Opasnet base structure

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Scope

Opasnet base is a storage and retrieval system for variable results. What is the structure of Opasnet base such that it enables the following functionalities?

1. Storage of results of variables with uncertainties when necessary, and as multidimensional arrays when necessary.D↷
2. Automatic retrieval of results when called from Opasnet wiki or other platforms or modelling systems.
3. Description and handling of the dimensions that a variable may take.
4. Storage and retrieval system for items that are needed to calculate the results of variables.(?)
5. A platform for planning computer runs about variable results based on the update need, CPU demand, and CPU availability.

Definition

Data

Software

Because Opasnet base will contain very large amounts of mostly numerical information, the state-of-the-art structure is a SQL database. Because of its flexibility, ease of use, and cost, MySQL is an optimal choice among SQL software. In addition to the database software, a variable transfer protocol is needed on top of that so that the results of variables can be retrieved and new results stored either automatically by a calculating software, or manually by the user. Fancy presenting software can be built on top of the database, but that is not the topic of this page.

Storage and retrieval of results of variables

The most important functionality is to store and retrieve the results of variables. Because variables may take very different forms (from a single value such as natural constant to an uncertain spatio-temporal concentration field over the whole Europe), the database must be very flexible. The basic solution is described in the variable page, and it is only briefly summarised here. The result is described as

  P(R|x1,x2,...) 

where P(R) is the probability distribution of the result and x₁ and x₂ are defining locations of a dimension where a particular P(R) applies. Typically locations are operationalised as discrete indices. A variable must have at least one dimension. Uncertainty about the true value of the variable is operationalised as a random sample from the probability distribution, in such a way that the samples are located along an index Sample, which is a list of integers 1,2,3...n, where n=number of samples.

Table and field names

Principles:

• The names should be as short as possible: three letters.
• Tables that are only connecting two substance tables (i.e. tables for making many-to-many relationships) have a name that is a combination of the two, with six letters.
• Identifiers are named like Var_id where Var is the name of the table.
• Substantive fields may have longer names.
• Substantive fields do not repeat the table name unless there is a possibility to mix two fields in different tables.
• The field endings have the following meaning:
  • _id: the identifier of the row in RDB, a sequential number in the table.
  • _name: the identifier for Analytica, format: wiki link+page (e.g. Op_en2356)
  • _title: a longer, descriptive title
  • page: the page identifier from Opasnet
• QUESTION: Should the name of Var be changed into Obj? Reasoning: in practice, all substantive information of Dimension is located in the Var table, and the Dim table only contains the information about the Dim_id. This could be operationalised in another way: all objects locate in the Obj table, which also contains a new field Type. Type is the type of object (Variable, Dimension, Index, Class, Assessment)

In practice the tables and fields would look like this:

Tables:

• Variable -> Var
• Result -> Res
• Location -> Loc
• Dimension -> Dim
• Index -> Ind
• Rows -> Row
• Loc_of_result -> Locres (the location of each result)
• Run -> Run
• Run_list -> Runres (the run of each result)
• Wiki_location -> Wik
• Risk assessment -> Ra
• RA_vars -> Ravar (the risk assessment of each variable)
• RA_indices -> Raind (the risk assessment of each index)
• Causality -> do we actually need this?
• Formula -> do we actually need this?
• Data -> do we actually need this?

Fields (only those are listed that are actively used and should be changed):

• Var table: Remove the "Var_" from all fields except Var_id.
• Page_id -> Page (because this is rather a substantive field than an identifier; there is no table called "Page")
• Result_id -> Res_id
• Dimension table: Dimensions are actually variables themselves. Therefore, all substantive content should be moved to Var; we don't need any more Dim_name, Dim_title, Dim_unit, Page_id and Wiki_id in this table. We need to add Var_id field, which tells where in the Var table the info of each dimension is found.
• Row_number -> Row
• Run table: Remove "Run_" from the field names except Run_id
• Runres table: Run_order -> order (do we actually need this field?)

Result

Opasnet base is a en:MySQL database located at http://base.opasnet.org.

