diff --git a/vertx-oracle-client/src/main/java/io/vertx/oracleclient/impl/OracleJdbcConnection.java b/vertx-oracle-client/src/main/java/io/vertx/oracleclient/impl/OracleJdbcConnection.java
index f845da108..ff16d9a26 100644
--- a/vertx-oracle-client/src/main/java/io/vertx/oracleclient/impl/OracleJdbcConnection.java
+++ b/vertx-oracle-client/src/main/java/io/vertx/oracleclient/impl/OracleJdbcConnection.java
@@ -167,10 +167,8 @@ public Future<Void> beforeRecycle() {
   }
 
   @Override
-  public <R> Future<R> schedule(ContextInternal context, CommandBase<R> cmd) {
-    Promise<R> promise = context.promise();
-    this.context.emit(v -> doSchedule(cmd, promise));
-    return promise.future();
+  public <R> void schedule(CommandBase<R> cmd, Completable<R> handler) {
+    this.context.emit(v -> doSchedule(cmd, handler));
   }
 
   private <R> void doSchedule(CommandBase<R> cmd, Completable<R> handler) {
diff --git a/vertx-pg-client/src/main/java/io/vertx/pgclient/impl/PgSocketConnection.java b/vertx-pg-client/src/main/java/io/vertx/pgclient/impl/PgSocketConnection.java
index ce8b7d234..880bd6553 100644
--- a/vertx-pg-client/src/main/java/io/vertx/pgclient/impl/PgSocketConnection.java
+++ b/vertx-pg-client/src/main/java/io/vertx/pgclient/impl/PgSocketConnection.java
@@ -82,7 +82,9 @@ public void init() {
   // TODO RETURN FUTURE ???
   Future<Connection> sendStartupMessage(String username, String password, String database, Map<String, String> properties) {
     InitCommand cmd = new InitCommand(this, username, password, database, properties);
-    return schedule(context, cmd);
+    Promise<Connection> promise = context.promise();
+    schedule(cmd, promise);
+    return promise.future();
   }
 
   Future<Void> sendCancelRequestMessage(int processId, int secretKey) {
diff --git a/vertx-sql-client/src/main/java/io/vertx/sqlclient/impl/PreparedStatementImpl.java b/vertx-sql-client/src/main/java/io/vertx/sqlclient/impl/PreparedStatementImpl.java
index 582fd1c8a..e9e2223b0 100644
--- a/vertx-sql-client/src/main/java/io/vertx/sqlclient/impl/PreparedStatementImpl.java
+++ b/vertx-sql-client/src/main/java/io/vertx/sqlclient/impl/PreparedStatementImpl.java
@@ -101,7 +101,7 @@ void withPreparedStatement(PrepareOptions options, Tuple args, Handler<AsyncResu
       if (future == null) {
         // Lazy statement;
         PrepareStatementCommand prepare = new PrepareStatementCommand(sql, options, true, args.types());
-        conn.schedule(context, prepare).onComplete(promise);
+        conn.schedule(prepare, promise);
         future = promise.future();
       }
       future.onComplete(handler);
@@ -161,7 +161,7 @@ public Future<Void> close() {
       Promise<Void> promise = context.promise();
       if (this.promise == null) {
         CloseStatementCommand cmd = new CloseStatementCommand(future.result());
-        conn.schedule(context, cmd).onComplete(promise);
+        conn.schedule(cmd, promise);
       } else {
         if (future == null) {
           future = this.promise.future();
@@ -170,7 +170,7 @@ public Future<Void> close() {
         future.onComplete(ar -> {
           if (ar.succeeded()) {
             CloseStatementCommand cmd = new CloseStatementCommand(ar.result());
-            conn.schedule(context, cmd).onComplete(promise);
+            conn.schedule(cmd, promise);
           } else {
             promise.complete();
           }
@@ -191,7 +191,7 @@ void closeCursor(String cursorId, Promise<Void> promise) {
     future.onComplete(ar -> {
       if (ar.succeeded()) {
         CloseCursorCommand cmd = new CloseCursorCommand(cursorId, ar.result());
-        conn.schedule(context, cmd).onComplete(promise);
+        conn.schedule(cmd, promise);
       } else {
         promise.fail(ar.cause());
       }
diff --git a/vertx-sql-client/src/main/java/io/vertx/sqlclient/impl/QueryExecutor.java b/vertx-sql-client/src/main/java/io/vertx/sqlclient/impl/QueryExecutor.java
index fb9a094cb..cc9d6e456 100644
--- a/vertx-sql-client/src/main/java/io/vertx/sqlclient/impl/QueryExecutor.java
+++ b/vertx-sql-client/src/main/java/io/vertx/sqlclient/impl/QueryExecutor.java
@@ -58,7 +58,7 @@ public void executeSimpleQuery(CommandScheduler scheduler,
                           PromiseInternal<L> promise) {
     ContextInternal context = promise.context();
     QueryResultBuilder handler = createHandler(promise);
-    scheduler.schedule(context, new SimpleQueryCommand<>(sql, singleton, autoCommit, collector, handler)).onComplete(handler);
+    scheduler.schedule(new SimpleQueryCommand<>(sql, singleton, autoCommit, collector, handler), handler);
   }
 
