In a non-replicate scenario (or one where we have one write master only), would the following work as quick way to give a doc an auto-increment id to small internal customer datbase.
On inserting a new customer query http://couhdb/mydb to get the metadata
Then add doc_count + doc_deleted_count = autoIncId
Set a property on the doc as .oldDbCompatIdThatClientIsUsedTo = auotIncId
This would mean serialize/sync the process of getting the db metadata and writting the doc but thats not a problem given 20 customers added a day etc..
I can think of a couple of ways of doing this:
Create a view that returns max(id) and just assign max(id) + 1 to the new item (there's some chance of collision here though)
Store another document in the database that isn't a normal record but just contains the sequence value. When you want to do a new insert fetch the current value from this doc, add one, save it back to the doc and then if none of that failed use that id for the new record
Related
I have created Vehicle Table In the Ledger and added some vehicles in QLDB and I deleted the vehicle data.Now I am not able to fetch the metadata id because user table and committed table will have only non-deleted latest version of application data.So I am not able to fetch History of that deleted Data through metadata.Kindly help me with PartiQL query to fetch the History, if there is a way.
Note: I don't have vehicle registration table which stores metadataId of vehicles.
The way you are doing it is correct. First, you filter on history by some known attribute (in this case, a user defined primary key such as 'VIN') and you retrieve the document id. After that, you can filter history using that document id.
The second query should return the same as the first but it will also contain the deletion information (the first query will not include it because the deletion removes the attribute).
Note that the document id is returned as part of the DELETE PartiQL statement.
I have a single collection into which I am inserting documents of different types. I use the type parameter to distinguish between different datatypes in the collection. When I am inserting a document, I have created an Id field for every document, but Cosmosdb has a built-in id field.
How can I insert a new document and retrieve the id of the created Document all in one query?
The CreateDocumentAsync method returns the created document so you should be able to get the document id.
Document created = await client.CreateDocumentAsync(collectionLink, order);
I think you just need to .getResource() method to get the create document obj.
Please refer to the java code:
DocumentClient documentClient = new DocumentClient(END_POINT,
MASTER_KEY, ConnectionPolicy.GetDefault(),
ConsistencyLevel.Session);
Document document = new Document();
document.set("name","aaa");
document = documentClient.createDocument("dbs/db/colls/coll",document,null,false).getResource();
System.out.println(document.toString());
//then do your business logic with the document.....
C# code:
Parent p = new Parent
{
FamilyName = "Andersen.1",
FirstName = "Andersen",
};
Document doc = client.CreateDocumentAsync("dbs/db/colls/coll",p,null).Result.Resource;
Console.WriteLine(doc);
Hope it helps you.
Sure, you could always fetch the id from creation method response in your favorite API as already shown in other answers. You may have reasons why you want to delegate key-assigning to DocumentDB, but to be frank, I don't see any good ones.
If inserted document would have no id set DocumentDB would generate a GUID for you. There wouldn't be any notable difference compared to simply generating a new GUID yourself and assign it into id-field before save. Self-assigning the identity would let you simplify your code a bit and also let you use the identity not only after persisting but also BEFORE. Which could simplify a lot of scenarios you may have or run into in future.
Also, note that you don't have to use GUIDs as as id and could use any unique value you already have. Since you mentioned you have and Id field (which by name, I assume to be a primary key) then you should consider reusing this instead introducing another set of keys.
Self-assigned non-Guid key is usually a better choice since it can be designed to match your data and application needs better than a GUID. For example, in addition to being just unique, it may also be a natural key, narrower, human-readable, ordered, etc.
We want to check if a document already exists in the database with the same fields and values of a new object we are trying to save to prevent duplicated item.
Note: This question is not about updating documents or about duplicated document IDs, we only check the data to prevent saving a new document with the same data of an existing one.
Preferably we'd like to accomplish this with Mango/Cloudant queries and not rely on views.
