data-modeling

Recently I moved my data model from Firebase to Firestore. All my code is working, but I'm having some ugly troubles regarding my nested queries for retrieve some data. Here is the point: Right now my data model for this part looks like this(Yes! Another followers/feed example): { "Users": { //Collection "UserId1" : { //Document "Feed" : { //Subcollection of Id of posts from users this user Follow "PostId1" : { //Document "timeStamp" : "SomeDate" }, "PostId2" : { "timeStamp" : "SomeDate" }, "PostId3" : { "timeStamp" : "SomeDate" } } //Some data } }, "Posts":{ //Collection "PostId1":{ /

Reading several papers and documents on internet, I found many contradictory information about the Cassandra data model. There are many which identify it as a column oriented database, other as a row-oriented and then who define it as a hybrid way of both. According to what I know about how Cassandra stores file, it uses the *-Index.db file to access at the right position of the *-Data.db file where it is stored the bloom filter, column index and then the columns of the required row. In my opinion, this is strictly row-oriented. Is there something I'm missing? Yes, the "column-oriented"

I have a Data model like below, CREATE TABLE appstat.nodedata ( nodeip text, timestamp timestamp, flashmode text, physicalusage int, readbw int, readiops int, totalcapacity int, writebw int, writeiops int, writelatency int, PRIMARY KEY (nodeip, timestamp) ) WITH CLUSTERING ORDER BY (timestamp DESC) where, nodeip - primary key and timestamp - clustering key (Sorted by descinding oder to get the latest), Sample data in this table, SELECT * from nodedata WHERE nodeip = '172.30.56.60' LIMIT 2; nodeip | timestamp | flashmode | physicalusage | readbw | readiops | totalcapacity | writebw | writeiops

I want to enable something like a one-to-many relation between a text object and blobs so that a text object (an "article" or likewise) has many images and/or videos. There are two ways I see how to do this where the first is using a list of blobs as instance variable. Will it work? class A(search.SearchableModel): blobs = db.ListProperty(blobstore.BlobReferenceProperty()) Advantages: Just one class. Readable and easy to get and set data. Disadvantages: Lacks extra info for blobs e.g. if I want to tag a blob with descriptive words I still need two classes instead: class A(search

How would I map something like this using the modelBuilder? Where theres a nullable foreign key referencing the same tables primary key Table: Task taskID int pk taskName varchar parentTaskID int (nullable) FK Task class: public class Task { public int taskID {get;set;} public string taskName {get;set;} public int parentTaskID {get;set;} public Task parentTask {get;set;} } ... modelBuilder.Entity<Task>() .HasOptional(o => o.ParentTask).... The following code gives you the desired schema. Note that you also need to define ParentTaskID foreign key as a nullable integer, like I did below. public

I am working on an app right now which has the potential to grow quite large. The whole application runs through a single domain, with customers being given sub-domains, which means that it all, of course, runs through a common code-base. What I am struggling with is the database design. I am not sure if it would be better to have a column in each table specifying the customer id, or to create a new set of tables (in the same database), or to create a complete new database per customer. The nice thing about a "flag" in the database specifying the customer id is that everything is in a single

I have four tables create table entities{ integer id; string name; } create table users{ integer id;//fk to entities string email; } create table groups{ integer id;//fk to entities } create table group_members{ integer group_id; //fk to group integer entity_id;//fk to entity } I want to make a query that returns all groups where a user belongs, directly or indirectly. The obvious solution is to make a recursion at the application level. I’m wondering what changes can I make to my data model to decrease the database access and as a result have a better performance. In Oracle : SELECT group_id