I have created simple entity with Hibernate with #Lob String field. Everything works fine in Java, however I am not able to check the values directly in DB with psql or pgAdmin.
Here is the definition from DB:
=> \d+ user_feedback
Table "public.user_feedback"
Column | Type | Modifiers | Storage | Stats target | Description
--------+--------+-----------+----------+--------------+-------------
id | bigint | not null | plain | |
body | text | | extended | |
Indexes:
"user_feedback_pkey" PRIMARY KEY, btree (id)
Has OIDs: no
And here is that I get from select:
=> select * from user_feedback;
id | body
----+-------
34 | 16512
35 | 16513
36 | 16514
(3 rows)
The actual "body" content is for all rows "normal" text, definitely not these numbers.
How to retrieve actual value of body column from psql?
This will store the content of LOB 16512 in file out.txt :
\lo_export 16512 out.txt
Although using #Lob is usually not recommended here (database backup issues ...). See store-strings-of-arbitrary-length-in-postgresql for alternatives.
Hibernate is storing the values as out-of-line objects in the pg_largeobject table, and storing the Object ID for the pg_largeobject entry in your table. See PostgreSQL manual - large objects.
It sounds like you expected inline byte array (bytea) storage instead. If so, you may want to map a byte[] field without a #Lob annotation, rather than a #Lob String. Note that this change will not be backward compatible - you'll have to export your data from the database then drop the table and re-create it with Hibernate's new definition.
The selection of how to map your data is made by Hibernate, not PostgreSQL.
See related:
proper hibernate annotation for byte[]
How to store image into postgres database using hibernate
Related
I am using Microsoft SQL Server with already stored data.
In one of my tables I can find data like:
+--------+------------+
| id | value |
+--------+------------+
| 1 | 12-34 |
| 2 | 5678 |
| 3 | 1-23-4 |
+--------+------------+
I realized that the VALUE column was not properly formatted when inserted.
What I am trying to achieve is to get id by given value:
SELECT d.id FROM data d WHERE d.value = '1234';
Is there any way to format data in column just before SELECT clause?
Should I create new view and modify column in that view or maybe use complicated REGEX to get only digits (with LIKE comparator)?
P.S. I manage database in Jakarta EE project using Hibernate.
P.S.2. I am not able to modify stored data.
One method is to use replace() before the comparison:
WHERE REPLACE(d.value, '-', '') = '1234'
I need to design a Table in Oracle/SQL & data will be upload via Java/C# application via CSV with 50 fields (mapped to columns of Table). How to design Table/DB with below constraints during data importing from CSV
CSV may have new fields being added to existing 50 fields.
In that case instead of adding column to table manually & load data. How can we design table for smooth/automatic file handling with dynamic fields
EX:
CSV has S_ID, S_NAME, SUBJECT, MARK_VALUE fields in it
+------+---------+-------------+------------+
| S_ID | S_NAME | SUBJECT | MARK_VALUE |
+------+---------+-------------+------------+
| 1 | Stud | SUB_1 | 50 |
| 2 | Stud | SUB_2 | 60 |
| 3 | Stud | SUB_3 | 70 |
+------+---------+-------------+------------+
What if CSV has new field "RANK" (similar more fields) added to it & i need to store all new fields in Table.
Please suggest DB design for this consideration
So there are few approaches come to my mind, one of the way would be having metadata(Record) information in one table (column name, data type, any constraint) and have another free form table with large enough no. of columns which will hold the data. Use the metadata table while inserting data into this table to maintain data integrity and other stuff.
Suppose I have the following tables, in an Oracle DB
Foo:
+--------+---------+---------+
| id_foo | string1 | string2 |
+--------+---------+---------+
| 1 | foo | bar |
| 2 | baz | bat |
+--------+---------+---------+
Bar:
+--------+-----------+--------+
| id_bar | id_foo_fk | string |
+--------+-----------+--------+
| 1 | 1 | boo |
| 2 | 1 | bum |
+--------+-----------+--------+
When I insert into Foo, by using a Dataset and JDBC, such as
Dataset<Row> fooDataset = //Dataset is initialized
fooDataset.write().mode(SaveMode.Append).jdbc(url, table, properties)
an ID is auto-generated by the database. Now when I need to save Bar, using the same strategy, I want to be able to link it to Foo, via id_foo_fk.
