I wanted to create a compound unique index using 2 fields, but one of those has a path to some inner field like evaluated.rut. But I got an error:
I don't get the error, in MongoDB I had created index like that, but I can't now in CosmosDB, any suggestion?
Provided the nested path is not an array, the support for this is coming out very soon using the value EnableUniqueCompoundNestedDocs in the capabilities property array for a Cosmos DB databaseAccounts resource in ARM.
This is not yet publicly available. If you'd like to try today you can open a support ticket and ask this capability be added your Cosmos account. You can also DM me on Twitter (see my SO profile) and send me your Cosmos account name and I can request it for you.
You can refer to this document for what is not supported and its limitations.
Related
I am very new to Azure and currently looking for assistance to help me start my project. Recently I am trying to automate the process of adding alerts for our Azure CosmosDB.
After some research, it looks like I can use Add-AzMetricAlertRuleV2 to add alerts through powershell. According to MS online document I will need to pass $condition to add the rule to the existing ResourceGroup. Where can I get all the existing conditions that I can add to the rule so I can sort out the one that is needed? Some people use New-AzMetricAlertRuleV2Criteria to assign the value that need to be passed to $condition. And I can see some example from MS website: https://learn.microsoft.com/en-us/powershell/module/az.monitor/new-azmetricalertrulev2criteria?view=azps-5.0.0
However the above document from MS is not clear to me where I can find the whole list of the name spaces along with the existing criterias that I can add. For example, if I want to add an alert when a new cosmos DB is created on one of the existing ResourceGroup using powershell, where can I check what is the name space I can use to add the new criteria? In another word, where can I find out all the existing conditions with the name space along with them? Thanks,
For cosmos DB, the metric namespace will be Microsoft.DocumentDB/databaseAccounts.
Is it possible in some way to have multiple access conditions that prevent the document to be saved to cosmos if they isn't met.
Today I have an accesscondition on the ETag, to prevent an old version of the document to be saved. But I want to have another condition based on the status of the document. So if the document in my store is in a 'closed' status, it will prevent any from modifying it.
I can always do a load -> check -> save routine, but the accesscondition works like a charm for the ETag so I wonder if there is a way to have multiple access condition specified when saving the document.
Best Regards
Magnus
Based on the detailed statements in below blogs,
1.https://codeopinion.com/documentdb-optimistic-concurrency/
2.https://chapsas.com/understanding-optimistic-concurrency-in-cosmos-db/
ETAG in cosmos db only provides optimistic concurrency and can be used with an AccessCondition in order to ensure that if the document changed between the retrieval and the manipulation attempt of the document.
AccessConditionType only has IfMatch or IfNoneMatch,no more other status.
So,back to your requirements,it seems that you have to add ifClosed item in your document and check it when you do modification to implement your needs.
I need to query a collection and return all documents that are new or updated since the last query. The collection is partitioned by userId. I am looking for a value that I can use (or create and use) that would help facilitate this query. I considered using _ts:
SELECT * FROM collection WHERE userId=[some-user-id] AND _ts > [some-value]
The problem with _ts is that it is not granular enough and the query could miss updates made in the same second by another client.
In SQL Server I could accomplish this using an IDENTITY column in another table. Let's call the table version. In a transaction I would create a new row in the version table, do the updates to the other table (including updating the version column with the new value. To query for new and updated rows I would use a query like this:
SELECT * FROM table WHERE userId=[some-user-id] and version > [some-value]
How could I do something like this in Cosmos DB? The Change Feed seems like the right option, but without the ability to query the Change Feed, I'm not sure how I would go about this.
In case it matters, the (web/mobile) clients connect to data in Cosmos DB via a web api. I have control of the entire stack - from client to back-end.
As the statements in this link:
Today, you see all operations in the change feed. The functionality
where you can control change feed, for specific operations such as
updates only and not inserts is not yet available. You can add a “soft
marker” on the item for updates and filter based on that when
processing items in the change feed. Currently change feed doesn’t log
deletes. Similar to the previous example, you can add a soft marker on
the items that are being deleted, for example, you can add an
attribute in the item called "deleted" and set it to "true" and set a
TTL on the item, so that it can be automatically deleted. You can read
the change feed for historic items, for example, items that were added
five years ago. If the item is not deleted you can read the change
feed as far as the origin of your container.
Change feed is not available for your requirements.
My idea:
Use Azure Function Cosmos DB Trigger to collect all the operations in your specific cosmos collection. Follow this document to configure the input of azure function as cosmos db, then follow this document to configure the output as azure queue storage.
Get the ids of changed items and send them into queue storage as messages.When you want to query the changed item,just query the messages from the queue to consume them at a specific unit time and after that just clear the entire queue. No items will be missed.
With your approach, you can get added/updated documents and save reference value (_ts and id field) somewhere (like blob)
SELECT * FROM collection WHERE userId=[some-user-id] AND _ts > [some-value] and id !='guid' order by _ts desc
This is a similar approach we use to read data from Eventhub and store checkpointing information (epoch number, sequence number and offset value) in blob. And at a time only one function can take a lease of that blob.
If you go with ChangeFeed, you can create listener (Function or Job) to listen all add/update data from collection and you can store those value in some collection, while saving data you can add Identity/version field on every document. This approach may increase your cosmos DB bill.
This is what the transaction consistency levels are for: https://learn.microsoft.com/en-us/azure/cosmos-db/consistency-levels
Choose strong consistency and your queries will always return the latest write.
Strong: Strong consistency offers a linearizability guarantee. The
reads are guaranteed to return the most recent committed version of an
item. A client never sees an uncommitted or partial write. Users are
always guaranteed to read the latest committed write.
Coming from a mongodb background, I'd like to set up a document with an embedded collection.
For instance if I have a profile object
Profile
name : string
followers : [
name: string
]
such that it has an embedded collection of followers.
Is there a way that I can create an index on Profile so that I can query for all profiles where Profile.Followers includes myUsername?
In short I can query for profiles I'm following from a dynamoDB table?
In mongo I can easily do this by setting up an index on Profile.followers and doing an $in query. Is there something similar for dynamodb?
This documentation suggests there is nothing like an in clause
http://docs.aws.amazon.com/amazondynamodb/latest/developerguide/QueryAndScan.html
Currently DynamoDB does not support indices for non scalar types (i.e. Set, List, or Map data types - see here: http://docs.aws.amazon.com/amazondynamodb/latest/developerguide/SecondaryIndexes.html). If you have a separate users table, you can keep track of all profiles you are following in a Set/List attribute.
Folks, I was wondering what is the best way to model document and/or map functions that allows me "Not Equals" queries.
For example, my documents are:
1. { name : 'George' }
2. { name : 'Carlin' }
I want to trigger a query that returns every documents where name not equals 'John'.
Note: I don't have all possible names before hand. So the parameters in query can be any random text like 'John' in my example.
In short: there is no easy solution.
You have four options:
sending a multi range query
filter the view response with a server-side list function
using a CouchDB plugin
use the mango query language
sending a multi range query
You can request the view with two ranges defined by startkey and endkey. You have to choose the range so, that the key John is not requested.
Unfortunately you have to find the commit request that somewhere exists and compile your CouchDB with it. Its not included in the official source.
filter the view response with a server-side list function
Its not recommended but you can use a list function and ignore the row with the key John in your response. Its like you will do it with a JavaScript array.
using a CouchDB plugin
Create an additional index with e.g. couchdb-lucene. The lucene server has such query capabilities.
use the "mango" query language
Its included in the CouchDB 2.0 developer preview. Not ready for production but will be definitely included in the stable release.