The following dialog is displayed when you specify an "Extended GoldSim Database" for the Data Source A source of data external to your GoldSim model that can be automatically imported into GoldSim elements. External data sources are either spreadsheets, text files, databases or DLLs. for an element and click on the Database tab in the properties dialog for Data, Stochastic or Lookup Table element A type of input element that allows you to define your input in terms of a lookup table (i.e., a response surface). (the three elements for which this type of data source can be specified):
As described in Appendix E of the GoldSim User’s Guide, like the Simple GoldSim database, the Extended GoldSim database has a specific structure in which a string in a field in one of the database tables must uniquely match the ID of the element you wish to link to.
That is, when you link an element to an Extended GoldSim database, GoldSim locates the data to download within the database by using the element's ID. Unlike a Generic database, you do not need to manually indicate the record and field you wish to access from within GoldSim.
In addition, the units of data being downloaded are specified directly in the database, and need not be identified on the Database tab (although they must be consistent with the specified dimensions An output attribute for an element that defines the dimensionality (in terms of Length, Time and other fundamental dimensions) of the output. for the element as defined on the Definition tab).
Note: Particular care must be taken when importing Stochastics from a database, as different Stochastics could have different dimensions (e.g., a Binomial is always dimensionless; a Boolean is always a condition). If a Stochastic is defined in your model as a particular type of distribution whose output is inconsistent with that of the distribution that you are trying to import from the database, GoldSim will display an error.
Note: Care must also be taken when importing Stochastics that represent temperatures. This is because temperatures have an absolute reference (i.e., absolute zero). Differences between temperatures are expressed in “deg” units (Cdeg, Fdeg). This can lead to errors when importing Stochastics, since GoldSim assumes a single unit for the distribution parameters, while some types of distributions would require two different types of units. For example, a Normal distribution representing a temperature would require the Mean to be specified in absolute units (e.g., C) and the Standard Deviation The square root of the variance of a distribution. The variance is the second moment of the distribution and reflects the amount of spread or dispersion in the distribution. to be specified in difference units (e.g., Cdeg). If faced with this problem, there are several approaches for addressing this: 1) Use a distribution type where all parameters have the same units (e.g., triangular, uniform, cumulative); or 2) Specify and import the distributions as dimensionless and then apply a unit to the sampled value using an Expression element.
Because an Extended GoldSim database is so highly structured, if the database is properly defined, linking and downloading from it requires only two steps:
- Select the appropriate data source from the Database drop-down list (all defined data sources will be listed).
- Press the Download Now button to download the data.
GoldSim notes whether the download was successful (and, if successful, displays the date and time of the download).
The More info... button provides some additional information regarding a successful download (the effective date and the Run Log Text that is stored with a GoldSim model once it has been run. It contains basic information regarding the simulation, and any warning or error messages that were generated. strings associated with the data).
As discussed in detail in Appendix E of the GoldSim User’s Guide, for an Extended GoldSim database, you can create multiple records for a particular item of data, each with a different "Effective Date". This allows you to keep a record of how particular inputs to your model have been modified.
The checkbox allows you to download data associated with a specific Effective Date:
- If checked, you must specify a date, and Download Now will download the data with the most recent Effective Date on or before the specified date.
- If cleared, Download Now will download the data with the most recent Effective Date on or before the default Effective Date for the element, as specified in the GS_Parameter table of the database (described in Appendix E).
- If cleared and no default Effective Date is specified in the database for the element, Download Now will download the data with the most recent Effective Date
Note: As pointed out above, when you link an element to an Extended GoldSim database, GoldSim locates the data to download by using the element's ID alone (no path is specified in the database). Hence, in order for GoldSim to download the element's definition from the database, a record in the Element ID field of the database must match the GoldSim element ID exactly (although the comparison is not case-sensitive). This implies that you cannot have multiple elements with identical names (e.g. , in two localized containers) which are both being linked to an Extended GoldSim database.
The file ExtendedDatabase.gsm in the General Examples/Database folder of your GoldSim directory (accessed by selecting File | Open Example... from the main menu) includes examples of how to download data from an Extended GoldSim database.