When working with large drillhole databases, it’s often necessary to subset the data to a specific area or group of holes — without breaking the relationship between collars, surveys, and interval tables.
This workflow outlines a simple, reliable way to subset an entire drillhole database using the collar file as the control, ensuring all associated downhole data remains consistent.
Overview of the Workflow
The core idea is straightforward:
Use the collar file as the authoritative filter, then propagate that selection to all associated drillhole tables.
This is achieved by:
Coding the collars you want to keep
Writing that code into the drillhole database
Using the Drillhole Subset tool to extract a clean, consistent database in one step
Step-by-Step Workflow
1. Code the Selected Collars
Load the collar file as a point layer.
Select the drillhole collars to include (for example, using a spatial selection, polygon, or boolean operation).
Assign a code to the selected collars (e.g.
Flagged = 1).
If needed, create a new field in the collar file (such as Flagged) to store this value.
This field will be used as the filter criterion in the next steps.
Figure 1: Select the drillholes of interest and code them with a value (e.g. 1). This can be done via manual selection or polygon assign tool in Micromine
2. Add the code as a new collar attribute to the Drillhole Database
Go to Drillhole | Edit | Edit Drillhole Database.
Add the collar attribute with the new field (e.g. Flagged)
At this stage, the drillhole database contains an explicit attribute that defines which holes should be included.
Figure 2: Adding a new collar attribute to the existing Drillhole Database
3. Subset the Drillhole Database
Navigate to:
Drillhole | Filter | Subset
(or via Viewer | Database | More when the validation viewer is open)
Input
Database: Select the drillhole database to be subset.
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Filter: Create a filter where the collar attribute meets your condition
(for example:Flagged= 1).Filters can be created or reviewed via the filter forms.
This filter now controls which records are considered “in scope”.
Output
Database: Specify a new output database to write the filtered records to.
If the database exists, it will be overwritten.File suffix: Specify a suffix to generate unique output file names.
If overwriting an existing database and generating new files, output file names must match the original database file names. Otherwise, you will be prompted to delete the existing database, change the database name, or adjust the file suffix.
Figure 3: Subsetting an existing drillhole database using a collar-based filter.
Exceptions (optional)
You may optionally generate an Exceptions database containing records that do not pass the filter.
The output and exception file suffixes must not be the same.
Report file
Specify a report file to log the success or failure of records processed for each file in the database.
Click Run to execute the process.
Result
The Subset process will automatically:
Subset the Collar table
Subset the Survey table
Subset all Interval tables (assay, lithology, etc.)
All resulting tables remain internally consistent, with no orphaned records.
Figure 4: Subset drillhole database extracted from an Area of Interest.
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