   QueryResultBuilder<T, R, L> executeExtendedQuery(CommandScheduler scheduler,
@@ -88,7 +88,7 @@ QueryResultBuilder<T, R, L> executeExtendedQuery(CommandScheduler scheduler,
       autoCommit,
       collector,
       handler);
-    scheduler.schedule(context, cmd).onComplete(handler);
+    scheduler.schedule(cmd, handler);
     return handler;
   }
 
@@ -96,7 +96,7 @@ public void executeExtendedQuery(CommandScheduler scheduler, String sql, Prepare
     ContextInternal context = (ContextInternal) promise.context();
     QueryResultBuilder handler = this.createHandler(promise);
     ExtendedQueryCommand cmd = createExtendedQueryCommand(sql, options, autoCommit, arguments, handler);
-    scheduler.schedule(context, cmd).onComplete(handler);
+    scheduler.schedule(cmd, handler);
   }
 
   private ExtendedQueryCommand<T> createExtendedQueryCommand(String sql,
@@ -130,14 +130,14 @@ void executeBatchQuery(CommandScheduler scheduler,
       }
     }
     ExtendedQueryCommand<T> cmd = ExtendedQueryCommand.createBatch(preparedStatement.sql(), options, preparedStatement, batch, autoCommit, collector, handler);
-    scheduler.schedule(context, cmd).onComplete(handler);
+    scheduler.schedule(cmd, handler);
   }
 
   public void executeBatchQuery(CommandScheduler scheduler, String sql, PrepareOptions options, boolean autoCommit, List<Tuple> batch, PromiseInternal<L> promise) {
     ContextInternal context = promise.context();
     QueryResultBuilder handler = createHandler(promise);
     ExtendedQueryCommand<T> cmd = createBatchQueryCommand(sql, options, autoCommit, batch, handler);
-    scheduler.schedule(context, cmd).onComplete(handler);
+    scheduler.schedule(cmd, handler);
   }
 
   private ExtendedQueryCommand<T> createBatchQueryCommand(String sql,
diff --git a/vertx-sql-client/src/main/java/io/vertx/sqlclient/impl/QueryResultBuilder.java b/vertx-sql-client/src/main/java/io/vertx/sqlclient/impl/QueryResultBuilder.java
index 8998ccdb0..04ef6a3fb 100644
--- a/vertx-sql-client/src/main/java/io/vertx/sqlclient/impl/QueryResultBuilder.java
+++ b/vertx-sql-client/src/main/java/io/vertx/sqlclient/impl/QueryResultBuilder.java
@@ -17,6 +17,7 @@
 
 package io.vertx.sqlclient.impl;
 
