POSC Specifications
|
Relational Implementation |
How to Read the Epicentre Relational Implementation Dictionary
This section describes the conventions used in the documentation of the
Sample Relational Implementation. It includes an
explanation of the structure and content of the table descriptions. The
table documentation is derived from the projected DDL and is intended to
assist in the understanding of the relational implementation. In addition
to this documentation, a complete set of DDL
is delivered as text files.
An example of a table in the relational implementation of Epicentre is:
This specified the kinds of parameters used by coordinate transformation methods.
Examples of these parameters are: scale factor, false easting, central meridian, rules, etc.
- instance_s (PK, M: CHAR VARYING(19))
- Surrogate key of the table.
- identifier (M: CHAR VARYING(80))
- technical_reference.identifier
The name of the instance.
- description (O: CHAR VARYING(2000))
- e_and_p_data.description
A remark or comment about the instance.
- instance_create_date (O: TIMESTAMP)
- e_and_p_data.instance_create_date
This is the date that this instance was created. This date is defined by the source if imported, or is the date the instance is created if a new instance.
- instance_creator (O: CHAR VARYING(80))
- e_and_p_data.instance_creator
This is the person, company or application that created this instance. This identifies the party responsible for loading this instance.
- last_updated (O: TIMESTAMP)
- e_and_p_data.last_updated
This is the date that this instance was last updated. This value should be updated when any part of this instance is altered (except for inverse relationships).
- last_updated_by (O: CHAR VARYING(80))
- e_and_p_data.last_updated_by
This records the person or application making the update to this instance.
- source (O: CHAR VARYING(80))
- e_and_p_data.source
The provider of this instance, which is usually a data provider for imported/purchased data. If this instance is provided by POSC, then this attribute must be "POSC".
- source_content (O: CHAR VARYING(80))
- technical_reference.source_content
This is the original source of the data. This is the person, company or application that defined or specified the data (content) for this instance and is considered to be responsible for it. For example, POSC, EPSG, API, ISO, etc. This may be the same as or different from the provider of the instance (e.g., POSC).
- source_reference (O: CHAR VARYING(2000))
- technical_reference.source_reference
The reference used by source to provide the standard instance, such as Petroleum Industry Data Dictionary (PIDD), Websters Ninth New Collegiate Dictionary, etc.
- status (O: CHAR VARYING(11))
- technical_reference.status
The status of this instance in the version of Epicentre running in a data store. This is an enumerated datatype for which the following are the possible values: current, provisional, deprecated. Current - use without restriction. Provisional - use with caution, this value is for comment and may not appear in future releases of Epicentre. Deprecated - avoid use if possible, it is planned to remove this value in the next major release of Epicentre.
- naming_system (FNK, O: CHAR VARYING(80))
- aliasable_technical_reference.naming_system
The naming system in which the identifier is specified and determined to be unique.
Defines a foreign key to table naming_system.
- r_parameter_attribute (FNK, O: CHAR VARYING(80))
- transformation_parameter.ref_parameter_attribute
This designates the type of attribute in the transformation parameter value that should be used for this parameter. If not specified then an attribute of any type may be used for the parameter value (e.g., a parameter such as "A1" may be used in many contexts).
Defines a foreign key to table r_parameter_attribute.
- version_s (FSK, O: CHAR VARYING(19))
- technical_reference.version
This describes the version of this instance as defined by the provider.
Defines a foreign key to table r_version.
Table is related to: data_collection_content, derived_interest_makeup, document_specification_part, @graphical_element, object_activity_involvement, technical_reference_alias, transformation_parameter_usage
Primary Key Constraint on: INSTANCE_S
Fully implemented Unique Constraint on: IDENTIFIER
As each table is presented, the table name is given in uppercase, boldface
type. The long name of the corresponding Epicentre entity follows immediately
in parenthesis, followed by a description of the table. Next, the columns
that compose the table are described. The tables that have a foreign key
from this table follows. The intersections that connect this table to other
tables are then given. The definition of table constraints completes the
description of each table.
Columns
Following the description of the table, the columns are described by a
list of entries, one for each column in the table. Each column is described
by column name in bold, lowercase. Following the column name, in parentheses,
is a list of column qualifiers that are separated by commas and terminated
by a colon. The column qualifiers have the following meaning:
-
Optionality qualifier - this is either O or M. O means this column
is optional (can be null) and M means mandatory (not null).
-
Key indicator. This can be PK, or absent. PK means primary key for
this table, absent means this column is not used as a key.
-
Foreign key indicator - This can be FNK, FSK or absent. If this
column is there to provide a relationship to another table and the relationship
uses the surrogate key of the related table then this indicator is set
to FSK; if the column provides a relationship to another table via the
natural key of the other table, then this indicator is set to FNK, otherwise
is left absent.
The data type will follow the colon. This can be any one of the SQL 92
specified data types, e.g. CHAR VARYING, DATE, TIMESTAMP, FLOAT, DECIMAL,
etc. The declared data type is followed by a length qualifier in parentheses
where appropriate.
The first indented line following the column name will contain the logical
attribute name, preceded by its parent entity, that this column was projected
from.
The next indented line is the description of the column.
When the column is a foreign key, then the next indented line will contain
the phrase "Defines a foreign key to table" followed by the name of the
table that is referenced. Where the name is prefixed by an @, then this
is the name of a list of possible tables this is related to - this is a
hypertext link that will expand the contents of the list.
Table is related to
This section contains a list of tables that are related to this table,
i.e., other tables that contain a foreign key from this table. Each item
in this list corresponds to a relationship to the table that does not appear
as a foreign key in the table. Where a name is prefixed by an @, then this
is the name of a list of possible tables this is related to - this is a
hypertext link that will expand the contents of the list.
Intersection tables
This is a list of the tables that are related to this table and were created
during the projection process to implement a many-to-many relationship.
Table Constraints
This section specifies one or two SQL constraints. The first places a uniqueness
constraint on the surrogate key (The surrogate key is considered to be
the primary key of the table.). The second statement (if present) defines
the combined values of the columns forming the secondary key to be unique
for each row entry.
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