I want to get all object with available property "available"
For u in col
filter u.available!= null
return u
But the above query would not use index even if u.available is indexed. How can I iterate with the use of index?
With comment from #mpoeter , I can create an index that are specifically spare to force arango to use index.
Related
From the MongoDB documentation they have stated six index types :
Single Field Index
Compound Index
Multikey index
Geospacial index
Text index
Hashed index
The documentation has also stated four index properties.
Unique Indexes
Partial indexes
Sparse Indexes
TTL Indexes
My questions are:
Can any index type have any index property?
Can an index type have more than one index property?
According to the docs: MongoDB creates a unique index on the _id field during the creation of
a collection. Does this mean when I search by Id MongoDB does not do a collection scan but instead uses the id index to execute the query efficiently? Or is the default id index just for uniqueness only? Does a unique index property always support faster queries?
I am using MongoDB via mongoose. When defining a schema in node.js does the field unique: true imply indexing of that will result to efficient search as opposed to a collection scan?
Can materialized views be indexed in MongoDB? If so how?
In the MongoDB documentation it states that MongoDB provides a number of different index types to support specific types of data and queries. Gut there is no explanation of what index properties are. How would you define index properties?
Can any index type have any index property?
Can an index type have more than one index property?
You can test yourself and find out.
Does this mean when I search by Id MongoDB does not do a collection scan but instead uses the id index to execute the query efficiently?
Yes.
Does a unique index property always support faster queries?
Uniqueness refers to a restriction on data which can be placed in the field which is indexed. Both unique and non-unique indexes allow fast retrieval of data queried by indexed fields.
Can materialized views be indexed in MongoDB?
If you are talking about https://docs.mongodb.com/manual/core/materialized-views/, "materialized views" in MongoDB are orthogonal to indexes. You can add indexes on what this page refers to as "output collection" (the argument to $merge) if you wish to query the "materialized view" efficiently.
MongoDB provides a number of different index types to support specific types of data and queries.
Geospatial index supports geo queries. Text index supports text search. Other indexes are general-purpose.
In the cosmos db I have array element "X" and it's mapped to in the index field "X" Collection(Edm.string). If I update X to null then changes does not reflect in the Azure search. Indexer picks up the timestamp change but actual value does not show up in the index. (but if you assign any value, it's show up in the index). Basically when you make your element null, index does not show "null" instead it shows old value.
Any idea how i can fix this?
Set the field to an empty array.
Setting a fields value to null removes it from the index (in contrast to setting it to an empty string or 0).
Collections are, well, collections of values. You can remove values from the collection, but not the collection itself.
I am trying to compare two fields (say lastnames), the result should be populated on the go with other fields when I query. So can I have an option to create such custom field in solr which compares the fields and give the results when queried ?
This seems a use case for Function Values[1] .
Just explore the available function queries[2], select the one which is the best fit for you and use it as the value of a pseudo field.
[1] https://lucene.apache.org/solr/guide/6_6/common-query-parameters.html#CommonQueryParameters-FunctionValues
[2] https://lucene.apache.org/solr/guide/6_6/function-queries.html#FunctionQueries-AvailableFunctions
Suppose I search for a query in Field A, and I want to retrive the corresponding fields B and C from my index, how should I go about it? I am using Lucene 3.6.0.
The results of your query will be returned as a set of documents, not fields. Once you've got a document, you can load whichever field contents you're interested in.
One thing that's probably worth watching out for is to ensure that your fields have been "stored".
Good luck,
How would I set up an index based on lower case only?
Even though the actual field contains both upper and lower case letters.
Also, can I run a query and have only the lower case index value returned?
You can create the index and transform the field to upper- or lower-case. Then when you do your queries, you can do the same transform and it'll do the right thing.
So:
CREATE UNIQUE INDEX lower_case_username ON users ((lower(username)));
Then query for the same thing:
SELECT username FROM users WHERE lower(username) = 'bob';
According to the docs you can do this:
CREATE UNIQUE INDEX lower_title_idx ON films ((lower(title)));
You can also use this for wildcard searches:
CREATE INDEX IF NOT EXISTS foo_table_bar_field ON foo_table(lower(username))
Query like so:
SELECT * FROM foo_table WHERE lower(username) like 'bob%'
CREATE UNIQUE INDEX my_index_name ON my_table (LOWER(my_field));