+import io.vertx.core.Completable;
 import io.vertx.core.Future;
 import io.vertx.core.Promise;
 import io.vertx.core.internal.PromiseInternal;
@@ -30,7 +31,7 @@
 /**
  * A query result for building a {@link SqlResult}.
  */
-public class QueryResultBuilder<T, R extends SqlResultBase<T>, L extends SqlResult<T>> implements QueryResultHandler<T>, Promise<Boolean> {
+public class QueryResultBuilder<T, R extends SqlResultBase<T>, L extends SqlResult<T>> implements QueryResultHandler<T>, Completable<Boolean> {
 
   private final Promise<L> handler;
   private final Function<T, R> factory;
@@ -81,30 +82,19 @@ public <V> void addProperty(PropertyKind<V> property, V value) {
   }
 
   @Override
-  public boolean tryComplete(Boolean result) {
-    suspended = result;
-    if (failure != null) {
-      return tryFail(failure);
+  public void complete(Boolean aBoolean, Throwable throwable) {
+    if (throwable == null) {
+      suspended = aBoolean;
+      if (failure != null) {
+        handler.tryFail(failure);
+      } else {
+        handler.tryComplete((L) first);
+      }
     } else {
-      return handler.tryComplete((L) first);
+      handler.tryFail(throwable);
     }
   }
 
-  @Override
-  public boolean tryFail(Throwable cause) {
-    return handler.tryFail(cause);
-  }
-
-  @Override
-  public boolean tryFail(String message) {
-    return handler.tryFail(message);
-  }
-
-  @Override
-  public Future<Boolean> future() {
-    return handler.future().map(l -> isSuspended());
-  }
-
   public boolean isSuspended() {
     return suspended;
   }
diff --git a/vertx-sql-client/src/main/java/io/vertx/sqlclient/impl/SocketConnectionBase.java b/vertx-sql-client/src/main/java/io/vertx/sqlclient/impl/SocketConnectionBase.java
index 548a32512..af411b86b 100644
--- a/vertx-sql-client/src/main/java/io/vertx/sqlclient/impl/SocketConnectionBase.java
+++ b/vertx-sql-client/src/main/java/io/vertx/sqlclient/impl/SocketConnectionBase.java
@@ -194,10 +194,8 @@ public void close(Holder holder, Promise<Void> promise) {
   }
 
   @Override
-  public <R> Future<R> schedule(ContextInternal context, CommandBase<R> cmd) {
-    Promise<R> promise = context.promise();
-    this.context.emit(v -> doSchedule(cmd, promise));
-    return promise.future();
+  public <R> void schedule(CommandBase<R> cmd, Completable<R> handler) {
+    this.context.emit(v -> doSchedule(cmd, handler));
   }
 
   protected <R> void doSchedule(CommandBase<R> cmd, Completable<R> handler) {
diff --git a/vertx-sql-client/src/main/java/io/vertx/sqlclient/impl/TransactionImpl.java b/vertx-sql-client/src/main/java/io/vertx/sqlclient/impl/TransactionImpl.java
index 837dfb616..a52bdda20 100644
--- a/vertx-sql-client/src/main/java/io/vertx/sqlclient/impl/TransactionImpl.java
+++ b/vertx-sql-client/src/main/java/io/vertx/sqlclient/impl/TransactionImpl.java
@@ -57,10 +57,10 @@ public void fail() {
 
   private <R> void execute(CommandBase<R> cmd) {
     Completable<R> handler = cmd.handler;
-    connection.schedule(context, cmd).onComplete(handler);
+    connection.schedule(cmd, handler);
   }
 
-  private <T> Completable<T> wrap(CommandBase<?> cmd, Promise<T> handler) {
+  private <T> Completable<T> wrap(CommandBase<?> cmd, Completable<T> handler) {
     return (res, err) -> {
       synchronized (TransactionImpl.this) {
         pendingQueries--;
@@ -70,7 +70,7 @@ private <T> Completable<T> wrap(CommandBase<?> cmd, Promise<T> handler) {
     };
   }
 
