Questions tagged [database-metadata]

Metadata is "data about data". In database terminology, this set of metadata is referred to as the catalog. The SQL standard specifies a uniform means to access the catalog, called the information schema, but not all databases implement it, even if they implement other aspects of the SQL standard. For an example of database-specific metadata access methods, see Oracle metadata.

Meta Data:

Metadata is “data about data”. An item of metadata describes the specific characteristics about an individual data item. In databases, metadata describes the structural components of tables and their elements. For example, metadata about an element could include data types, name of data, size and many more characteristics about that element. It would also give information about the tables the database is storing, information, such as length of fields, number of columns, where the tables are located and other pertinent information. One of the main uses for met data is to provide a link between the information creator and the information users. Metadata allows the users to speed up the search for individual data. This is done by being able to set parameter for searches, allowing the filtering of unwanted information. Metadata can be stored either internally, in the same file as the data or externally, in a separate area. Both have advantages and disadvantages. If the data is stored internally, the metadata is together with the data making more easily accessible to view or change. However, this method creates high redundancy. If metadata is stored externally, the searches can become more efficient. There is no redundancy but getting to this metadata may be a little more technical. There are certain formats that must be used, such as Uniform Resource Identifier(URI) to get to the metadata if this format is not used the metadata becomes inaccessible. All the metadata is stored in a data dictionary or a system catalog. All programs that access data in the database work through a DBMS. The DBMS uses the data dictionary to look up the required components and relationships. Any changes made to the database structure are automatically recorded in the data dictionary. This makes the data dictionary manager’s job a lot easier because any modification of programs that are affected by the changed structure is not necessary.

Metadata at the most basic level is simply defined as “data about data”. An item of metadata describes the specific characteristics about an individual data item. In the database realm, metadata is defined as, “data about data, through which the end-user data are integrated and managed.” (Rob & Coronel, 2009) Metadata in a database typically store the relationships that link up numerous pieces of data. “Metadata names these fields describes the size of the fields, and may put restrictions on what can go in the field (for example, numbers only).” (Sheldon, 2001).

“Therefore, metadata is information about how data is extracted, and how it may be transformed. It is also about indexing and creating pointers into data. Database design is all about defining metadata schemas.” (Sheldon, 2001) Metadata can be stored either internally, in the same file as the data, or externally, in a separate area. If the data is stored internally, the metadata is together with the data, making it more easily accessible to view or change. However, this method creates high redundancy. If metadata is stored externally, the searches can become more efficient. There is no redundancy but getting to this metadata may be a little more technical.

All the metadata is stored in a data dictionary or a system catalog. The data dictionary is most typically an external document that is created in a spreadsheet type of document that stores the conceptual design ideas for the database schema. The data dictionary also contains the general format that the data, and in effect the metadata, should be. Metadata is an essential aspect of database design, it allows for increased processing power, due to the fact that it can help create pointers and indexes.

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Database Meta tools

I'm now working with a legacy database which is missing, among almost everything you'd expect from a decent SQL relational DB, any documentation or metadata. I can't make changes to the DB schema, except my local test copy, as it exists at many…
kyle
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How to make schema graph with sqlalchemy_schemadisplay?

How to make schema graph? meta = MetaData() meta.reflect(bind=engine, views=True, resolve_fks=False) graph = create_schema_graph( metadata=meta, show_indexes=False, concentrate=False, …
John Doe
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How to query only "Label" property of DisplayName from Dynamics 365 database metadata?

I want to request entities metadata from Dynamics 365 database. I want to get LogicalName, DisplayName and list of Attributes with their Logical and Display names as well. My current request looks like…
Sun of A beach
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ENtity meta data not found

I am getting No entity metadata found error for the second database table that i am trying to connect I am trying TypeOrmModule.forRoot to give the details I am able to connect each tables individually by commenting the other. But when I add both, I…
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Where to find user-defined types in table catalogue views

Of sys.objects BL says "Contains a row for each user-defined, schema-scoped object that is created within a database" The following shows the creation of 2 schema scoped objects, a table and a type, but querying something_here only shows up the…
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Configuring oracle database as airflow metadata backend db does not create airflow tables when deployed from docker

I am running a proof of concept to connect airflow and oracle database to store airflow metadata. From the documentation (https://airflow.apache.org/docs/apache-airflow/stable/howto/set-up-database.html#database-uri) I have seen that mostly…
NikSp
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Find the folder name and mapping name details impacted by particular target table in informatica

I need to find the informatica objects dependent on one table. Please help me with the metadata sql query to get the folder name detail and mapping name which are impacted by this specific target table. I am not aware of the informatica folder name.…
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Wrong Oracle database and JDBC Driver version printed by Hibernate SettingsFactory

Our Java program has been installed on the RHEL 8.5 OS platform. And for database operations in our application, we use hibernate (version hibernate-3.2.7.ga.jar). Additionally, we are utilizing the JDBC driver(version 19.15) and the Oracle…
Learner
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How to get metadata of a document/Collection from Firestore Database in Firebase using code snippets

I am trying to get all the metadata information of a document or a Collection present in a Firestore Database in Firebase using NodeJs or Python Code snippets. I am able to get size of document using the following const sizeof =…
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Add metadata tag to teradata objects

I have several stored procedures in Teradata that I wish to label. Therefore, I'm looking for a way to add metadata to an object in Teradata. I've been looking into Teradata's Data Dictionary, but it seems the only way is to add labels as…
Frank
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Redshift - Group Level Permissions on a Schema

I created two Groups (Confirmed using SELECT groname FROM pg_group) Test_Group_A Test_Group_AB Created two External Schemas (Confirmed using SELECT schemaname FROM svv_external_schemas) External_Schema_A External_Schema_B Granted permissions to…
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Getting metadata from Views from Microsoft SQL Server

Is there a way to get from SQL Server metadata information about the dependencies of a view, in which manner are linked together (inner join, left join, right join) and the join's keys? (that_table.Id = my_table.That_tableId AND X.Id = Z.XId)…
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Databricks - Find the delta tables which were recently updated

I am working on a use case in Databricks - GCP, where I am trying to find out the delta tables in a schema/database in Databricks which were updated in last 1 day. I used DESCRIBE DETAIL and ran this command in loop for all the table…
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SQLAlchemy 1.4 abstracting MetaData.reflect into function not returning MetaData object?

I have a class that acts as a PostgreSQL database interface. It has a number of methods which do things with the MetaData, such as get table names, drop tables, etc. These methods keep calling the same two lines to set up MetaData. I am trying to…
alphaomega
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list database tables that don't need to be qualified with schema name

I connect to a PostgreSQL server with: jdbc:postgresql://127.0.0.1/mydb?currentSchema=app96. I need to list tables that are present and create those that are missing during the initialization of my server. Here's my code: final ResultSet rs2 = …
basin
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