Add queries and accessor

pyproject.toml.unversioned

@@ -191,13 +191,16 @@ packages = [
     "delete_feature.py",
     "upload_sync_small.py",
     "collection.py",
+    "load_query.py",
 ]
 "spatialprofilingtoolbox.db.data_model" = [
     "metaschema.sql",
     "drop_metaschema.sql",
     "create_roles.sql",
     "create_views.sql",
     "drop_views.sql",
+    "load_query.sql",
+    "load_query_breakdown.sql",
     "fields.tsv",
     "grant_on_tables.sql",
     "performance_tweaks.sql",

spatialprofilingtoolbox/db/data_model/load_query.sql

@@ -0,0 +1,21 @@
+SELECT
+SUM(
+  (
+    xpath(
+      '/row/c/text()',
+      query_to_xml(
+        format(
+          'select count(*) as c from %I.%I',
+          schema_name,
+          'quantitative_feature_value_queue'
+        ),
+        FALSE,
+        TRUE,
+        ''
+      )
+    )
+  )[1]::text::int
+) as total_jobs_in_queue
+FROM
+  default_study_lookup.study_lookup
+;

spatialprofilingtoolbox/db/data_model/load_query_breakdown.sql

@@ -0,0 +1,20 @@
+SELECT
+  schema_name,
+  (
+    xpath(
+      '/row/c/text()',
+      query_to_xml(
+        format(
+          'select count(*) as c from %I.%I',
+          schema_name,
+          'quantitative_feature_value_queue'
+        ),
+        FALSE,
+        TRUE,
+        ''
+      )
+    )
+  )[1]::text::int AS number_jobs_in_queue
+FROM
+  default_study_lookup.study_lookup
+;

spatialprofilingtoolbox/db/scripts/load_query.py

@@ -0,0 +1,53 @@
+"""Utility to print the SQL query that returns the number of computation jobs in the queue."""
+
+import argparse
+from importlib.resources import as_file
+from importlib.resources import files
+
+
+def _get_data_model_file(filename: str) -> str:
+    source_package = 'spatialprofilingtoolbox.db.data_model'
+    with as_file(files(source_package).joinpath(filename)) as path:
+        with open(path, encoding='utf-8') as file:
+            script = file.read()
+    return script
+
+def get_load_query() -> str:
+    return _get_data_model_file('load_query.sql')
+
+
+def get_load_query_breakdown() -> str:
+    return _get_data_model_file('load_query_breakdown.sql')
+
+
+def parse_args():
+    parser = argparse.ArgumentParser(
+        prog='spt db load-query',
+        description='Get a SQL query which returns the size of the computation job queue, suitable as a measure of load.',
+    )
+    group = parser.add_mutually_exclusive_group(required=True)
+    group.add_argument(
+        '--all',
+        action='store_true',
+        default=False,
+        help='If selected, the SQL query will be the one which sums all job queue sizes for a single total.',
+    )
+    group.add_argument(
+        '--breakdown-by-dataset',
+        action='store_true',
+        default=False,
+        help='If selected, the SQL query will return the job queue sizes broken down by dataset.',
+    )
+    return parser.parse_args()
+
+
+def main():
+    args = parse_args()
+    if args.all:
+        print(get_load_query())
+    if args.breakdown_by_dataset:
+        print(get_load_query_breakdown())
+
+
+if __name__=='__main__':
+    main()