-  public <R> void schedule(CommandBase<R> cmd, Promise<R> handler) {
+  public <R> void schedule(CommandBase<R> cmd, Completable<R> handler) {
     cmd.handler = wrap(cmd, handler);
     if (!schedule(cmd)) {
       handler.fail("Transaction already completed");
diff --git a/vertx-sql-client/src/main/java/io/vertx/sqlclient/impl/pool/SqlConnectionPool.java b/vertx-sql-client/src/main/java/io/vertx/sqlclient/impl/pool/SqlConnectionPool.java
index cc66f6daf..bd8665fc5 100644
--- a/vertx-sql-client/src/main/java/io/vertx/sqlclient/impl/pool/SqlConnectionPool.java
+++ b/vertx-sql-client/src/main/java/io/vertx/sqlclient/impl/pool/SqlConnectionPool.java
@@ -13,6 +13,7 @@
 
 import io.netty.channel.EventLoop;
 import io.vertx.core.*;
+import io.vertx.core.internal.PromiseInternal;
 import io.vertx.core.internal.net.NetSocketInternal;
 import io.vertx.core.net.SocketAddress;
 import io.vertx.core.spi.metrics.ClientMetrics;
@@ -181,28 +182,32 @@ private void dequeueMetric(Object metric) {
     }
   }
 
-  public <R> Future<R> execute(ContextInternal context, CommandBase<R> cmd) {
+  // TODO : try optimize without promise
+  public <R> void execute(CommandBase<R> cmd, Completable<R> handler) {
+    ContextInternal context = vertx.getOrCreateContext();
     Promise<Lease<PooledConnection>> p = context.promise();
     Object metric = enqueueMetric();
     pool.acquire(context, 0)
       .onComplete(p);
-    return p.future().compose(lease -> {
+    p.future().compose(lease -> {
       dequeueMetric(metric);
       PooledConnection pooled = lease.get();
       Connection conn = pooled.conn;
       Future<R> future;
       if (afterAcquire != null) {
         future = afterAcquire.apply(conn)
-          .compose(v -> pooled.schedule(context, cmd))
+          .compose(v -> Future.<R>future(d -> pooled.schedule(cmd, d)))
           .eventually(() -> beforeRecycle.apply(conn));
       } else {
-        future = pooled.schedule(context, cmd);
+        PromiseInternal<R> pp = context.promise();
+        pooled.schedule(cmd, pp);
+        future = pp;
       }
       return future.andThen(ar -> {
         pooled.refresh();
         lease.recycle();
       });
-    });
+    }).onComplete(handler);
   }
 
   public void acquire(ContextInternal context, long timeout, Completable<PooledConnection> handler) {
@@ -368,7 +373,8 @@ public DatabaseMetadata getDatabaseMetaData() {
     }
 
     @Override
-    public <R> Future<R> schedule(ContextInternal context, CommandBase<R> cmd) {
+    public <R> void schedule(CommandBase<R> cmd, Completable<R> handler) {
+      ContextInternal context = vertx.getOrCreateContext();
       QueryReporter queryReporter;
       VertxTracer tracer = vertx.tracer();
       ClientMetrics metrics = conn.metrics();
@@ -378,13 +384,17 @@ public <R> Future<R> schedule(ContextInternal context, CommandBase<R> cmd) {
       } else {
         queryReporter = null;
       }
-      Future<R> fut = conn.schedule(context, cmd);
       if (queryReporter != null) {
-        fut = fut.andThen(queryReporter::after);
+        Completable<R> ori = handler;
+        handler = (res, err) -> {
+          queryReporter.after(res, err);
+          ori.complete(res, err);
+        };
       }
-      return fut;
+      conn.schedule(cmd, handler);
     }
 
+
     /**
      * Close the underlying connection
      */
diff --git a/vertx-sql-client/src/main/java/io/vertx/sqlclient/impl/tracing/QueryReporter.java b/vertx-sql-client/src/main/java/io/vertx/sqlclient/impl/tracing/QueryReporter.java
index 82acd7e84..88ffe02c8 100644
--- a/vertx-sql-client/src/main/java/io/vertx/sqlclient/impl/tracing/QueryReporter.java
+++ b/vertx-sql-client/src/main/java/io/vertx/sqlclient/impl/tracing/QueryReporter.java
@@ -131,13 +131,13 @@ public void before() {
     }
   }
 
