diff --git a/mapper/orm/src/main/java/org/hibernate/search/mapper/orm/massindexing/impl/HibernateOrmMassIndexingContext.java b/mapper/orm/src/main/java/org/hibernate/search/mapper/orm/massindexing/impl/HibernateOrmMassIndexingContext.java
index 89bf5a65242..1f87d4dfa12 100644
--- a/mapper/orm/src/main/java/org/hibernate/search/mapper/orm/massindexing/impl/HibernateOrmMassIndexingContext.java
+++ b/mapper/orm/src/main/java/org/hibernate/search/mapper/orm/massindexing/impl/HibernateOrmMassIndexingContext.java
@@ -18,7 +18,6 @@
 import org.hibernate.engine.spi.SessionFactoryImplementor;
 import org.hibernate.engine.spi.SessionImplementor;
 import org.hibernate.engine.spi.SharedSessionContractImplementor;
-import org.hibernate.search.engine.backend.session.spi.DetachedBackendSessionContext;
 import org.hibernate.search.mapper.orm.loading.impl.HibernateOrmEntityLoadingStrategy;
 import org.hibernate.search.mapper.orm.loading.impl.HibernateOrmMassEntityLoader;
 import org.hibernate.search.mapper.orm.loading.impl.HibernateOrmMassIdentifierLoader;
@@ -41,8 +40,6 @@ public final class HibernateOrmMassIndexingContext
 		implements PojoMassIndexingContext, HibernateOrmMassLoadingOptions {
 	private final HibernateOrmMassIndexingMappingContext mappingContext;
 	private final HibernateOrmSessionTypeContextProvider typeContextProvider;
-	private final DetachedBackendSessionContext sessionContext;
-
 	private final Map<Class<?>, ConditionalExpression> conditionalExpressions = new HashMap<>();
 	private CacheMode cacheMode = CacheMode.IGNORE;
 	private Integer idLoadingTransactionTimeout;
@@ -51,11 +48,9 @@ public final class HibernateOrmMassIndexingContext
 	private long objectsLimit = 0; //means no limit at all
 
 	public HibernateOrmMassIndexingContext(HibernateOrmMassIndexingMappingContext mappingContext,
-			HibernateOrmSessionTypeContextProvider typeContextContainer,
-			DetachedBackendSessionContext sessionContext) {
+			HibernateOrmSessionTypeContextProvider typeContextContainer) {
 		this.mappingContext = mappingContext;
 		this.typeContextProvider = typeContextContainer;
-		this.sessionContext = sessionContext;
 	}
 
 	@Override
@@ -179,7 +174,7 @@ public PojoMassIdentifierLoader createIdentifierLoader(PojoMassIndexingIdentifie
 					typeContexts, conditionalExpression );
 			SharedSessionContractImplementor session = (SharedSessionContractImplementor) sessionFactory
 					.withStatelessOptions()
-					.tenantIdentifier( sessionContext.tenantIdentifier() )
+					.tenantIdentifier( context.tenantIdentifier() )
 					.openStatelessSession();
 			try {
 				PojoMassIdentifierSink<I> sink = context.createSink();
@@ -203,7 +198,7 @@ public PojoMassEntityLoader<I> createEntityLoader(PojoMassIndexingEntityLoadingC
 					typeContexts, conditionalExpression );
 			SessionImplementor session = (SessionImplementor) sessionFactory
 					.withOptions()
-					.tenantIdentifier( sessionContext.tenantIdentifier() )
+					.tenantIdentifier( context.tenantIdentifier() )
 					.openSession();
 			try {
 				session.setHibernateFlushMode( FlushMode.MANUAL );
diff --git a/mapper/orm/src/main/java/org/hibernate/search/mapper/orm/scope/SearchScope.java b/mapper/orm/src/main/java/org/hibernate/search/mapper/orm/scope/SearchScope.java
index 196219f1633..45cf2e46086 100644
--- a/mapper/orm/src/main/java/org/hibernate/search/mapper/orm/scope/SearchScope.java
+++ b/mapper/orm/src/main/java/org/hibernate/search/mapper/orm/scope/SearchScope.java
@@ -6,6 +6,7 @@
  */
 package org.hibernate.search.mapper.orm.scope;
 
+import java.util.Collection;
 import java.util.Set;
 import java.util.function.Function;
 
@@ -158,6 +159,19 @@ public interface SearchScope<E> {
 	 */
 	MassIndexer massIndexer(String tenantId);
 
+	/**
+	 * Create a {@link MassIndexer} for the indexes mapped to types in this scope, or to any of their sub-types.
+	 * <p>
+	 * This method works for both single- and multi-tenant applications.
+	 * If multi-tenancy is disabled, simply keep the list of tenants empty.
+	 * <p>
+	 * {@link MassIndexer} instances cannot be reused.
+	 *
+	 * @param tenantIds The tenants identifiers whose index content should be targeted. If empty, all tenants will be targeted.
+	 * @return A {@link MassIndexer}.
+	 */
+	MassIndexer massIndexer(Collection<String> tenantIds);
+
 	/**
 	 * @return A set containing one {@link SearchIndexedEntity} for each indexed entity in this scope.
 	 */
diff --git a/mapper/orm/src/main/java/org/hibernate/search/mapper/orm/scope/impl/SearchScopeImpl.java b/mapper/orm/src/main/java/org/hibernate/search/mapper/orm/scope/impl/SearchScopeImpl.java
index 31a638ef8ba..898000dc12f 100644
--- a/mapper/orm/src/main/java/org/hibernate/search/mapper/orm/scope/impl/SearchScopeImpl.java
+++ b/mapper/orm/src/main/java/org/hibernate/search/mapper/orm/scope/impl/SearchScopeImpl.java
@@ -6,7 +6,11 @@
  */
 package org.hibernate.search.mapper.orm.scope.impl;
 
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
 import java.util.Set;
+import java.util.stream.Collectors;
 
 import org.hibernate.search.engine.backend.scope.IndexScopeExtension;
 import org.hibernate.search.engine.backend.session.spi.DetachedBackendSessionContext;
@@ -18,9 +22,9 @@
 import org.hibernate.search.mapper.orm.common.EntityReference;
 import org.hibernate.search.mapper.orm.entity.SearchIndexedEntity;
 import org.hibernate.search.mapper.orm.loading.impl.HibernateOrmSelectionLoadingContext;
-import org.hibernate.search.mapper.orm.massindexing.impl.HibernateOrmMassIndexingContext;
 import org.hibernate.search.mapper.orm.massindexing.MassIndexer;
 import org.hibernate.search.mapper.orm.massindexing.impl.HibernateOrmMassIndexer;
+import org.hibernate.search.mapper.orm.massindexing.impl.HibernateOrmMassIndexingContext;
 import org.hibernate.search.mapper.orm.schema.management.SearchSchemaManager;
 import org.hibernate.search.mapper.orm.schema.management.impl.SearchSchemaManagerImpl;
 import org.hibernate.search.mapper.orm.scope.SearchScope;
@@ -89,20 +93,30 @@ public SearchWorkspace workspace(DetachedBackendSessionContext detachedSessionCo
 
 	@Override
 	public MassIndexer massIndexer() {
-		return massIndexer( (String) null );
+		return massIndexer( Collections.<String>emptyList() );
 	}
 
