I am new to AWS Web Services and am interested in DynamoDB. What is DynamoDB's item?
Is it column or a row or a field? Any related suggestions are welcome.
Consider items as a row. There are various methods like:
getItem - it will get a single row
BatchPutItems - it will insert multiple rows
etc.
There are other manipulations as well, which you can refer to here.
Related
I'm using cosmosdb with azure table api and no where can I see any way to get total records count from a table. Can see that there are ways to get count of records with sql api. What is the best possible way to get count using azure table apis? I'm using nodejs to connect to this instance.
What is the best possible way to get count using azure table apis?
Based on my researching and rest api, unfortunately, there is no directly way to get count using azure table api which is similar to count keyword in sql api query.
One way to do so would be to list all entities in a table and get their count. This is an utterly horrid approach and can be a bit costly if you have to iterate through billions of records. Best you can do is do a projected query to enumerate through all the Partition & Row keys and sum them up thus controlling the cost and time of the operation.
In addition,you could send your desired requirement in cosmos db feedback.
I found this page: https://microsoft.github.io/AzureTipsAndTricks/blog/tip152.html
I tried to do the same in nodejs and it worked for me:
await container.items.query('SELECT VALUE COUNT(1) FROM c', {maxItemCount: -1}).fetchAll();
we are evaluating if Azure Data Catalog will meet our needs and one of our questions is if we can search for Datasets based on column tags. For example, if some of my datasets have the column tag "xyz" for one of their columns, can I search for all datasets with a column tag "xyz" and get all the datasets that have a column (any column) with the tag "xyz"?
Also, can this be done programmatically through the REST APIs? Thanks!
Last I checked you can tag individual columns and you can search on those tags. And REST based search API supports an explicit tag search syntax.
The search at AzureDataCatalog.com will include column tags, column names, and object tags etc. If you implement the high tier options, you can roll up tags into business glosseries. For example the business might use "external supplier" but common alternative's used around the business might be 'panel vender' or 'agency' but really they all mean the same thing.
The full search syntax reference can be found here : https://learn.microsoft.com/en-us/rest/api/datacatalog/data-catalog-search-syntax-reference
Basically, I need to field merge a field in a certain table. Let's say TableA.Col1.
The syntax ${TableA.Col1} works perfectly. However, it only shows the first row of data in the table, whereas, I need to field merge the second row of the data as well.
Any suggestions?
I am trying like an array call ${TableA.Col1[0]} or ${TableA.Col1[1]} but no luck.
Hope to meet some Responsys guru here.
Thank you!
You need to use the <#data> directive to pull multiple records from a supplemental table. Interpolations with Table.Column syntax are designed for 1->1 relationships so will only pull the 1st record.
How we can do CRUD operations on complex data models in Cassandra?
I have a project using NOSQL.
I have a column family for my customers.
The column family has just "id" at first.
Then it will be updated by altering new columns.
Count and type of columns for each customer could be different.
Also, each column can include sub columns with ids again and it would be altered, too. So, they should be indexed. And documents are not useful for this issue.
I've read about NOSQL, and I've decided to use Cassandra. I will be thankful if you would answer this questions:
Is the above that possible?
How we can create and use CRUD operations on this column family?
If the answer of last question is true, what is the type of result of a query?
It will return some rows for each primary key (id)?
How we can manage that, to access a table like with no redundancy? because I don't now this summarizing should be manage in DBside or in code side.
Thank you for your help.
RangeSliceQuery has a convenient method to extract only the keys - setReturnKeysOnly() but I couldn't find something similar in SliceQuery (like setReturnColumnNamesOnly()).
Is this functionality provided somewhere in Hector API?
If you want get only column names belonging to a particular column family, i can show you a way how you can achieve it using cql
select * from system.schema_columns WHERE keyspace_name='#KS' AND columnfamily_name='#CF' allow filtering;
Now i don't think it will be great technical hurdle to achieve the same thing using your hector api.
Cheers