-  public void after(AsyncResult ar) {
+  public void after(Object res, Throwable err) {
     if (tracer != null) {
       QueryResultBuilder<?, ?, ?> qbr = (QueryResultBuilder) cmd.resultHandler();
-      receiveResponse(context, payload, ar.succeeded() ? qbr.first : null, ar.succeeded() ? null : ar.cause());
+      receiveResponse(context, payload, err == null ? qbr.first : null, err);
     }
     if (metrics != null) {
-      if (ar.succeeded()) {
+      if (err == null) {
         metrics.responseBegin(metric, null);
         metrics.responseEnd(metric);
       } else {
diff --git a/vertx-sql-client/src/main/java/io/vertx/sqlclient/internal/SqlClientBase.java b/vertx-sql-client/src/main/java/io/vertx/sqlclient/internal/SqlClientBase.java
index bf65e2109..b6af37871 100644
--- a/vertx-sql-client/src/main/java/io/vertx/sqlclient/internal/SqlClientBase.java
+++ b/vertx-sql-client/src/main/java/io/vertx/sqlclient/internal/SqlClientBase.java
@@ -17,6 +17,7 @@
 
 package io.vertx.sqlclient.internal;
 
+import io.vertx.core.Completable;
 import io.vertx.core.internal.ContextInternal;
 import io.vertx.core.internal.PromiseInternal;
 import io.vertx.sqlclient.PrepareOptions;
@@ -167,7 +168,7 @@ private void executeBatch(List<Tuple> batch, PromiseInternal<R> promise) {
   public void group(Handler<SqlClient> block) {
     GroupingClient grouping = new GroupingClient();
     block.handle(grouping);
-    schedule(context(), grouping.composite);
+    schedule(grouping.composite, (res, err) -> {});
   }
 
   private class GroupingClient extends SqlClientBase {
@@ -194,8 +195,8 @@ protected <T> PromiseInternal<T> promise() {
     }
 
     @Override
-    public <R> Future<R> schedule(ContextInternal context, CommandBase<R> cmd) {
-      return composite.add(context, cmd);
+    public <R> void schedule(CommandBase<R> cmd, Completable<R> handler) {
+      composite.add(cmd, handler);
     }
   }
 }
diff --git a/vertx-sql-client/src/main/java/io/vertx/sqlclient/internal/SqlConnectionBase.java b/vertx-sql-client/src/main/java/io/vertx/sqlclient/internal/SqlConnectionBase.java
index 2b37009ca..569b5231e 100644
--- a/vertx-sql-client/src/main/java/io/vertx/sqlclient/internal/SqlConnectionBase.java
+++ b/vertx-sql-client/src/main/java/io/vertx/sqlclient/internal/SqlConnectionBase.java
@@ -74,7 +74,9 @@ public C prepare(String sql, PrepareOptions options, Handler<AsyncResult<Prepare
   }
 
   public Future<PreparedStatement> prepare(String sql, PrepareOptions options) {
-    return schedule(context, new PrepareStatementCommand(sql, options, true))
+    Promise<io.vertx.sqlclient.internal.PreparedStatement> promise = context.promise();
+    schedule(new PrepareStatementCommand(sql, options, true), promise);
+    return promise.future()
       .compose(
       cr -> Future.succeededFuture(PreparedStatementImpl.create(conn, context, cr, autoCommit())),
       err -> {
@@ -113,12 +115,10 @@ public void handleClosed() {
   }
 