 	@Override
 	public MassIndexer massIndexer(String tenantId) {
-		return massIndexer( DetachedBackendSessionContext.of( mappingContext, tenantId ) );
+		return massIndexer( Collections.singletonList( tenantId ) );
+	}
+
+	@Override
+	public MassIndexer massIndexer(Collection<String> tenantIds) {
+		return massIndexer( tenantIds.isEmpty() ?
+				Collections.singletonList( DetachedBackendSessionContext.of( mappingContext, null ) ) :
+				tenantIds.stream()
+						.map( id -> DetachedBackendSessionContext.of( mappingContext, id ) )
+						.collect( Collectors.toList() )
+		);
 	}
 
-	public MassIndexer massIndexer(DetachedBackendSessionContext detachedSessionContext) {
+	public MassIndexer massIndexer(List<DetachedBackendSessionContext> detachedSessionContexts) {
 		HibernateOrmMassIndexingContext massIndexingContext = new HibernateOrmMassIndexingContext( mappingContext,
-						mappingContext.typeContextProvider(), detachedSessionContext );
+						mappingContext.typeContextProvider() );
 
 		PojoMassIndexer massIndexerDelegate = delegate
-				.massIndexer( massIndexingContext, detachedSessionContext );
+				.massIndexer( massIndexingContext, detachedSessionContexts );
 
 		return new HibernateOrmMassIndexer( massIndexerDelegate, massIndexingContext );
 	}
diff --git a/mapper/orm/src/main/java/org/hibernate/search/mapper/orm/session/impl/HibernateOrmSearchSession.java b/mapper/orm/src/main/java/org/hibernate/search/mapper/orm/session/impl/HibernateOrmSearchSession.java
index 9932bdc4e71..19ea9067efd 100644
--- a/mapper/orm/src/main/java/org/hibernate/search/mapper/orm/session/impl/HibernateOrmSearchSession.java
+++ b/mapper/orm/src/main/java/org/hibernate/search/mapper/orm/session/impl/HibernateOrmSearchSession.java
@@ -7,6 +7,7 @@
 package org.hibernate.search.mapper.orm.session.impl;
 
 import java.lang.invoke.MethodHandles;
+import java.util.Arrays;
 import java.util.Collection;
 import javax.persistence.EntityManager;
 import javax.transaction.Synchronization;
@@ -154,7 +155,7 @@ public SearchWorkspace workspace(Collection<? extends Class<?>> types) {
 
 	@Override
 	public MassIndexer massIndexer(Collection<? extends Class<?>> types) {
-		return scope( types ).massIndexer( DetachedBackendSessionContext.of( this ) );
+		return scope( types ).massIndexer( Arrays.asList( DetachedBackendSessionContext.of( this ) ) );
 	}
 
 	@Override
diff --git a/mapper/pojo-base/src/main/java/org/hibernate/search/mapper/pojo/massindexing/impl/PojoDefaultMassIndexer.java b/mapper/pojo-base/src/main/java/org/hibernate/search/mapper/pojo/massindexing/impl/PojoDefaultMassIndexer.java
index 44c25113bcb..308e6f92331 100644
--- a/mapper/pojo-base/src/main/java/org/hibernate/search/mapper/pojo/massindexing/impl/PojoDefaultMassIndexer.java
+++ b/mapper/pojo-base/src/main/java/org/hibernate/search/mapper/pojo/massindexing/impl/PojoDefaultMassIndexer.java
@@ -7,6 +7,7 @@
 package org.hibernate.search.mapper.pojo.massindexing.impl;
 
 import java.lang.invoke.MethodHandles;
+import java.util.Collection;
 import java.util.List;
 import java.util.Set;
 import java.util.concurrent.CompletableFuture;
@@ -16,12 +17,11 @@
 import org.hibernate.search.mapper.pojo.logging.impl.Log;
 import org.hibernate.search.mapper.pojo.massindexing.MassIndexingFailureHandler;
 import org.hibernate.search.mapper.pojo.massindexing.MassIndexingMonitor;
+import org.hibernate.search.mapper.pojo.massindexing.spi.PojoMassIndexer;
 import org.hibernate.search.mapper.pojo.massindexing.spi.PojoMassIndexingContext;
 import org.hibernate.search.mapper.pojo.massindexing.spi.PojoMassIndexingMappingContext;
-import org.hibernate.search.mapper.pojo.massindexing.spi.PojoMassIndexer;
-
 import org.hibernate.search.mapper.pojo.schema.management.spi.PojoScopeSchemaManager;
-import org.hibernate.search.mapper.pojo.work.spi.PojoScopeWorkspace;
+import org.hibernate.search.mapper.pojo.scope.spi.PojoScopeDelegate;
 import org.hibernate.search.util.common.impl.Futures;
 import org.hibernate.search.util.common.logging.impl.LoggerFactory;
 
@@ -41,8 +41,8 @@ public class PojoDefaultMassIndexer implements PojoMassIndexer {
 	private final PojoMassIndexingTypeContextProvider typeContextProvider;
 	private final Set<? extends PojoMassIndexingIndexedTypeContext<?>> targetedIndexedTypes;
 	private final PojoScopeSchemaManager scopeSchemaManager;
-	private final DetachedBackendSessionContext detachedSession;
-	private final PojoScopeWorkspace scopeWorkspace;
+	private final Collection<DetachedBackendSessionContext> detachedSessions;
+	private final PojoScopeDelegate<?, ?, ?> pojoScopeDelegate;
 
 	// default settings defined here:
 	private int typesToIndexInParallel = 1;
@@ -60,15 +60,15 @@ public PojoDefaultMassIndexer(PojoMassIndexingContext indexingContext,
 			PojoMassIndexingTypeContextProvider typeContextProvider,
 			Set<? extends PojoMassIndexingIndexedTypeContext<?>> targetedIndexedTypes,
 			PojoScopeSchemaManager scopeSchemaManager,
-			DetachedBackendSessionContext detachedSession,
-			PojoScopeWorkspace scopeWorkspace) {
+			Collection<DetachedBackendSessionContext> detachedSessions,
+			PojoScopeDelegate<?, ?, ?> pojoScopeDelegate) {
 		this.indexingContext = indexingContext;
 		this.mappingContext = mappingContext;
 		this.typeContextProvider = typeContextProvider;
 		this.targetedIndexedTypes = targetedIndexedTypes;
 		this.scopeSchemaManager = scopeSchemaManager;
-		this.detachedSession = detachedSession;
-		this.scopeWorkspace = scopeWorkspace;
+		this.detachedSessions = detachedSessions;
+		this.pojoScopeDelegate = pojoScopeDelegate;
 	}
 