The idea so far is:
1) Scan the the data that we are trying to save and dynamically create a selector that matches that document's structure. (We can't have the selectors hardcoded because we have types of many documents)
2) Query de DB with for any documents matching that selector to if any document already exists that matches those criteria.
However I wonder about the performance of this approach since many of the selector fields will not be indexed.
I also much rather follow best practices than create something out of the blue, but haven't been able to find any known solutions for this specific scenario.
If you happen to know of any, please share.
Option 1 - Define a meaningful ID for your documents
The ID could be a logical coposition or a computed hash from the values that should be unique
If you want to check if a document ID already exists you can use the HEAD method
HEAD /db/docId
which returns 200-OK if the docId exits on the database.
If you would like to check if you have the same content in the new document and in the previous one, you may use the Validate Document Update Function which allows to compare both documents.
function(newDoc, oldDoc, userCtx, secObj) {
...
}
Option 2 - Use content hash computed outside CouchDB
Before create or update a document a hash should be computed using the values of the attributes that should be unique.
The hash is included in the document in a new attribute i.e. "key_hash"
Create a mango index using the "key_hash" attribute
When a new doc should be inserted, the hash should be computed and find for documents with the same hash value using a mango expression before the doc is inserted.
Option 3 - Compute hash in a View
Define a view which emit the computed hash for each document as key
Couchdb Javascript support does not include hashing functions, this could be difficult to include in a design document.
Use erlang to define the map function, where you can access to the erlang support for hashing.
Before creating a new document you should query the view using a the hash that you need to compute previously.
One solution would be to take Juanjo's and Alexis's comment one step further.
Select the keys you wish to keep unique
Put the values in a string and generate a hash
Set the document's _id to that hash
PUT the document on the database.
check return for failure
If another document already exists on the database with the same _id value, the PUT request will fail.
Hi I'm facing a task that requires me (or not?) to do some small changes directly on the CRM SQL DB.
Situation:
1) there was a N:1 relation between two entities that was changed to N:N.
2) For each entities I need to move related stuff from previous relation to new one.
For active entities it was no problem cause customer didn't care about changing fields "ModifiedOn", "ModifiedBy" and "ClosedOn" but for inactive (an incident that is closed for example) he'd like to migrate the related entities, but not to change these three fields. Because all those incidents are closed/inactive I cannot just call "AssociateRequest" I need to re-open case, associate, close it again. this of course will change these fields.
Is there any way to do this via the API and not directly on SQL? If not - could it be a problem?
If you already have the mechanism to change the Relationship and just need to modify the records CreatedOn, CreatedBy, ModifiedOn, and ModifiedBy...You should be able to do this using late bound code:
Entity YourTargetEntity= new Entity("YourTargetEntity");
YourTargetEntity["createdon"] = new DateTime(2015,01,01); // or whatever the date you want
YourTargetEntity["overriddencreatedon"] = new DateTime(2015,01,01); // or whatever the date you want
YourTargetEntity["createdby"] = new EntityReference("systemuser", new Guid("XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX"));
TargetEntity["modifiedby"] = new EntityReference("systemuser", new Guid("XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX"));
TargetEntity["modifiedon"] = new DateTime(2015,01,01); // or whatever the date you want
_service.Update(YourTargetEntity);
Hope that helps.
In past with my PHP / Rails - MYSQL apps I've used the unique ID of a table record to keep track of a record in an html file.
So I'd keep track of how to delete a record shown like this (15 being the ID of the record):
Delete this record
So now I'm using MongoDB. I've tried the same method but the objectID ._id attribute seems to be a loooong byte string that I can't use conveniently.
What's the most sensible way of binding a link in the view to a record (for deletion, or other purposes or whatever)?
If the answer is to create a new id that's unique for each document in the collection, then what's the best way to generate those unique id's?
Thank you.
You could use a counter instead of the ObjectID
But this could create a problem when inserting a new document after you deleted a previous one.
See this blog post for more detail info on Sequential unique identifiers with Node.js and MongoDB.
Or you could use the timestamp part of the ObjectID:
objectId.getTimestamp().toString()
See the node objectid docs