db.collection.createIndex()ΒΆ
Creates indexes on collections.
I understand why we need indexes on documents, but why on collections?
Thanks everyone for helping!
We are not creating indexes on documents, we index documents on collections, selecting one or more keys. Like you index columns in tables on relational DB world.
Just to find right document (row) from collection (table).
the index creates a part in the storage where the engine can look for entries. The parsing of these entries is really fast. In my case it gives me a performance benefit of aditionally 1000%.
A Find or Aggregate searches through this storage and can find the wanted data without parsing the whole collection.
Related
I actually want To display Full documents Without duplication
When I use distinct i can only display one particular field
How to display all fields without selecting that document which is repeated
Each document in MongoDB contains an _id field which must be unique in the collection. Hence, it is not possible to have two identical documents in a collection. Ergo, iterating a collection with no conditions will return all unique documents (which are all documents in the collection).
Is there a way to limit azure cognitive search results based on a condition for e.g.:
if content.length < 500:
I have several thousand pdf files indexed and many files are completely useless have less content. I don't want those files to show up in the search response.
I cannot delete them manually as these files are in large number.
Any help would be highly appreciated.
If you're using a blob indexer to populate your search index you can add a new/additional index field and populate it with metadata_storage_size. Be sure that this "size" field is configured as filterable, and you should be able to use that field to filter out small PDFs.
https://learn.microsoft.com/en-us/azure/search/search-howto-indexing-azure-blob-storage#how-azure-cognitive-search-indexes-blobs
If you're populating the data in your search index manually, I think you'll still need a field to hold the document's size, and will need to populate it yourself.
I'm searching a curl command to delete documents filtered with few conditions or other ways to delete specific documents. Is there any way to achieve that?
You can't do that in one query like you would do in SQL.
You have to query the documents with a filter (let's say a Mango Selector). Then, you need to update those documents with the field "_deleted": true to delete it.
Photon admin panel since v1.9.30 allows to select results of viewindex function and treats a selection as a list of documents. Having appropriate index you can select its parent docs and then delete them.
I am trying to find a value in collection using "collection contains value" action in Collection manipulation VBO. I want to read the row index of the value read. Can someone guide me.
There are two methods to completing this:
Loop over your collection and compare the search term to each Collection item. This is computationally expensive (especially for large collections), but it will yield you the right result with minimal development time.
Modify the Collection Manipulation object - Duplicate the pre-existing "Filter Collection" Action from the Utility - Collection Manipulation object, and modify the code stage that leverages the previous calls to DataTable's select and utilizes it against the indexOf functionality to retrieve the index of the row you're searching for (relevant SO link). This is ideal for larger collections and would seem to me to be generally more sustainable long-term.
i need to develop a search application , where many documents are indexed with different fields and a id field which is unique for each of the document . Fields are not stored just indexed except for id field
i need to find out for each document , the documents similar to this, here all i have is unique id field of current document , i dont have any other fields of current document to form Terms and query the index for finding similar documents like current one.
How do i do this ? any help greatly appreciated .
I believe the simplest way to do this is to use Solr, and use Solr's MoreLikeThisHandler.
You can use a query likehttp://localhost:8983/solr/select?q=unique_id:2722&mlt=true&mlt.fl=manu,cat&mlt.mindf=1&mlt.mintf=1&fl=id,score
Do you have any control over how these documents are indexed? You can index with term vectors, and at query time, look up the term vector for the document, construct a query using the terms, and submit the query.