 	@Override
@@ -169,7 +169,8 @@ private PojoMassIndexingBatchCoordinator createCoordinator() {
 		return new PojoMassIndexingBatchCoordinator(
 				mappingContext,
 				notifier,
-				typeGroupsToIndex, scopeSchemaManager, detachedSession, scopeWorkspace,
+				typeGroupsToIndex, scopeSchemaManager,
+				detachedSessions, pojoScopeDelegate,
 				typesToIndexInParallel, documentBuilderThreads,
 				mergeSegmentsOnFinish,
 				// false by default:
diff --git a/mapper/pojo-base/src/main/java/org/hibernate/search/mapper/pojo/massindexing/impl/PojoMassIndexingBatchCoordinator.java b/mapper/pojo-base/src/main/java/org/hibernate/search/mapper/pojo/massindexing/impl/PojoMassIndexingBatchCoordinator.java
index 7cf8f6bdbc3..bf7d25a146b 100644
--- a/mapper/pojo-base/src/main/java/org/hibernate/search/mapper/pojo/massindexing/impl/PojoMassIndexingBatchCoordinator.java
+++ b/mapper/pojo-base/src/main/java/org/hibernate/search/mapper/pojo/massindexing/impl/PojoMassIndexingBatchCoordinator.java
@@ -7,11 +7,13 @@
 package org.hibernate.search.mapper.pojo.massindexing.impl;
 
 import java.util.ArrayList;
+import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Future;
+import java.util.function.Function;
 
 import org.hibernate.search.engine.backend.session.spi.DetachedBackendSessionContext;
 import org.hibernate.search.engine.backend.work.execution.OperationSubmitter;
@@ -20,6 +22,7 @@
 import org.hibernate.search.mapper.pojo.massindexing.spi.PojoMassIndexingMappingContext;
 import org.hibernate.search.mapper.pojo.reporting.impl.PojoEventContextMessages;
 import org.hibernate.search.mapper.pojo.schema.management.spi.PojoScopeSchemaManager;
+import org.hibernate.search.mapper.pojo.scope.spi.PojoScopeDelegate;
 import org.hibernate.search.mapper.pojo.work.spi.PojoScopeWorkspace;
 import org.hibernate.search.util.common.AssertionFailure;
 import org.hibernate.search.util.common.impl.Closer;
@@ -38,9 +41,8 @@ public class PojoMassIndexingBatchCoordinator extends PojoMassIndexingFailureHan
 	private final List<PojoMassIndexingIndexedTypeGroup<?>> typeGroupsToIndex;
 
 	private final PojoScopeSchemaManager scopeSchemaManager;
-	private final DetachedBackendSessionContext detachedSession;
-	private final PojoScopeWorkspace scopeWorkspace;
-
+	private final Collection<DetachedBackendSessionContext> detachedSessions;
+	private final PojoScopeDelegate<?, ?, ?> pojoScopeDelegate;
 	private final int typesToIndexInParallel;
 	private final int documentBuilderThreads;
 	private final boolean mergeSegmentsOnFinish;
@@ -49,14 +51,15 @@ public class PojoMassIndexingBatchCoordinator extends PojoMassIndexingFailureHan
 	private final boolean mergeSegmentsAfterPurge;
 
 	private final List<CompletableFuture<?>> indexingFutures = new ArrayList<>();
-	private PojoMassIndexerAgent agent;
+
+	private final Collection<SessionContext> coordinatorContexts = new ArrayList<>();
 
 	public PojoMassIndexingBatchCoordinator(PojoMassIndexingMappingContext mappingContext,
 			PojoMassIndexingNotifier notifier,
 			List<PojoMassIndexingIndexedTypeGroup<?>> typeGroupsToIndex,
 			PojoScopeSchemaManager scopeSchemaManager,
-			DetachedBackendSessionContext detachedSession,
-			PojoScopeWorkspace scopeWorkspace,
+			Collection<DetachedBackendSessionContext> detachedSessions,
+			PojoScopeDelegate<?, ?, ?> pojoScopeDelegate,
 			int typesToIndexInParallel, int documentBuilderThreads, boolean mergeSegmentsOnFinish,
 			boolean dropAndCreateSchemaOnStart, boolean purgeAtStart, boolean mergeSegmentsAfterPurge) {
 		super( notifier );
@@ -64,8 +67,8 @@ public PojoMassIndexingBatchCoordinator(PojoMassIndexingMappingContext mappingCo
 		this.typeGroupsToIndex = typeGroupsToIndex;
 
 		this.scopeSchemaManager = scopeSchemaManager;
-		this.detachedSession = detachedSession;
-		this.scopeWorkspace = scopeWorkspace;
+		this.detachedSessions = detachedSessions;
+		this.pojoScopeDelegate = pojoScopeDelegate;
 		this.typesToIndexInParallel = typesToIndexInParallel;
 		this.documentBuilderThreads = documentBuilderThreads;
 		this.mergeSegmentsOnFinish = mergeSegmentsOnFinish;
@@ -96,12 +99,25 @@ public void runWithFailureHandler() throws InterruptedException {
 	 * Operations to do before the multiple-threads start indexing
 	 */
 	private void beforeBatch() throws InterruptedException {
-		// Create an agent to suspend concurrent indexing
-		agent = mappingContext.createMassIndexerAgent(
-				new PojoMassIndexerAgentCreateContextImpl( mappingContext, detachedSession.tenantIdentifier() )
-		);
+		// Prepare the contexts first. These will be used for all batch related work:
+		for ( DetachedBackendSessionContext detachedSession : detachedSessions ) {
+			coordinatorContexts.add(
+					new SessionContext(
+							// Create an agent to suspend concurrent indexing
+							mappingContext.createMassIndexerAgent(
+									new PojoMassIndexerAgentCreateContextImpl( mappingContext, detachedSession.tenantIdentifier() )
+							),
+							pojoScopeDelegate.workspace( detachedSession ),
+							detachedSession
+					)
+			);
+		}
+
 		// Start the agent and wait until concurrent indexing actually gets suspended
-		Futures.unwrappedExceptionGet( agent.start() );
+		applyToAllContexts(
+				c -> CompletableFuture.supplyAsync( () -> c.agent().start() )
+		);
+
 
 		if ( dropAndCreateSchemaOnStart ) {
 			RootFailureCollector failureCollector = new RootFailureCollector(
@@ -112,9 +128,17 @@ private void beforeBatch() throws InterruptedException {
 		}
 
 		if ( purgeAtStart ) {
-			Futures.unwrappedExceptionGet( scopeWorkspace.purge( Collections.emptySet(), OperationSubmitter.BLOCKING ) );
+			applyToAllContexts(
+					context -> context.scopeWorkspace().purge( Collections.emptySet(), OperationSubmitter.BLOCKING )
+			);
 			if ( mergeSegmentsAfterPurge ) {
-				Futures.unwrappedExceptionGet( scopeWorkspace.mergeSegments( OperationSubmitter.BLOCKING ) );
+				// TODO: HSEARCH-4767 Note this only works fine as long as we have only a discriminator-based multitenancy.
+				// We deliberately are targeting a single context as the underlying operation at this point is not tenant dependent
+				// and calling it for multiple tenants would just request doing the same work.
+				Futures.unwrappedExceptionGet(
+						coordinatorContexts.iterator().next()
+								.scopeWorkspace().mergeSegments( OperationSubmitter.BLOCKING )
+				);
 			}
 		}
 	}
@@ -131,7 +155,9 @@ private void doBatchWork() throws InterruptedException {
 						PojoMassIndexingBatchIndexingWorkspace.THREAD_NAME_PREFIX + "Workspace" );
 
 		for ( PojoMassIndexingIndexedTypeGroup<?> typeGroup : typeGroupsToIndex ) {
-			indexingFutures.add( Futures.runAsync( createBatchIndexingWorkspace( typeGroup ), executor ) );
+			for ( SessionContext context : coordinatorContexts ) {
+				indexingFutures.add( Futures.runAsync( createBatchIndexingWorkspace( typeGroup, context ), executor ) );
+			}
 		}
 		executor.shutdown();
 
