indexing

问题 I use Mango queries with Couchdb when users want to search the database. They can search by multiple fields in the document. To simplify I have a document with three fields all of which can be searched to find the document. FieldOne: cow FieldTwo: pig FieldThree: dog When creating a mango index for the query what fields should I use? Should I create and index with multiple fields? Does the order matter? There are also three different document types (A, B C) defined in a field. I only need to

问题 I have typed this command to index a document in Elasticsearch create an index curl -X PUT "localhost:9200/test_idx_1x" create a mapping curl -X PUT "localhost:9200/test_idx_1x/test_mapping_1x/_mapping" -d '{ "test_mapping_1x": { "properties": { "my_attachments": { "type": "attachment" } } } }' index this document curl -XPUT 'http://localhost:9200/test_idx_1x/test_mapping_1x/4' -d '{ "post_date": "2009-11-15T14:12:12", "message": "test Elastic Search", "name": "N1" }' All these three commands

问题 I am working on an application using Spring Data MongoDB. I would like to create a compound index on one of my models. I have added a @CompoundIndex annotation at the top like so: @Document @CompoundIndexes({ @CompoundIndex(name = "name_", def = "{ 'tenantId': 1, 'name': 1 }", unique = true) }) public class MyModel { } However, the index is not created. I have also tried to directly place the @CompoundIndex above the class. The collection is still missing the index. The same index definition

问题 I am working on an application using Spring Data MongoDB. I would like to create a compound index on one of my models. I have added a @CompoundIndex annotation at the top like so: @Document @CompoundIndexes({ @CompoundIndex(name = "name_", def = "{ 'tenantId': 1, 'name': 1 }", unique = true) }) public class MyModel { } However, the index is not created. I have also tried to directly place the @CompoundIndex above the class. The collection is still missing the index. The same index definition

问题 We have a table with more than two million rows where all queries against it will be a Between lookup using Column1 and Column2 . Also, there will only be one possible result. For example... Col1 Col2 1 5 6 10 11 15 select * from table1 where 8 between Col1 and Col2 I currently have an unique clustered index on Col1 and Col2 . So far I have been unable to figure out how to further tune the query and the indexes to minimize the rows handled. The execution plan currently reports cost of almost

问题 For example, I have three lists (of the same length) A = [1,2,3] B = [a,b,c] C = [x,y,z] and i want to merge it into something like: [[1,a,x],[2,b,y],[3,c,z]]. Here is what I have so far: define merger(A,B,C): answer = for y in range (len(A)): a = A[y] b = B[y] c = C[y] temp = [a,b,c] answer = answer.extend(temp) return answer Received error: 'NoneType' object has no attribute 'extend' 回答1: It looks like your code is meant to say answer = [] , and leaving that out will cause problems. But the

问题 I have a high-demand transactional database that I think is over-indexed. Originally, it didn't have any indexes at all, so adding some for common processes made a huge difference. However, over time, we've created indexes to speed up individual queries, and some of the most popular tables have 10-15 different indexes on them, and in some cases, the indexes are only slightly different from each other, or are the same columns in a different order. Is there a straightforward way to watch

问题 I have a 4 dimensional array, i.e., data.shape = (20,30,33,288) . I am finding the index of the closest array to n using index = abs(data - n).argmin(axis = 1), so index.shape = (20,33,288) with the indices varying. I would like to use data[index] = "values" with values.shape = (20,33,288) , but data[index] returns the error "index (8) out of range (0<=index<1) in dimension 0" or this operation takes a relatively long time to compute and returns a matrix with a shape that doesn't seem to make

问题 I have a query like this: SELECT fields FROM table WHERE field1='something' OR field2='something' OR field3='something' OR field4='something' What would be the correct way to index such a table for this query? A query like this takes a entire second to run! I have 1 index with all 4 of those fields in it, so I'd think mysql would do something like this: Go through each row in the index thinking this: Is field1 something? How about field2? field3? field4? Ok, nope, go to the next row. 回答1: You

问题 Could I write (with IndexWriter ) new documents into index while it is opened for reading (with IndexReader )? Or must I close reading before writing? Could I read/search documents (with IndexReader ) in index while it is opened for writing (with IndexWriter )? Or must I close writing before reading? Is Lucene.Net thread safely or not? Or must I write my own? 回答1: You may have any amount of readers/searchers opened at any time, but only one writer. This is enforced by a directory specific