use the index, you have to explicitly compare the int field to a value (e.g. true, 1). select * from myTable where myInt = true 回答2: I'm not a database expert, but doesn't it defeat the purpose of having an index on the field if there is only two possible values of the field? If all of the fields

问题 select * from myTable where myInt will not show any possible_keys when explaining the query even though there is an index on myInt field. Edit: The index in question is not unique. 回答1: For MySQL to use the index, you have to explicitly compare the int field to a value (e.g. true, 1). select * from myTable where myInt = true 回答2: I'm not a database expert, but doesn't it defeat the purpose of having an index on the field if there is only two possible values of the field? If all of the fields

问题 After building an index, I'd like to view the contents of the index. Taking an example for illustration from the MonboDB docs: { "_id" : ObjectId("..."), "name" : "Warm Weather", "author" : "Steve", "tags" : [ "weather", "hot", "record", "april" ] } Then an index on the tags field would have these values: { tags: "weather" } { tags: "hot" } { tags: "record" } { tags: "april" } So, I want to run a command, say, db.weather._tags_.find() to display said values. Question: Does such a shell

问题 I have some problems with very slow distinct commands that use a query. From what I have observed the distinct command only makes use of an index if you do not specify a query : I have created a test database on my MongoDB 3.0.10 server with 1Mio objects. Each object looks as follows: { "_id" : ObjectId("56e7fb5303858265f53c0ea1"), "field1" : "field1_6", "field2" : "field2_10", "field3" : "field3_29", "field4" : "field4_64" } The numbers at the end of the field values are random 0-99. On the

问题 i have a table on SQL Server with about 1 million rows. It has an ID (PK), a status (int) and a datetime column. Also I've created an Index on the datetime column. Now I've found out an effect, which I don't understand. SELECT status FROM table WHERE dateTime BETWEEN '2010-01-01T00:00:00' AND '2010-01-02T12:00:00' This statement returns 3664 rows. It runs about 150ms and the execution plan shows that its doing an index seek with key lookup. Now, if I change it as following (just change the