@@ -142,11 +168,13 @@ private void doBatchWork() throws InterruptedException {
 	}
 
 	private <E> PojoMassIndexingBatchIndexingWorkspace<E, ?> createBatchIndexingWorkspace(
-			PojoMassIndexingIndexedTypeGroup<E> typeGroup) {
+			PojoMassIndexingIndexedTypeGroup<E> typeGroup, SessionContext context) {
 		return new PojoMassIndexingBatchIndexingWorkspace<>(
 				mappingContext, getNotifier(), typeGroup,
 				typeGroup.loadingStrategy(),
-				documentBuilderThreads );
+				documentBuilderThreads,
+				context.sessionContext().tenantIdentifier()
+		);
 	}
 
 	/**
@@ -154,17 +182,28 @@ mappingContext, getNotifier(), typeGroup,
 	 */
 	private void afterBatch() throws InterruptedException {
 		if ( mergeSegmentsOnFinish ) {
-			Futures.unwrappedExceptionGet( scopeWorkspace.mergeSegments( OperationSubmitter.BLOCKING ) );
+			// TODO: HSEARCH-4767 Note this only works fine as long as we have only a discriminator-based multitenancy.
+			// We deliberately are targeting a single context as the underlying operation at this point is not tenant dependent
+			// and calling it for multiple tenants would just request doing the same work.
+			Futures.unwrappedExceptionGet( coordinatorContexts.iterator().next()
+					.scopeWorkspace().mergeSegments( OperationSubmitter.BLOCKING )
+			);
 		}
 		flushAndRefresh();
-		Futures.unwrappedExceptionGet( agent.preStop() );
-		agent.stop();
-		agent = null;
+		applyToAllContexts(
+				context -> context.agent().preStop()
+						.thenRun( () -> context.agent().stop() )
+		);
+		coordinatorContexts.clear();
 	}
 
 	private void flushAndRefresh() throws InterruptedException {
-		Futures.unwrappedExceptionGet( scopeWorkspace.flush( OperationSubmitter.BLOCKING ) );
-		Futures.unwrappedExceptionGet( scopeWorkspace.refresh( OperationSubmitter.BLOCKING ) );
+		// TODO: HSEARCH-4767 Note this only works fine as long as we have only a discriminator-based multitenancy.
+		// We deliberately are targeting a single context as the underlying operation at this point is not tenant dependent
+		// and calling it for multiple tenants would just request doing the same work.
+		SessionContext context = coordinatorContexts.iterator().next();
+		Futures.unwrappedExceptionGet( context.scopeWorkspace().flush( OperationSubmitter.BLOCKING ) );
+		Futures.unwrappedExceptionGet( context.scopeWorkspace().refresh( OperationSubmitter.BLOCKING ) );
 	}
 
 	@Override
@@ -174,8 +213,8 @@ protected void cleanUpOnInterruption() throws InterruptedException {
 			// Indexing performed before the exception must still be committed,
 			// in order to leave the index in a consistent state
 			closer.push( PojoMassIndexingBatchCoordinator::flushAndRefresh, this );
-			closer.push( PojoMassIndexerAgent::stop, agent );
-			agent = null;
+			closer.pushAll( PojoMassIndexerAgent::stop, coordinatorContexts, SessionContext::agent );
+			coordinatorContexts.clear();
 		}
 	}
 
@@ -183,8 +222,8 @@ protected void cleanUpOnInterruption() throws InterruptedException {
 	protected void cleanUpOnFailure() {
 		try ( Closer<RuntimeException> closer = new Closer<>() ) {
 			closer.pushAll( this::cancelPendingTask, indexingFutures );
-			closer.push( PojoMassIndexerAgent::stop, agent );
-			agent = null;
+			closer.pushAll( PojoMassIndexerAgent::stop, coordinatorContexts, SessionContext::agent );
+			coordinatorContexts.clear();
 		}
 	}
 
@@ -212,4 +251,38 @@ protected void notifyFailure(RuntimeException exception) {
 		getNotifier().reportIndexingCompleted();
 	}
 
+	public static class SessionContext {
+		private final PojoMassIndexerAgent agent;
+		private final PojoScopeWorkspace scopeWorkspace;
+		private final DetachedBackendSessionContext sessionContext;
+
+		public SessionContext(PojoMassIndexerAgent agent, PojoScopeWorkspace scopeWorkspace, DetachedBackendSessionContext sessionContext) {
+			this.agent = agent;
+			this.scopeWorkspace = scopeWorkspace;
+			this.sessionContext = sessionContext;
+		}
+
+		public PojoMassIndexerAgent agent() {
+			return agent;
+		}
+
+		public PojoScopeWorkspace scopeWorkspace() {
+			return scopeWorkspace;
+		}
+
+		public DetachedBackendSessionContext sessionContext() {
+			return sessionContext;
+		}
+	}
+
+	private void applyToAllContexts(Function<SessionContext, CompletableFuture<?>> operation) throws InterruptedException {
+		Futures.unwrappedExceptionGet(
+				CompletableFuture.allOf(
+						coordinatorContexts.stream()
+								.map( c -> operation.apply( c ) )
+								.toArray( CompletableFuture[]::new )
+				)
+		);
+	}
+
 }
diff --git a/mapper/pojo-base/src/main/java/org/hibernate/search/mapper/pojo/massindexing/impl/PojoMassIndexingBatchIndexingWorkspace.java b/mapper/pojo-base/src/main/java/org/hibernate/search/mapper/pojo/massindexing/impl/PojoMassIndexingBatchIndexingWorkspace.java
index aa9d65db7a9..1376c577279 100644
--- a/mapper/pojo-base/src/main/java/org/hibernate/search/mapper/pojo/massindexing/impl/PojoMassIndexingBatchIndexingWorkspace.java
+++ b/mapper/pojo-base/src/main/java/org/hibernate/search/mapper/pojo/massindexing/impl/PojoMassIndexingBatchIndexingWorkspace.java
@@ -41,17 +41,19 @@ public class PojoMassIndexingBatchIndexingWorkspace<E, I> extends PojoMassIndexi
 	private final PojoMassIndexingLoadingStrategy<E, I> loadingStrategy;
 
 	private final int entityExtractingThreads;
+	private final String tenantId;
 
 	PojoMassIndexingBatchIndexingWorkspace(PojoMassIndexingMappingContext mappingContext,
 			PojoMassIndexingNotifier notifier,
 			PojoMassIndexingIndexedTypeGroup<E> typeGroup,
 			PojoMassIndexingLoadingStrategy<E, I> loadingStrategy,
-			int entityExtractingThreads) {
+			int entityExtractingThreads, String tenantId) {
 		super( notifier );
 		this.mappingContext = mappingContext;
 		this.typeGroup = typeGroup;
 		this.loadingStrategy = loadingStrategy;
 		this.entityExtractingThreads = entityExtractingThreads;
+		this.tenantId = tenantId;
 	}
 