Table structure

Variable Information about variable attributes and validity FIELD TYPE EXTRA Var_id mediumint(8) primary Var_name varchar(20) unique Var_title varchar(100) Var_scope varchar(1000) Var_unit varchar(16) Page_id mediumint(8) Wiki_id tinyint(3)	Result All results are stored in this table. Each value of a result of a variable has an own row. FIELD TYPE EXTRA Result_id int(10) primary Var_id mediumint(8) Result varchar(1000) Sample smallint(5)	Location The location of the result along a particular dimension. FIELD TYPE EXTRA Loc_id mediumint(8) primary Dim_id mediumint(8) Location varchar(1000)
Dimension Information about dimensions FIELD TYPE EXTRA Dim_id mediumint(8) primary Dim_name varchar(100) Dim_title varchar(100) Dim_unit varchar(16) Page_id mediumint(8) Wiki_id tinyint(3)	Index Information about indices FIELD TYPE EXTRA Ind_id int(10) primary Ind_name varchar(100) Dim_id mediumint(8)	Rows Information about rows of indices FIELD TYPE EXTRA Ind_id int(10) unique Row_number int(10) unique Loc_id mediumint(8)
Loc_of_result explanation coming... FIELD TYPE EXTRA Loc_id mediumint(8) unique Result_id int(10) unique Var_id mediumint(8) Ind_id mediumint(8) N mediumint(8) Run_id mediumint(8)	Run Information about the computer runs FIELD TYPE EXTRA Run_id mediumint(8) primary Run_date date Run_who varchar(50) Run_method varchar(200)	Run_list List of variables in a run FIELD TYPE EXTRA Run_id int(16) Run_order varchar(100) Var_id int(16) Result_id int(10)
Wiki_location Defines URL of a wiki where object is linked FIELD TYPE EXTRA Wiki_id tinyint(3) primary URL varchar(60) Wiki_name varchar(20)	Risk_assessment Attributes of a risk assessment. Not actively used yet. FIELD TYPE EXTRA RA_id smallint(5) primary RA_name varchar(100) RA_scope varchar(1000) RA_started date RA_finished date	RA_vars Defines the variables used in a risk assessment. Not actively used yet. FIELD TYPE EXTRA RA_id smallint(5) unique Var_id mediumint(8) unique
RA_indices Defines the indices used in a risk assessment. Not actively used yet. FIELD TYPE EXTRA RA_id smallint(5) unique Ind_id int(10) unique	Causality Defines the parents in the causal chain. Not actively used yet. FIELD TYPE EXTRA Var_id mediumint(8) Causality_date date Parent_id mediumint(8)	Formula Defines the formulas of the variables. Not actively used yet. FIELD TYPE EXTRA Var_id mediumint(8) Formula_date date Software varchar(100) Formula varchar(100)
Data Defines the data of the variables. Not actively used yet. FIELD TYPE EXTRA Var_id mediumint(8) Data_date date URL varchar(100)

See also

These texts could be moved to separate pages.

Making value-of-information analyses in Opasnet base

Value of information (VOI) is a decision analysis tool for estimating the importance of remaining uncertainty for decision-making. Result database can be used to perform a large number of VOI analyses, because all variables are in the right format for that: as random samples from uncertain variables. The analysis is done by optimising an indicator variable by adjusting a decision variable so that the variable under analysis is conditionalised to different values. All this can in theory be done in the result database by just listing the indicator, the decision variable, and the variable of interest. Practical tools should be developed for this. After that, systematic VOI analyses can be made over a wide range of environmental health issues.

Analysing the change in the quality of a variable result in Opasnet base

All results that have once been stored in the result database remain there. Old results can be very interesting for some purposes:

• The time trend of informativeness and calibration (see performance) can be evaluated for a single variable against the newest information.
• Critical pieces of information that had a major impact on the informativeness and calibration can be identified afterwards.
• Large number of variables can be assessed and e.g. following questions can be asked:
  • How much work is needed to make a variable with reasonable performance for practical applications?
  • What are the critical steps after which the variable performance is saturated, i.e., does not improve much despite additional effort?

Some useful syntax

• http://www.baycongroup.com/sql_join.htm
• Opasnet base connection.ANA for Analytica: for writing and reading variable results into and from the database. Writing requires a password. For SQL used in the model, see the model page.
• Some historical queries

List all dimensions that have indices, and the indices concatenated:

<sql-query display="1"> Select Dim_name, dim_title, dim_unit, Group_concat(Ind_name order by ind_name separator ', ') as Indices from Dimension, `Index` where Dimension.dim_id = `Index`.Dim_id group by Dim_name order by Dimension.dim_id </sql-query>

List all indices, and their locations concatenated:

<sql-query display="1">

Select Dim_name, Dim_title, Dim_unit, Ind_name, Group_concat(Location order by row_number separator ', ') as Locations 
from `Index`, Location, Rows, Dimension
where `Index`.ind_id= Rows.ind_id and Rows.loc_id = Location.loc_id and `Index`.dim_id = Dimension.dim_id
group by Ind_name
order by Dim_name, `Index`.ind_name

</sql-query>

List all variables and their runs, and also list all dimensions (concatenated) used for each variable for each run.

<sql-query display="1">

SELECT Var_id, Run_id, Var_name, Var_title, GROUP_CONCAT(Dim_name SEPARATOR ', ') as Dimensions, n, Run_method
FROM
   (SELECT Loc_of_result.Var_id, Run_list.Run_id, Var_name, Var_title, Dim_name, n, Run_method
   FROM Loc_of_result, Run_list, Run, Variable, Location, Dimension
   WHERE Loc_of_result.Result_id = Run_list.Result_id 
   AND Run_list.Run_id = Run.Run_id
   AND Loc_of_result.Var_id = Variable.Var_id
   AND Loc_of_result.Loc_id = Location.Loc_id 
   AND Location.Dim_id = Dimension.Dim_id
   GROUP BY Dimension.Dim_id, Loc_of_result.Var_id, Run_list.Run_id
   ORDER BY Loc_of_result.Var_id, Run_list.Run_id) as temp1
GROUP BY Var_id, Run_id

</sql-query>