I looked into some possibilities, such as using monotonically_increasing_id() as suggested in this question, but it won't solve the issue, as I need the ID generated by the database. I tried what was suggested in this question, but it leads to the same issue, of unique non-database IDs
It's also not possible to select from the JDBC again, as string1 and string2 may not be unique. Nor is it possible to change the database. For instance, I can't change it to be UUID, and I can't add a trigger for it. It's a legacy database that we can only use
How can I achieve this? Is this possible with Apache Spark?
I'm not a Java specialist so you will have to look into the database layer on how to proceed exactly but there are 3 ways you can do this:
You can create a store procedure if the database server you are using is capable of (most do) and call it from your code.
Create a trigger that returns the id number on the first insertion and use it in your next DB insertion.
Use UUID and use this as the key instead of the database auto generated key.
I am working on an application running Grails 2.4.5 and Hibernate 3.6.10.
There is a domain object that has a child PersistentMap. This map stores 4
key-value pairs where the value is always a String.
In our dev and test environments everything works fine and then occasionaly
the persistent map starts returning "1" for either the key or the value.
The other values in the parent domain object are fine. The problem has been
resolved when it occurs by updating one of the records for the map directly
in the database. This makes me think its a cacheing issue of some sort,
but I haven't been able to recreate it in a local environment.
The database underneath is MySQL.
The following is not the actual code but is representative of the structure.
class MyDomain {
static belongsTo = [owner: Owner]
static hasMany = [relatedDomains: RelatedDomain]
Set relatedDomains = []
Map flags = [:]
String simpleItem
String anotherItem
static constraints = {
owner(nullable: true)
relatedDomains(nullable: true)
flags(nullable: true)
simpleItem(nullable: true)
anotherItem(nullable: true)
}
}
This results in a couple of tables (ignoring RelatedDomain and Owner):
mydomain table
| id | version |owner_id|simple_item|another_item |
|-------|-----------|--------|-----------|-------------|
| 1 | 1 | 1 | A value |Another value|
mydomain_flags table
|flags| flags_ids | flags_elt |
|-----|-----------|-------------|
| 1 | KEY_ONE | VALUE_ONE |
| 1 | KEY_TWO | VALUE_TWO |
| 1 | KEY_THREE | VALUE_THREE |
When the MyDomain instance is retrieved the flags map will have:
[ "KEY_ONE": "VALUE_ONE", "KEY_TWO": "VALUE_TWO", "KEY_THREE" :"VALUE_THREE"]
Occasionally the map contains:
[ "KEY_ONE": "1", "KEY_TWO": "1", "KEY_THREE" :"1"]<br/>
OR
[ "1": "VALUE_ONE", "1": "VALUE_TWO", "1" :"VALUE_THREE"]
The rest of the data in the MyDomain instance is correct. It is just the flags map that seems to have an issue. The application only reads the information for the mydomain and flags, it never updates the data. It's basically configuration data for the application.
Has anyone else seen behavior like this? I don't know if its related to hibernate (version 3.6.10) or Grails/Gorm or both. I've been unable to reproduce it locally but it has happened in two separate environments.
I tracked it down to an issue with hibernate. The aliases generated for the persistent map resulted in the same alias for the key and the element. This is because the aliases are based on a static counter in the org.hibernate.mapping.Table class (in 3.6.10). The reason it was sporadic was because Grails loads all the domain classes into a HashSet and then iterates over the set binding each one. Since the Set is unordered sometimes the domain class with the persistent map would be the 3rd class mapped resulting in a key alias identical to the element alias.
This problem was fixed in Hibernate version 4.1.7
https://hibernate.atlassian.net/browse/HHH-7545
To get around the problem in Grails, I subclassed the GrailsAnnotationConfiguration class and in the constructor, created and discarded 10 Hibernate Table instances. This incremented the static counter to a safer seed value prior to loading the Grails domain classes.
Is it possible index a complete database without mentioning the table names explicitly in the data-config.xml as new tables are added everyday and I cannot change the data-config.xml everyday to add new tables.
Haven table names based on the date smells like there is something wrong in your Design. But given this requirement in your question you can add Data to your solr server without telling you have a DB. You just have to make sure you hav a unique ID for the data record in you solr Server with whom you can identify the corresponding record in your DB, something like abcd_2011_03_19.uniqueid. You can post the data to solr in Java in solrj or just plain xml or json.
Example:
--------------
| User Input |
--------------
|post
V
-----------------------------------
| My Backend (generate unique id) |
-----------------------------------
|post(sql) |post (e.g. solrj)
V V
------ --------
| DB | | solr |
------ --------
My ascii skillz are mad :D