I have created a data type called id which consists of two text values:
id(text, text)
I now need to cast values to this data type before they are inserted into my table. How would I go about doing this?
I created the type as follows:
CREATE TYPE ID AS(id text, source text);
Well, to create a cast you need a function that takes a value of one type as your input and outputs the type you wish to cast to (in this case "ID" - which I would name a little more verbose if I were you). What type do you want to cast from?
Realize without messing with all that, you should be able to use your type according to this page.
Just..
SELECT ROW('foo','bar')::ID ;
You have to tell PostgreSQL how to cast, CREATE CAST
if we are talking about "user defined types" which are realy compatible with each other, so you can cast the type to text first and then to your custom type admin_action::text::"UserAction"
in my case "admin_action" was of type "AdminAction" and couldn't be converted to "UserAction" directly, but I've done it through "text" step.
Related
I use user defined type like
create type type_name table of (varchar2(32000));
In oracle and to extend the size of that type i used extend method of collection
type_name.extend();
but now i am converting the oracle database to postgresql and i m using user defined type and i want to extend the size of that type so which method i used to extend the size of that type in postgresql.
I try various method like unnest and append but they are not working please tell me alternative of extend method...
When I tried to get some values in a DataFrame, like:
df.select("date").head().get(0) // type: Any
The result type is Any, which is not expected.
Since a dataframe contains the schema of the data, it should know the DataType for each column, so when i try to get a value using get(0), it should return the value with the correct type. However, it does not.
Instead, I need to specify which DataType i want using getDate(0), which seems weird, inconvenient, and makes me mad.
When I have specified the schema with the correct DataTypes for each column when i created the Dataframe, I don't want to use different getXXX()' for differentcolumn`s.
Are there some convenient ways that I can get the values with their own correct types? That is to say, how can I get the values with the correct DataType specified in the schema?
Thank you!
Scala is a statically typed language. so the get method defined on the Row can only return values with a single type because the return type of the get method is Any. It cannot return Int for one call and a String for another.
you should be calling the getInt, getDate and other get methods provided for each type. Or the getAs method in which you can pass the type as a parameter (for example row.getAs[Int](0)).
As mentioned in the comments other options are
use Dataset instead of a DataFrame.
use Spark SQL
You can call the generic getAs method as getAs[Int](columnIndex), getAs[String](columnIndex) or use specific methods like getInt(columnIndex), getString(columnIndex).
Link to the Scaladoc for org.apache.spark.sql.Row.
I'm using OrientDB and trying to create new property after I inserted my data (millions of rows).
I'm trying to create property on V in order to create an index and I'm getting the following error:
The database contains some schema-less data in the property
'V.ACCOUNT_NO' that is not compatible with the type STRING. Fix those
records and change the schema again [ONetworkProtocolHttpDb]
Now part of the fields type is INTEGER but it seems to me that it's very easy to convert the type to STRING.
how can I do it to the entire data?
I tried your case by creating this simple structure in schema-less mode:
These records are a mix of INTEGER and STRING types:
Now you can convert the not string records type by using this query:
UPDATE V SET ACCOUNT_NO = ACCOUNT_NO.asString() WHERE ACCOUNT_NO.type() <> 'STRING'
Output:
About the exception, I got correctly the same error when I try to create a new property V.ACCOUNT_NO of type STRING in schema-full mode and this is correct because the property already exists in the database and contains mixed types of records, although in schema-less mode.
Once all the records were converted, you'll able to create the new property.
Hope it helps
As title shown, when reading the manul, I found type record type and row type, which are both composite type. However, I want to figure out their difference.
They're similar once defined but tend to have different use cases.
A RECORD type has no predefined structure and is typically used when the row type might change or is out of your control, for example if you're referencing a record in a FOR LOOP.
ROWTYPE is predefined of a particular table row structure and thus if anything deviates from that structure you will get runtime errors.
It all depends what you're trying to achieve.
For cursor loops I use a RECORD>
For more information:
http://www.postgresql.org/docs/current/static/plpgsql-declarations.html
Is it possible to use the %TYPE and array together?
CREATE FUNCTION role_update(
IN id "role".role_id % TYPE,
IN name "role".role_name % TYPE,
IN user_id_list "user".user_id % TYPE[],
IN permission_id_list INT[]
)
I got syntax error by this, but I don't want to duplicate any column type, so I want to use "user".user_id % TYPE instead of simply INT because then it is easier to modify any column type later.
As the manual explains here:
The type of a column is referenced by writing table_name.column_name%TYPE. Using this feature can sometimes help make a function independent of changes to the definition of a table.
The same functionality can be used in the RETURNS clause.
But there is no simple way to derive an array type from a referenced column, at least none that I would know of.
About modifying any column type later:
You are aware that this type of syntax is only a syntactical convenience to derive the type from a table column? Once created, there is no link whatsoever to the table or column involved.
It helps to keep a whole create script in sync. But id doesn't help with later changes to live objects in the database.
Related answer on dba.SE:
Array of template type in PL/pgSQL function using %TYPE
Using referenced types in function's parameters has no sense (in PostgreSQL), because its translated intermediately to actual types, and it is stored as actual types. Sorry, PostgreSQL doesn't support this functionality - something different is using referenced types inside function, where actual type is detected every first time execution in session.