 	@Override
@@ -95,7 +97,8 @@ private void cancelPendingTasks() {
 
 	private void startProducingPrimaryKeys(PojoProducerConsumerQueue<List<I>> identifierQueue) {
 		final Runnable runnable = new PojoMassIndexingEntityIdentifierLoadingRunnable<>( getNotifier(), typeGroup,
-				loadingStrategy, identifierQueue );
+				loadingStrategy, identifierQueue, tenantId
+		);
 		//execIdentifiersLoader has size 1 and is not configurable: ensures the list is consistent as produced by one transaction
 		final ThreadPoolExecutor identifierProducingExecutor = mappingContext.threadPoolProvider().newFixedThreadPool(
 				1,
@@ -111,7 +114,8 @@ private void startProducingPrimaryKeys(PojoProducerConsumerQueue<List<I>> identi
 
 	private void startIndexing(PojoProducerConsumerQueue<List<I>> identifierQueue) {
 		final Runnable runnable = new PojoMassIndexingEntityLoadingRunnable<>( getNotifier(), typeGroup,
-				loadingStrategy, identifierQueue );
+				loadingStrategy, identifierQueue, tenantId
+		);
 		final ThreadPoolExecutor indexingExecutor = mappingContext.threadPoolProvider().newFixedThreadPool(
 				entityExtractingThreads,
 				THREAD_NAME_PREFIX + typeGroup.notifiedGroupName() + " - Entity loading"
diff --git a/mapper/pojo-base/src/main/java/org/hibernate/search/mapper/pojo/massindexing/impl/PojoMassIndexingEntityIdentifierLoadingRunnable.java b/mapper/pojo-base/src/main/java/org/hibernate/search/mapper/pojo/massindexing/impl/PojoMassIndexingEntityIdentifierLoadingRunnable.java
index 119045e8445..fb98a2b3975 100644
--- a/mapper/pojo-base/src/main/java/org/hibernate/search/mapper/pojo/massindexing/impl/PojoMassIndexingEntityIdentifierLoadingRunnable.java
+++ b/mapper/pojo-base/src/main/java/org/hibernate/search/mapper/pojo/massindexing/impl/PojoMassIndexingEntityIdentifierLoadingRunnable.java
@@ -27,15 +27,17 @@ public class PojoMassIndexingEntityIdentifierLoadingRunnable<E, I>
 	private final PojoMassIndexingIndexedTypeGroup<E> typeGroup;
 	private final PojoMassIndexingLoadingStrategy<E, I> loadingStrategy;
 	private final PojoProducerConsumerQueue<List<I>> identifierQueue;
+	private final String tenantId;
 
 	public PojoMassIndexingEntityIdentifierLoadingRunnable(PojoMassIndexingNotifier notifier,
 			PojoMassIndexingIndexedTypeGroup<E> typeGroup,
 			PojoMassIndexingLoadingStrategy<E, I> loadingStrategy,
-			PojoProducerConsumerQueue<List<I>> identifierQueue) {
+			PojoProducerConsumerQueue<List<I>> identifierQueue, String tenantId) {
 		super( notifier );
 		this.loadingStrategy = loadingStrategy;
 		this.typeGroup = typeGroup;
 		this.identifierQueue = identifierQueue;
+		this.tenantId = tenantId;
 	}
 
 	@Override
@@ -97,5 +99,10 @@ public void complete() {
 				}
 			};
 		}
+
+		@Override
+		public String tenantIdentifier() {
+			return tenantId;
+		}
 	}
 }
diff --git a/mapper/pojo-base/src/main/java/org/hibernate/search/mapper/pojo/massindexing/impl/PojoMassIndexingEntityLoadingRunnable.java b/mapper/pojo-base/src/main/java/org/hibernate/search/mapper/pojo/massindexing/impl/PojoMassIndexingEntityLoadingRunnable.java
index 9cc9fdcde7f..59ec6b82d19 100644
--- a/mapper/pojo-base/src/main/java/org/hibernate/search/mapper/pojo/massindexing/impl/PojoMassIndexingEntityLoadingRunnable.java
+++ b/mapper/pojo-base/src/main/java/org/hibernate/search/mapper/pojo/massindexing/impl/PojoMassIndexingEntityLoadingRunnable.java
@@ -36,15 +36,18 @@ public class PojoMassIndexingEntityLoadingRunnable<E, I>
 	private final PojoMassIndexingIndexedTypeGroup<E> typeGroup;
 	private final PojoMassIndexingLoadingStrategy<E, I> loadingStrategy;
 	private final PojoProducerConsumerQueue<List<I>> identifierQueue;
+	private final String tenantId;
 
 	protected PojoMassIndexingEntityLoadingRunnable(PojoMassIndexingNotifier notifier,
 			PojoMassIndexingIndexedTypeGroup<E> typeGroup,
 			PojoMassIndexingLoadingStrategy<E, I> loadingStrategy,
-			PojoProducerConsumerQueue<List<I>> identifierQueue) {
+			PojoProducerConsumerQueue<List<I>> identifierQueue,
+			String tenantId) {
 		super( notifier );
 		this.typeGroup = typeGroup;
 		this.loadingStrategy = loadingStrategy;
 		this.identifierQueue = identifierQueue;
+		this.tenantId = tenantId;
 	}
 
 	@Override
@@ -131,6 +134,11 @@ public void accept(List<? extends E> batch) throws InterruptedException {
 			};
 		}
 
+		@Override
+		public String tenantIdentifier() {
+			return tenantId;
+		}
+
 		public void waitForLastBatches() throws InterruptedException {
 			for ( IndexingBatch batch : batches ) {
 				batch.waitForIndexingEndAndReport();
diff --git a/mapper/pojo-base/src/main/java/org/hibernate/search/mapper/pojo/massindexing/spi/PojoMassIndexingEntityLoadingContext.java b/mapper/pojo-base/src/main/java/org/hibernate/search/mapper/pojo/massindexing/spi/PojoMassIndexingEntityLoadingContext.java
index e7ec998f7f7..94cb8d5109b 100644
--- a/mapper/pojo-base/src/main/java/org/hibernate/search/mapper/pojo/massindexing/spi/PojoMassIndexingEntityLoadingContext.java
+++ b/mapper/pojo-base/src/main/java/org/hibernate/search/mapper/pojo/massindexing/spi/PojoMassIndexingEntityLoadingContext.java
@@ -29,4 +29,9 @@ public interface PojoMassIndexingEntityLoadingContext<E> {
 	 */
 	PojoMassEntitySink<E> createSink(PojoMassIndexingSessionContext sessionContext);
 
+	/**
+	 * @return The tenant identifier to use ({@code null} if none).
+	 */
+	String tenantIdentifier();
+
 }
diff --git a/mapper/pojo-base/src/main/java/org/hibernate/search/mapper/pojo/massindexing/spi/PojoMassIndexingIdentifierLoadingContext.java b/mapper/pojo-base/src/main/java/org/hibernate/search/mapper/pojo/massindexing/spi/PojoMassIndexingIdentifierLoadingContext.java
index 473824bcd91..3e799ea4b6a 100644
--- a/mapper/pojo-base/src/main/java/org/hibernate/search/mapper/pojo/massindexing/spi/PojoMassIndexingIdentifierLoadingContext.java
+++ b/mapper/pojo-base/src/main/java/org/hibernate/search/mapper/pojo/massindexing/spi/PojoMassIndexingIdentifierLoadingContext.java
@@ -29,4 +29,8 @@ public interface PojoMassIndexingIdentifierLoadingContext<E, I> {
 	 */
 	PojoMassIdentifierSink<I> createSink();
 
+	/**
+	 * @return The tenant identifier to use ({@code null} if none).
+	 */
+	String tenantIdentifier();
 }
diff --git a/mapper/pojo-base/src/main/java/org/hibernate/search/mapper/pojo/scope/impl/PojoScopeDelegateImpl.java b/mapper/pojo-base/src/main/java/org/hibernate/search/mapper/pojo/scope/impl/PojoScopeDelegateImpl.java
index 8b2a5cabd98..d162cbd9d43 100644
--- a/mapper/pojo-base/src/main/java/org/hibernate/search/mapper/pojo/scope/impl/PojoScopeDelegateImpl.java
+++ b/mapper/pojo-base/src/main/java/org/hibernate/search/mapper/pojo/scope/impl/PojoScopeDelegateImpl.java
@@ -154,9 +154,9 @@ public PojoScopeSchemaManager schemaManager() {
 	}
 
