Skip MDM candidate search if parameters are missing (#5658)

* Issue #5657

Skip an MDM candidate search if any search parameter is missing (as per documentation,
and to avoid non-performant searches), rather than only when all of them are missing.

* Address the unit test failure.

* Add credit for #5658

---------

Co-authored-by: James Agnew <jamesagnew@gmail.com>

hapi-fhir-docs/src/main/resources/ca/uhn/hapi/fhir/changelog/7_4_0/5658-skip-mdm-candidate-search-if-params-are-missing.yaml

@@ -0,0 +1,6 @@
+---
+type: perf
+issue: 5658
+title: "The MDM candidate search will now be skipped if data for required
+  search parameters is not present. Thanks to Adrienne Sox for the 
+  pull request!"

hapi-fhir-jpaserver-mdm/src/main/java/ca/uhn/fhir/jpa/mdm/svc/candidate/MdmCandidateSearchCriteriaBuilderSvc.java

@@ -55,18 +55,17 @@ public class MdmCandidateSearchCriteriaBuilderSvc {
 
 		// If there are candidate search params, then make use of them, otherwise, search with only the filters.
 		if (resourceSearchParam != null) {
-			resourceSearchParam.iterator().forEachRemaining(searchParam -> {
+			for (String searchParam : resourceSearchParam) {
 				// to compare it to all known GOLDEN_RESOURCE objects, using the overlapping search parameters that they
 				// have.
 				List<String> valuesFromResourceForSearchParam =
 						myMdmSearchParamSvc.getValueFromResourceForSearchParam(theResource, searchParam);
-				if (!valuesFromResourceForSearchParam.isEmpty()) {
-					criteria.add(buildResourceMatchQuery(searchParam, valuesFromResourceForSearchParam));
+				if (valuesFromResourceForSearchParam.isEmpty()) {
+					// Don't search if some of the search parameters aren't present in the resource
+					return Optional.empty();
 				}
-			});
-			if (criteria.isEmpty()) {
-				// TODO GGG/KHS, re-evaluate whether we should early drop here.
-				return Optional.empty();
+
+				criteria.add(buildResourceMatchQuery(searchParam, valuesFromResourceForSearchParam));
 			}
 		}
 

hapi-fhir-jpaserver-mdm/src/test/java/ca/uhn/fhir/jpa/mdm/provider/MdmProviderBatchR4Test.java

@@ -99,6 +99,27 @@ public class MdmProviderBatchR4Test extends BaseLinkR4Test {
 		super.after();
 	}
 
+	protected void clearMdmLinks() {
+		// Override of super class.
+		//
+		// Each resource that needs to be cleared produces a separate work chunk in batch processing, owing to a loop
+		// in MdmGenerateRangeChunksStep. There are three resource types used in this test, so that means there are
+		// three work chunks created for finding GoldenResourceIds and deleting them.
+		//
+		// TestR4Config proscribes (via JpaBatch2Config/BaseBatch2Config) that there are 4 threads processing chunks.
+		// However, TestR4Config also proscribes that there is somewhere between 3 and 8 database connections available.
+		//
+		// Consequently, if we clear all resource types at once, we can end up with 3 threads processing a chunk each.
+		// Which would be fine, except LoadGoldenIdsStep requires 2 database connections - one to read data,
+		// and the second to create the clear step chunks based on that data. If TestR4Config rolls low and there
+		// are only three connections available, we risk a deadlock due to database connection exhaustion if we
+		// process all 3 resource types at once. (With 4 connections or more, one of the three chunks is guaranteed to
+		// be able to finish, thereby freeing resources for the other chunks to finish.)
+		clearMdmLinks("Medication");
+		clearMdmLinks("Practitioner");
+		clearMdmLinks("Patient");
+	}
+
 	@ParameterizedTest
 	@MethodSource("requestTypes")
 	public void testBatchRunOnAllMedications(ServletRequestDetails theSyncOrAsyncRequest) throws InterruptedException {

hapi-fhir-jpaserver-mdm/src/test/java/ca/uhn/fhir/jpa/mdm/svc/MdmCandidateSearchCriteriaBuilderSvcTest.java

@@ -97,4 +97,17 @@ public class MdmCandidateSearchCriteriaBuilderSvcTest extends BaseMdmR4Test {
 		assertEquals(true, result.isPresent());
 		assertThat(result).contains("Patient?active=true");
 	}
+
+	@Test
+	public void testNoSearchIfASearchParamIsMissing() {
+		Patient patient = new Patient();
+		HumanName humanName = patient.addName();
+		humanName.addGiven("Jose");
+		humanName.addGiven("Martin");
+		MdmResourceSearchParamJson searchParamJson = new MdmResourceSearchParamJson();
+		searchParamJson.addSearchParam("given");
+		searchParamJson.addSearchParam("family");
+		Optional<String> result = myMdmCandidateSearchCriteriaBuilderSvc.buildResourceQueryString("Patient", patient, Collections.emptyList(), searchParamJson);
+		assertFalse(result.isPresent());
+	}
 }

pom.xml

@@ -916,6 +916,11 @@
 			<name>Stefan Lindström</name>
 			<organization>Softhouse AB</organization>
 		</developer>
+    <developer>
+      <id>adriennesox</id>
+			<name>Adrienne Sox</name>
+			<organization>Galileo, Inc.</organization>
+    </developer>
 	</developers>
 
 	<licenses>