I'm working with mongoDB, and I used a wrapper mongo/Postegres.
Now, I can find my tables and data.
I want to do some statistics but I can't reach objects that got json type in Postgres.
My problem is that I got all the object in json but I need to separate the fields.
I used this :
CREATE FOREIGN TABLE rents( _id NAME, status text, "from" json )
SERVER mongo_server
OPTIONS (database 'tr', collection 'rents');
The field "from" is an object.
I found something like this :
enter code here
but nothing happened
The error (why a screenshot??) means that the data are not in valid json format.
As a first step, you could define the column as type text instead of json. Then querying the foreign table will probably work, and you can see what is actually returned and why PostgreSQL thinks that this is not valid JSON.
Maybe you can create a view on top of the foreign table that converts the value to valid JSON for further processing.
Related
I have a table in AWS Glue, and the crawler has defined one field as array.
The content is in S3 files that have a json format.
The table is TableA, and the field is members.
There are a lot of other fields such as strings, booleans, doubles, and even structs.
I am able to query them all using a simpel query such as:
SELECT
content.my_boolean,
content.my_string,
content.my_struct.value
FROM schema.tableA;
The issue is when I add content.members into the query.
The error I get is: [Amazon](500310) Invalid operation: schema "content" does not exist.
Content exists because i am able to select other fiels from the main key in the json (content).
Probably is something related with how to perform the query agains array field in Spectrum.
Any idea?
You have to rename the table to extract the fields from the external schema:
SELECT
a.content.my_boolean,
a.content.my_string,
a.content.my_struct.value
FROM schema.tableA a;
I had the same issue on my data, I really don't know why it needs this cast but it works. If you need to access elements of an array you have to explod it like:
SELECT member.<your-field>,
FROM schema.tableA a, a.content.members as member;
Reference
You need to create a Glue Classifier.
Select JSON as Classifier type
and for the JSON Path input the following:
$[*]
then run your crawler. It will infer your schema and populate your table with the correct fields instead of just one big array. Not sure if this was what you were looking for but figured I'd drop this here just in case others had the same problem I had.
I am asked to enter a stringified json value in a column named show_cast in the format of Release: and Date: but I don't have any idea how to do that.
The table simply contains of three columns a token , time and genre. The time has to be a stringified json.
I tried to simply put that using { and simple : but that doesn't seem to work. They say that {{release:,time:},{release:,date:},,,,} should be converted in stringify and then inserted into the database. I don't know how to do that and I don't see any resource like this out there. To be honest I didn't even know about this until I was given this task.
insert into show_reality values("project_123","{{release:2017,date:04-11},{release:2019,date:12-03}}","Action");
I have done this but I don't think it is a stringified json.
Thanks in Advance.
I'm trying to insert JSON into a Postgresql column who's data type is JSON, but I'm having trouble finding how I can do this. This is as far as I've gotten but it's not correct because it just overwrites it every time, instead of adding a new key pair.
I'm using pg-promise node module to perform these queries. Here's what I have so far:
db.query("UPDATE meditation_database SET completed=$1 WHERE user_id=$2", [{myVar : true}, user_id]);
Also 'myVar' should be updated to the variable value, but instead it treats it as a string. How can I get the actual value of 'myVar' instead of it being treated literally.
Thanks,
I'm trying to insert JSON into a Postgresql column who's data type is JSON, but I'm having trouble finding how I can do this.
By executing this:
db.query("INSERT INTO meditation_database(completed, user_id) VALUES($1, $2)",
[{myVar : true}, user_id]);
Also 'myVar' should be updated to the variable value, but instead it treats it as a string. How can I get the actual value of 'myVar' instead of it being treated literally.
myVar is serialized into JSON as a string, that's the proper JSON format for property names, and is the only format that PostgreSQL will accept.
This is as far as I've gotten but it's not correct because it just overwrites it every time, instead of adding a new key pair.
If you are asking how to update JSON in PostgreSQL, this question has been answered previously, and in great detail: How do I modify fields inside the new PostgreSQL JSON datatype?
I downloaded solr 4.6.1 and I am attempting to update the solr index using the following via command line:
curl http://localhost:8983/solr/update?commit=true -H 'Content-type:application/json' -d '
[{
"id" : "1",
"phoneNumber_ss": [{"foo_ss" : "bar"}]
}]
'
I am using the example schema.xml, which is why i used all the "_ss" fields.
The issue is that when I execute this I get the following response:
{"responseHeader":{"status":400,"QTime":1},"error":{"msg":"Error parsing JSON field value. Unexpected OBJECT_START","code":400}}
This seems to be related to the value specified for phoneNumber_ss field which is an array of objects. If I make the value into an array or an object it works fine, its only when it is an array of objects that the issue occurs.
Any help is much appreciated.
I don't think Solr support storing objects into a multivalued field. You can store it as a array of string. You might also store the object as a string and parse it in your application.
If you have such use case that you want to have all the objects from Solr only, you can follow the steps..
Create a multivalued field for your keys.
Maintain the same order of keys and create another multivalued field for values.
So, you can get the keys and values in same order in different fields. But in this approach you might face problems while updating those multivalued fields. You might want to look here
And finally, you are also missing some syntax in your update statement.
set – set or replace a particular value, or remove the value if null is specified as the new value
add – adds an additional value to a list
Check http://wiki.apache.org/solr/UpdateJSON
Say I have a text field with JSON data like this:
{
"id": {
"name": "value",
"votes": 0
}
}
Is there a way to write a query which would find id and then would increment votes value?
I know i could just retrieve the JSON data update what I need and reinsert updated version, but i wonder is there a way to do this without running two queries?
UPDATE `sometable`
SET `somefield` = JSON_REPLACE(`somefield`, '$.id.votes', JSON_EXTRACT(`somefield` , '$.id.votes')+1)
WHERE ...
Edit
As of MySQL 5.7.8, MySQL supports a native JSON data type that enables efficient access to data in JSON documents.
JSON_EXTRACT will allow you to access a particular JSON element in a JSON field, while JSON_REPLACE will allow you to update it.
To specify the JSON element you wish to access, use a string with the format
'$.[top element].[sub element].[...]'
So in your case, to access id.votes, use the string '$.id.votes'.
The SQL code above demonstrates putting all this together to increment the value of a JSON field by 1.
I think for a task like this you're stuck using a plain old SELECT followed by an UPDATE (after you parse the JSON, increment the value you want, and then serialize the JSON back).
You should wrap these operations in a single transaction, and if you're using InnoDB then you might also consider using SELECT ... FOR UPDATE : http://dev.mysql.com/doc/refman/5.0/en/innodb-locking-reads.html
This is sort of a tangent, but I thought I'd also mention that this is the type of operation that a NoSQL database like MongoDB is quite good at.