Schema and table semantics

Since the datastore types that MetaModel support are widely different, one might question "what does a schema or a table mean?" for eg. Excel spreadsheets, CSV files etc.

On this page we will answer such questions. In the table below there's a list of MetaModel modules and an explanation of the semantics of schemas and tables.

Module

Schema

Table

JDBC

A database schema, as defined by JDBC.

A database TABLE, VIEW or other tabular structure in a schema.

OpenOffice

A database schema, as defined by JDBC.

A database TABLE, VIEW or other tabular structure in a schema.

CSV

A handle to the CSV file. If the file does not exist, schema will be empty. Always has default schema and virtual information schema.

The actual file structure, based on the column name line.

Excel

A handle to the Excel spreadsheet. If the file does not exist, schema will be empty. Always has default schema and virtual information schema.

A sheet in the spreadsheet

Fixed width

A handle to the Fixed value width file. Always has default schema and virtual information schema.

The actual file structure, based on the column name line.

Access

A handle to the Access file. Always has default schema and virtual information schema.

The tables in the Access database file.

XML (SAX)

A handle to the XML file. Always has default schema and virtual information schema.

A certain position in the XML tree, defined by a user's xpath expression. Each table also has xpath expressions for each column, which define the values of the rows in a table.

XML (DOM)

A handle to the XML file. Always has default schema and virtual information schema.

All tables are virtual representations of recurring combinations of XML elements. The actual generation of tables depend on whether you perform manual or automatic "flattening" (denormalization) of tables

MongoDB

A MongoDB database.

A MongoDB collection with a virtual table model, which represent the properties of the documents in the collection.

Salesforce.com

A handle to the web services of Salesforce

A type of Salesforce.com SObject.

SugarCRM

A handle to the web services of SugarCRM

A SugarCRM 'module'.

Semantics of "Create table"

In addition to understanding "what is a table?" it is also useful to know what it means to "create" a table, as it is facilitated by MetaModel 2.0 and onwards.

Module

Create table semantics

JDBC

Issue a CREATE TABLE statement to the database.

CSV

Create or overwrite the CSV file with a (new) table structure. If multiple files should be created, then create a new CsvDataContext and issue the createTable operation there.

Excel

Creates a new sheet in the Excel spreadsheet.

MongoDB

Creates a new collection in the MongoDB database.

CouchDB

Creates a new CouchDB database.

POJO (Java objects)

Creates a new collection of Java objects (Map based).

SchemaAndTableSemantics (last edited 2013-08-01 09:51:56 by KasperSorensen)