 	@Override
-	public PojoMassIndexer massIndexer(PojoMassIndexingContext context, DetachedBackendSessionContext detachedSession) {
+	public PojoMassIndexer massIndexer(PojoMassIndexingContext context, Collection<DetachedBackendSessionContext> detachedSessions) {
 		return new PojoDefaultMassIndexer( context, mappingContext, indexedTypeContextProvider, targetedTypeContexts,
-				schemaManager(), detachedSession, workspace( detachedSession ) );
+				schemaManager(), detachedSessions, this );
 	}
 
 	@Override
diff --git a/mapper/pojo-base/src/main/java/org/hibernate/search/mapper/pojo/scope/spi/PojoScopeDelegate.java b/mapper/pojo-base/src/main/java/org/hibernate/search/mapper/pojo/scope/spi/PojoScopeDelegate.java
index d6c61d89464..c4610b042a7 100644
--- a/mapper/pojo-base/src/main/java/org/hibernate/search/mapper/pojo/scope/spi/PojoScopeDelegate.java
+++ b/mapper/pojo-base/src/main/java/org/hibernate/search/mapper/pojo/scope/spi/PojoScopeDelegate.java
@@ -6,6 +6,7 @@
  */
 package org.hibernate.search.mapper.pojo.scope.spi;
 
+import java.util.Collection;
 import java.util.Set;
 
 import org.hibernate.search.engine.backend.common.spi.DocumentReferenceConverter;
@@ -52,7 +53,7 @@ public interface PojoScopeDelegate<R, E, C> {
 
 	PojoScopeSchemaManager schemaManager();
 
-	PojoMassIndexer massIndexer(PojoMassIndexingContext context, DetachedBackendSessionContext detachedSession);
+	PojoMassIndexer massIndexer(PojoMassIndexingContext context, Collection<DetachedBackendSessionContext> detachedSessions);
 
 	<T> T extension(IndexScopeExtension<T> extension);
 }
diff --git a/mapper/pojo-standalone/src/main/java/org/hibernate/search/mapper/pojo/standalone/loading/MassLoadingOptions.java b/mapper/pojo-standalone/src/main/java/org/hibernate/search/mapper/pojo/standalone/loading/MassLoadingOptions.java
index 62b1278a1b7..610b323176a 100644
--- a/mapper/pojo-standalone/src/main/java/org/hibernate/search/mapper/pojo/standalone/loading/MassLoadingOptions.java
+++ b/mapper/pojo-standalone/src/main/java/org/hibernate/search/mapper/pojo/standalone/loading/MassLoadingOptions.java
@@ -14,11 +14,6 @@
 @Incubating
 public interface MassLoadingOptions {
 
-	/**
-	 * @return The tenant identifier, or {@code null} for single-tenancy.
-	 */
-	String tenantIdentifier();
-
 	/**
 	 * @return How many entities to load and index in each batch.
 	 * Defines the maximum expected size of each list of IDs
diff --git a/mapper/pojo-standalone/src/main/java/org/hibernate/search/mapper/pojo/standalone/loading/SelectionLoadingOptions.java b/mapper/pojo-standalone/src/main/java/org/hibernate/search/mapper/pojo/standalone/loading/SelectionLoadingOptions.java
index 25a44726a91..b20b2028452 100644
--- a/mapper/pojo-standalone/src/main/java/org/hibernate/search/mapper/pojo/standalone/loading/SelectionLoadingOptions.java
+++ b/mapper/pojo-standalone/src/main/java/org/hibernate/search/mapper/pojo/standalone/loading/SelectionLoadingOptions.java
@@ -12,11 +12,6 @@
 @Incubating
 public interface SelectionLoadingOptions {
 
-	/**
-	 * @return The tenant identifier, or {@code null} for single-tenancy.
-	 */
-	String tenantIdentifier();
-
 	/**
 	 * Gets context previously passed to
 	 * {@link SelectionLoadingOptionsStep#context(Class, Object)}.
diff --git a/mapper/pojo-standalone/src/main/java/org/hibernate/search/mapper/pojo/standalone/loading/impl/StandalonePojoLoadingContext.java b/mapper/pojo-standalone/src/main/java/org/hibernate/search/mapper/pojo/standalone/loading/impl/StandalonePojoLoadingContext.java
index b0c87649bd3..268b73be3a8 100644
--- a/mapper/pojo-standalone/src/main/java/org/hibernate/search/mapper/pojo/standalone/loading/impl/StandalonePojoLoadingContext.java
+++ b/mapper/pojo-standalone/src/main/java/org/hibernate/search/mapper/pojo/standalone/loading/impl/StandalonePojoLoadingContext.java
@@ -13,7 +13,6 @@
 import java.util.Optional;
 import java.util.Set;
 
-import org.hibernate.search.engine.backend.session.spi.DetachedBackendSessionContext;
 import org.hibernate.search.mapper.pojo.standalone.loading.MassLoadingOptions;
 import org.hibernate.search.mapper.pojo.standalone.loading.MassLoadingStrategy;
 import org.hibernate.search.mapper.pojo.standalone.loading.SelectionLoadingOptions;
@@ -39,7 +38,6 @@ public final class StandalonePojoLoadingContext
 
 	private final StandalonePojoMassIndexingMappingContext mappingContext;
 	private final LoadingTypeContextProvider typeContextProvider;
-	private final DetachedBackendSessionContext sessionContext;
 
 	private int batchSize = 10;
 	private final Map<Class<?>, Object> contextData;
@@ -47,15 +45,9 @@ public final class StandalonePojoLoadingContext
 	private StandalonePojoLoadingContext(Builder builder) {
 		this.mappingContext = builder.mappingContext;
 		this.typeContextProvider = builder.typeContextProvider;
-		this.sessionContext = builder.sessionContext;
 		this.contextData = builder.contextData;
 	}
 
-	@Override
-	public String tenantIdentifier() {
-		return sessionContext.tenantIdentifier();
-	}
-
 	public void batchSize(int batchSize) {
 		if ( batchSize < 1 ) {
 			throw new IllegalArgumentException( "batchSize must be at least 1" );
@@ -113,20 +105,18 @@ public <T> Optional<PojoSelectionLoadingStrategy<? super T>> loadingStrategyOpti
 			throw log.entityLoadingStrategyNotRegistered( typeContext.typeIdentifier() );
 		}
 		return new StandalonePojoMassIndexingLoadingStrategy<>( mappingContext, typeContextProvider,
-				strategyOptional.get(), sessionContext, this );
+				strategyOptional.get(), this );
 	}
 
 	public static final class Builder implements StandalonePojoSelectionLoadingContextBuilder, SelectionLoadingOptionsStep {
 		private final StandalonePojoMassIndexingMappingContext mappingContext;
 		private final LoadingTypeContextProvider typeContextProvider;
-		private final DetachedBackendSessionContext sessionContext;
 		private final Map<Class<?>, Object> contextData = new HashMap<>();
 
 		public Builder(StandalonePojoMassIndexingMappingContext mappingContext,
-				LoadingTypeContextProvider typeContextProvider, DetachedBackendSessionContext sessionContext) {
+				LoadingTypeContextProvider typeContextProvider) {
 			this.mappingContext = mappingContext;
 			this.typeContextProvider = typeContextProvider;
-			this.sessionContext = sessionContext;
 		}
 