   @Override
-  public <R> Future<R> schedule(ContextInternal context, CommandBase<R> cmd) {
+  public <R> void schedule(CommandBase<R> cmd, Completable<R> handler) {
     if (tx != null) {
       // TODO
-      Promise<R> promise = context.promise();
-      tx.schedule(cmd, promise);
-      return promise.future();
+      tx.schedule(cmd, handler);
     } else {
       QueryReporter queryReporter;
       VertxTracer tracer = context.owner().tracer();
@@ -126,13 +126,13 @@ public <R> Future<R> schedule(ContextInternal context, CommandBase<R> cmd) {
       if (!(conn instanceof SqlConnectionPool.PooledConnection) && cmd instanceof QueryCommandBase && (tracer != null || metrics != null)) {
         queryReporter = new QueryReporter(tracer, metrics, context, (QueryCommandBase<?>) cmd, conn);
         queryReporter.before();
-        return conn
-          .schedule(context, cmd)
-          .andThen(ar -> {
-            queryReporter.after(ar);
+        conn
+          .schedule(cmd, (res, err) -> {
+            queryReporter.after(res, err);
+            handler.complete(res, err);
           });
       } else {
-        return conn.schedule(context, cmd);
+        conn.schedule(cmd, handler);
       }
     }
   }
diff --git a/vertx-sql-client/src/main/java/io/vertx/sqlclient/internal/command/CommandScheduler.java b/vertx-sql-client/src/main/java/io/vertx/sqlclient/internal/command/CommandScheduler.java
index 087cbdbcc..2d6e7a1f0 100644
--- a/vertx-sql-client/src/main/java/io/vertx/sqlclient/internal/command/CommandScheduler.java
+++ b/vertx-sql-client/src/main/java/io/vertx/sqlclient/internal/command/CommandScheduler.java
@@ -16,12 +16,20 @@
  */
 package io.vertx.sqlclient.internal.command;
 
+import io.vertx.core.Completable;
 import io.vertx.core.Future;
+import io.vertx.core.Promise;
 import io.vertx.core.internal.ContextInternal;
 
 @FunctionalInterface
 public interface CommandScheduler {
 
-  <R> Future<R> schedule(ContextInternal context, CommandBase<R> cmd);
+  default <R> Future<R> schedule(ContextInternal context, CommandBase<R> cmd) {
+    Promise<R> promise = context.promise();
+    schedule(cmd, promise);
+    return promise.future();
+  }
+
+  <R> void schedule(CommandBase<R> cmd, Completable<R> handler);
 
 }
diff --git a/vertx-sql-client/src/main/java/io/vertx/sqlclient/internal/command/CompositeCommand.java b/vertx-sql-client/src/main/java/io/vertx/sqlclient/internal/command/CompositeCommand.java
index 87b7a38e2..ed28068a3 100644
--- a/vertx-sql-client/src/main/java/io/vertx/sqlclient/internal/command/CompositeCommand.java
+++ b/vertx-sql-client/src/main/java/io/vertx/sqlclient/internal/command/CompositeCommand.java
@@ -1,5 +1,6 @@
 package io.vertx.sqlclient.internal.command;
 
+import io.vertx.core.Completable;
 import io.vertx.core.Future;
 import io.vertx.core.internal.ContextInternal;
 import io.vertx.core.internal.PromiseInternal;
@@ -11,11 +12,9 @@ public class CompositeCommand extends CommandBase<Void> {
 
   private final List<CommandBase<?>> commands = new ArrayList<>();
 
-  public <R> Future<R> add(ContextInternal context, CommandBase<R> cmd) {
-    PromiseInternal<R> promise = context.promise();
-    cmd.handler = promise;
+  public <R> void add(CommandBase<R> cmd, Completable<R> handler) {
+    cmd.handler = handler;
     commands.add(cmd);
-    return promise.future();
   }
 
   public List<CommandBase<?>> commands() {
diff --git a/vertx-sql-client/src/main/java/io/vertx/sqlclient/internal/pool/PoolImpl.java b/vertx-sql-client/src/main/java/io/vertx/sqlclient/internal/pool/PoolImpl.java
index bf269a080..a8fafba95 100644
--- a/vertx-sql-client/src/main/java/io/vertx/sqlclient/internal/pool/PoolImpl.java
+++ b/vertx-sql-client/src/main/java/io/vertx/sqlclient/internal/pool/PoolImpl.java
@@ -171,8 +171,8 @@ public Future<SqlConnection> getConnection() {
   }
 
   @Override
-  public <R> Future<R> schedule(ContextInternal context, CommandBase<R> cmd) {
-    return pool.execute(context, cmd);
+  public <R> void schedule(CommandBase<R> cmd, Completable<R> handler) {
+    pool.execute(cmd, handler);
   }
 
   private void acquire(ContextInternal context, long timeout, Completable<SqlConnectionPool.PooledConnection> completionHandler) {