Allow constraints to be deleted by the migrator on H2 (#2002)

hapi-fhir-jpaserver-migrate/src/main/java/ca/uhn/fhir/jpa/migrate/taskdef/DropIndexTask.java

@@ -28,11 +28,16 @@ import org.apache.commons.lang3.builder.HashCodeBuilder;
 import org.intellij.lang.annotations.Language;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
+import org.springframework.jdbc.core.JdbcTemplate;
+import org.springframework.jdbc.core.RowMapperResultSetExtractor;
+import org.springframework.jdbc.core.SingleColumnRowMapper;
 
+import javax.sql.DataSource;
 import java.sql.SQLException;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
+import java.util.Objects;
 import java.util.Set;
 
 public class DropIndexTask extends BaseTableTask {
@@ -54,6 +59,52 @@ public class DropIndexTask extends BaseTableTask {
 
 	@Override
 	public void doExecute() throws SQLException {
+		/*
+		 * Derby and H2 both behave a bit weirdly if you create a unique constraint
+		 * using the @UniqueConstraint annotation in hibernate - They will create a
+		 * constraint with that name, but will then create a shadow index with a different
+		 * name, and it's that different name that gets reported when you query for the
+		 * list of indexes.
+		 *
+		 * For example, on H2 if you create a constraint named "IDX_FOO", the system
+		 * will create an index named "IDX_FOO_INDEX_A" and a constraint named "IDX_FOO".
+		 *
+		 * The following is a solution that uses appropriate native queries to detect
+		 * on the given platforms whether an index name actually corresponds to a
+		 * constraint, and delete that constraint.
+		 */
+
+		@Language("SQL") String findConstraintSql;
+		@Language("SQL") String dropConstraintSql;
+		if (getDriverType() == DriverTypeEnum.H2_EMBEDDED) {
+			findConstraintSql = "SELECT DISTINCT INDEX_NAME FROM INFORMATION_SCHEMA.INDEXES WHERE constraint_name = ? AND table_name = ?";
+			dropConstraintSql = "ALTER TABLE " + getTableName() + " DROP CONSTRAINT " + myIndexName;
+		} else if (getDriverType() == DriverTypeEnum.DERBY_EMBEDDED) {
+			findConstraintSql = "SELECT c.constraintname FROM sys.sysconstraints c, sys.systables t WHERE c.tableid = t.tableid AND c.constraintname = ? AND t.tablename = ?";
+			dropConstraintSql = "ALTER TABLE " + getTableName() + " DROP CONSTRAINT " + myIndexName;
+		} else {
+			findConstraintSql = null;
+			dropConstraintSql = null;
+		}
+
+		if (findConstraintSql != null) {
+			DataSource dataSource = Objects.requireNonNull(getConnectionProperties().getDataSource());
+			Boolean handled = getConnectionProperties().getTxTemplate().execute(t -> {
+				JdbcTemplate jdbcTemplate = new JdbcTemplate(dataSource);
+				RowMapperResultSetExtractor<String> resultSetExtractor = new RowMapperResultSetExtractor<>(new SingleColumnRowMapper<>(String.class));
+				List<String> outcome = jdbcTemplate.query(findConstraintSql, new Object[]{myIndexName, getTableName()}, resultSetExtractor);
+				assert outcome != null;
+				if (outcome.size() > 0) {
+					executeSql(getTableName(), dropConstraintSql);
+					return true;
+				}
+				return false;
+			});
+			if (Boolean.TRUE.equals(handled)) {
+				return;
+			}
+		}
+
 		Set<String> indexNames = JdbcUtils.getIndexNames(getConnectionProperties(), getTableName());
 
 		if (!indexNames.contains(myIndexName)) {

hapi-fhir-jpaserver-migrate/src/main/java/ca/uhn/fhir/jpa/migrate/tasks/HapiFhirJpaMigrationTasks.java

@@ -136,13 +136,20 @@ public class HapiFhirJpaMigrationTasks extends BaseMigrationTasks<VersionEnum> {
 		empiLink.addColumn("20200715.3", "NEW_PERSON").nullable().type(ColumnTypeEnum.BOOLEAN);
 		empiLink.addColumn("20200715.4", "VECTOR").nullable().type(ColumnTypeEnum.LONG);
 		empiLink.addColumn("20200715.5", "SCORE").nullable().type(ColumnTypeEnum.FLOAT);
+
+		init510_20200725();
+	}
+
+	protected void init510_20200725() {
+		// nothing
 	}
 
 	protected void init510_20200610() {
+		// nothing
 	}
 
 	protected void init510_20200706_to_20200714() {
-
+		// nothing
 	}
 
 	private void init501() { //20200514 - present

hapi-fhir-jpaserver-migrate/src/test/java/ca/uhn/fhir/jpa/migrate/taskdef/DropIndexTest.java

@@ -1,6 +1,7 @@
 package ca.uhn.fhir.jpa.migrate.taskdef;
 
 import ca.uhn.fhir.jpa.migrate.JdbcUtils;
+import org.hamcrest.Matchers;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.MethodSource;
@@ -10,6 +11,8 @@ import java.util.function.Supplier;
 
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.contains;
+import static org.hamcrest.Matchers.empty;
+import static org.hamcrest.Matchers.not;
 
 public class DropIndexTest extends BaseTest {
 
@@ -93,4 +96,23 @@ public class DropIndexTest extends BaseTest {
 		assertThat(JdbcUtils.getIndexNames(getConnectionProperties(), "SOMETABLE"), contains("IDX_DIFINDEX"));
 	}
 
+	@ParameterizedTest(name = "{index}: {0}")
+	@MethodSource("data")
+	public void testDropConstraintIndex(Supplier<TestDatabaseDetails> theTestDatabaseDetails) throws SQLException {
+		before(theTestDatabaseDetails);
+
+		executeSql("create table SOMETABLE (PID bigint not null, TEXTCOL varchar(255), TEXTCOL2 varchar(255))");
+		executeSql("alter table SOMETABLE add constraint IDX_DIFINDEX unique (TEXTCOL, TEXTCOL2)");
+
+		DropIndexTask task = new DropIndexTask("1", "1");
+		task.setDescription("Drop an index");
+		task.setIndexName("IDX_DIFINDEX");
+		task.setTableName("SOMETABLE");
+		getMigrator().addTask(task);
+
+		assertThat(JdbcUtils.getIndexNames(getConnectionProperties(), "SOMETABLE"), not(empty()));
+		getMigrator().migrate();
+		assertThat(JdbcUtils.getIndexNames(getConnectionProperties(), "SOMETABLE"), empty());
+	}
+
 }