 		@Override
diff --git a/mapper/pojo-standalone/src/main/java/org/hibernate/search/mapper/pojo/standalone/mapping/impl/StandalonePojoMapping.java b/mapper/pojo-standalone/src/main/java/org/hibernate/search/mapper/pojo/standalone/mapping/impl/StandalonePojoMapping.java
index 27c5774515f..a9535afa968 100644
--- a/mapper/pojo-standalone/src/main/java/org/hibernate/search/mapper/pojo/standalone/mapping/impl/StandalonePojoMapping.java
+++ b/mapper/pojo-standalone/src/main/java/org/hibernate/search/mapper/pojo/standalone/mapping/impl/StandalonePojoMapping.java
@@ -18,7 +18,6 @@
 import org.hibernate.search.engine.backend.common.spi.EntityReferenceFactory;
 import org.hibernate.search.engine.backend.index.IndexManager;
 import org.hibernate.search.engine.backend.reporting.spi.BackendMappingHints;
-import org.hibernate.search.engine.backend.session.spi.DetachedBackendSessionContext;
 import org.hibernate.search.engine.common.spi.SearchIntegration;
 import org.hibernate.search.engine.mapper.mapping.spi.MappingPreStopContext;
 import org.hibernate.search.engine.mapper.mapping.spi.MappingStartContext;
@@ -201,8 +200,8 @@ public Backend backend(String backendName) {
 	}
 
 	@Override
-	public StandalonePojoLoadingContext.Builder loadingContextBuilder(DetachedBackendSessionContext sessionContext) {
-		return new StandalonePojoLoadingContext.Builder( this, typeContextContainer, sessionContext );
+	public StandalonePojoLoadingContext.Builder loadingContextBuilder() {
+		return new StandalonePojoLoadingContext.Builder( this, typeContextContainer );
 	}
 
 	@Override
@@ -212,8 +211,8 @@ public PojoMassIndexerAgent createMassIndexerAgent(PojoMassIndexerAgentCreateCon
 	}
 
 	@Override
-	public StandalonePojoMassIndexingSessionContext createSession(DetachedBackendSessionContext sessionContext) {
-		return createSessionBuilder().tenantId( sessionContext.tenantIdentifier() ).build();
+	public StandalonePojoMassIndexingSessionContext createSession(String tenantIdentifier) {
+		return createSessionBuilder().tenantId( tenantIdentifier ).build();
 	}
 
 	private SearchIntegration searchIntegration() {
diff --git a/mapper/pojo-standalone/src/main/java/org/hibernate/search/mapper/pojo/standalone/massindexing/impl/StandalonePojoMassIndexingLoadingStrategy.java b/mapper/pojo-standalone/src/main/java/org/hibernate/search/mapper/pojo/standalone/massindexing/impl/StandalonePojoMassIndexingLoadingStrategy.java
index bd7696702e7..59d26990822 100644
--- a/mapper/pojo-standalone/src/main/java/org/hibernate/search/mapper/pojo/standalone/massindexing/impl/StandalonePojoMassIndexingLoadingStrategy.java
+++ b/mapper/pojo-standalone/src/main/java/org/hibernate/search/mapper/pojo/standalone/massindexing/impl/StandalonePojoMassIndexingLoadingStrategy.java
@@ -6,7 +6,6 @@
  */
 package org.hibernate.search.mapper.pojo.standalone.massindexing.impl;
 
-import org.hibernate.search.engine.backend.session.spi.DetachedBackendSessionContext;
 import org.hibernate.search.mapper.pojo.standalone.loading.MassIdentifierSink;
 import org.hibernate.search.mapper.pojo.standalone.loading.MassLoadingOptions;
 import org.hibernate.search.mapper.pojo.standalone.loading.MassEntitySink;
@@ -30,17 +29,15 @@ public class StandalonePojoMassIndexingLoadingStrategy<E, I>
 	private final StandalonePojoMassIndexingMappingContext mappingContext;
 	private final LoadingTypeContextProvider typeContextProvider;
 	private final MassLoadingStrategy<E, I> delegate;
-	private final DetachedBackendSessionContext sessionContext;
 	private final MassLoadingOptions options;
 
 	public StandalonePojoMassIndexingLoadingStrategy(StandalonePojoMassIndexingMappingContext mappingContext,
 			LoadingTypeContextProvider typeContextProvider,
-			MassLoadingStrategy<E, I> delegate, DetachedBackendSessionContext sessionContext,
+			MassLoadingStrategy<E, I> delegate,
 			MassLoadingOptions options) {
 		this.mappingContext = mappingContext;
 		this.typeContextProvider = typeContextProvider;
 		this.delegate = delegate;
-		this.sessionContext = sessionContext;
 		this.options = options;
 	}
 
@@ -71,7 +68,7 @@ public PojoMassIdentifierLoader createIdentifierLoader(PojoMassIndexingIdentifie
 
 	@Override
 	public PojoMassEntityLoader<I> createEntityLoader(PojoMassIndexingEntityLoadingContext<E> context) {
-		StandalonePojoMassIndexingSessionContext session = mappingContext.createSession( sessionContext );
+		StandalonePojoMassIndexingSessionContext session = mappingContext.createSession( context.tenantIdentifier() );
 		try {
 			StandalonePojoLoadingTypeGroup<E> includedTypes = new StandalonePojoLoadingTypeGroup<>(
 					typeContextProvider, context.includedTypes(), mappingContext.runtimeIntrospector() );
diff --git a/mapper/pojo-standalone/src/main/java/org/hibernate/search/mapper/pojo/standalone/massindexing/impl/StandalonePojoMassIndexingMappingContext.java b/mapper/pojo-standalone/src/main/java/org/hibernate/search/mapper/pojo/standalone/massindexing/impl/StandalonePojoMassIndexingMappingContext.java
index 5081396654d..dd23d8a8e01 100644
--- a/mapper/pojo-standalone/src/main/java/org/hibernate/search/mapper/pojo/standalone/massindexing/impl/StandalonePojoMassIndexingMappingContext.java
+++ b/mapper/pojo-standalone/src/main/java/org/hibernate/search/mapper/pojo/standalone/massindexing/impl/StandalonePojoMassIndexingMappingContext.java
@@ -6,13 +6,12 @@
  */
 package org.hibernate.search.mapper.pojo.standalone.massindexing.impl;
 
-import org.hibernate.search.engine.backend.session.spi.DetachedBackendSessionContext;
 import org.hibernate.search.mapper.pojo.massindexing.spi.PojoMassIndexingMappingContext;
 import org.hibernate.search.mapper.pojo.model.spi.PojoRuntimeIntrospector;
 
 public interface StandalonePojoMassIndexingMappingContext extends PojoMassIndexingMappingContext {
 
-	StandalonePojoMassIndexingSessionContext createSession(DetachedBackendSessionContext sessionContext);
+	StandalonePojoMassIndexingSessionContext createSession(String tenantIdentifier);
 
 	PojoRuntimeIntrospector runtimeIntrospector();
 
diff --git a/mapper/pojo-standalone/src/main/java/org/hibernate/search/mapper/pojo/standalone/scope/SearchScope.java b/mapper/pojo-standalone/src/main/java/org/hibernate/search/mapper/pojo/standalone/scope/SearchScope.java
index 8f5e65dfd9b..d24735b6c86 100644
--- a/mapper/pojo-standalone/src/main/java/org/hibernate/search/mapper/pojo/standalone/scope/SearchScope.java
+++ b/mapper/pojo-standalone/src/main/java/org/hibernate/search/mapper/pojo/standalone/scope/SearchScope.java
@@ -6,6 +6,7 @@
  */
 package org.hibernate.search.mapper.pojo.standalone.scope;
 
+import java.util.Collection;
 import java.util.Set;
 import java.util.function.Function;
 
@@ -160,6 +161,19 @@ public interface SearchScope<E> {
 	 */
 	MassIndexer massIndexer(String tenantId);
 
+	/**
+	 * Create a {@link MassIndexer} for the indexes mapped to types in this scope, or to any of their sub-types.
+	 * <p>
+	 * This method works for both single- and multi-tenant applications.
+	 * If multi-tenancy is disabled, simply keep the list of tenants empty.
+	 * <p>
+	 * {@link MassIndexer} instances cannot be reused.
+	 *
+	 * @param tenantIds The tenants identifiers whose index content should be targeted. If empty, all tenants will be targeted.
+	 * @return A {@link MassIndexer}.
+	 */
+	MassIndexer massIndexer(Collection<String> tenantIds);
+
 	/**
 	 * @return A set containing one {@link SearchIndexedEntity} for each indexed entity in this scope.
 	 */
diff --git a/mapper/pojo-standalone/src/main/java/org/hibernate/search/mapper/pojo/standalone/scope/impl/SearchScopeImpl.java b/mapper/pojo-standalone/src/main/java/org/hibernate/search/mapper/pojo/standalone/scope/impl/SearchScopeImpl.java
index 6b83ef8a785..a5a8033d551 100644
--- a/mapper/pojo-standalone/src/main/java/org/hibernate/search/mapper/pojo/standalone/scope/impl/SearchScopeImpl.java
+++ b/mapper/pojo-standalone/src/main/java/org/hibernate/search/mapper/pojo/standalone/scope/impl/SearchScopeImpl.java
@@ -6,7 +6,11 @@
  */
 package org.hibernate.search.mapper.pojo.standalone.scope.impl;
 
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
 import java.util.Set;
+import java.util.stream.Collectors;
 
 import org.hibernate.search.engine.backend.common.spi.DocumentReferenceConverter;
 import org.hibernate.search.engine.backend.scope.IndexScopeExtension;
@@ -100,17 +104,27 @@ public <T> T extension(IndexScopeExtension<T> extension) {
 
 	@Override
 	public MassIndexer massIndexer() {
-		return massIndexer( (String) null );
+		return massIndexer( Collections.<String>emptyList() );
 	}
 
 	@Override
 	public MassIndexer massIndexer(String tenantId) {
-		return massIndexer( DetachedBackendSessionContext.of( mappingContext, tenantId ) );
+		return massIndexer( Collections.singletonList( tenantId ) );
 	}
 
-	public MassIndexer massIndexer(DetachedBackendSessionContext sessionContext) {
-		StandalonePojoLoadingContext context = mappingContext.loadingContextBuilder( sessionContext ).build();
-		PojoMassIndexer massIndexerDelegate = delegate.massIndexer( context, sessionContext );
+	@Override
+	public MassIndexer massIndexer(Collection<String> tenantIds) {
+		return massIndexer( tenantIds.isEmpty() ?
+				Collections.singletonList( DetachedBackendSessionContext.of( mappingContext, null ) ) :
+				tenantIds.stream()
+						.map( id -> DetachedBackendSessionContext.of( mappingContext, id ) )
+						.collect( Collectors.toList() )
+		);
+	}
+
+	public MassIndexer massIndexer(List<DetachedBackendSessionContext> detachedSessionContexts) {
+		StandalonePojoLoadingContext context = mappingContext.loadingContextBuilder().build();
+		PojoMassIndexer massIndexerDelegate = delegate.massIndexer( context, detachedSessionContexts );
 		return new StandalonePojoMassIndexer( massIndexerDelegate, context );
 	}
 
diff --git a/mapper/pojo-standalone/src/main/java/org/hibernate/search/mapper/pojo/standalone/scope/impl/StandalonePojoScopeMappingContext.java b/mapper/pojo-standalone/src/main/java/org/hibernate/search/mapper/pojo/standalone/scope/impl/StandalonePojoScopeMappingContext.java
index 1927cda04fa..9b24daa68f6 100644
--- a/mapper/pojo-standalone/src/main/java/org/hibernate/search/mapper/pojo/standalone/scope/impl/StandalonePojoScopeMappingContext.java
+++ b/mapper/pojo-standalone/src/main/java/org/hibernate/search/mapper/pojo/standalone/scope/impl/StandalonePojoScopeMappingContext.java
@@ -7,11 +7,10 @@
 package org.hibernate.search.mapper.pojo.standalone.scope.impl;
 
 import org.hibernate.search.engine.backend.mapping.spi.BackendMappingContext;
-import org.hibernate.search.engine.backend.session.spi.DetachedBackendSessionContext;
 import org.hibernate.search.mapper.pojo.standalone.loading.impl.StandalonePojoLoadingContext;
 
 public interface StandalonePojoScopeMappingContext extends BackendMappingContext {
 
-	StandalonePojoLoadingContext.Builder loadingContextBuilder(DetachedBackendSessionContext sessionContext);
+	StandalonePojoLoadingContext.Builder loadingContextBuilder();
 
 }
diff --git a/mapper/pojo-standalone/src/main/java/org/hibernate/search/mapper/pojo/standalone/session/impl/StandalonePojoSearchSession.java b/mapper/pojo-standalone/src/main/java/org/hibernate/search/mapper/pojo/standalone/session/impl/StandalonePojoSearchSession.java
index 5e803c7ebb9..05d71963120 100644
--- a/mapper/pojo-standalone/src/main/java/org/hibernate/search/mapper/pojo/standalone/session/impl/StandalonePojoSearchSession.java
+++ b/mapper/pojo-standalone/src/main/java/org/hibernate/search/mapper/pojo/standalone/session/impl/StandalonePojoSearchSession.java
@@ -7,6 +7,7 @@
 package org.hibernate.search.mapper.pojo.standalone.session.impl;
 
 import java.lang.invoke.MethodHandles;
+import java.util.Arrays;
 import java.util.Collection;
 import java.util.concurrent.CompletableFuture;
 import java.util.function.Consumer;
@@ -98,7 +99,7 @@ public boolean isOpen() {
 	@Override
 	public MassIndexer massIndexer(Collection<? extends Class<?>> types) {
 		checkOpenAndThrow();
-		return scope( types ).massIndexer( DetachedBackendSessionContext.of( this ) );
+		return scope( types ).massIndexer( Arrays.asList( DetachedBackendSessionContext.of( this ) ) );
 	}
 
 	@Override
@@ -189,7 +190,7 @@ public StandalonePojoSearchSessionMappingContext mappingContext() {
 	}
 
 	private StandalonePojoSelectionLoadingContextBuilder loadingContextBuilder() {
-		StandalonePojoLoadingContext.Builder builder = mappingContext.loadingContextBuilder( DetachedBackendSessionContext.of( this ) );
+		StandalonePojoLoadingContext.Builder builder = mappingContext.loadingContextBuilder();
 		if ( loadingOptionsContributor != null ) {
 			loadingOptionsContributor.accept( builder );
 		}