diff --git a/flow/activities/flowable.go b/flow/activities/flowable.go
index 288282053c..fb2e3c4b48 100644
--- a/flow/activities/flowable.go
+++ b/flow/activities/flowable.go
@@ -515,13 +515,7 @@ func (a *FlowableActivity) SendWALHeartbeat(ctx context.Context) error {
 		return err
 	}
 
-	command := `
-		BEGIN;
-		DROP AGGREGATE IF EXISTS PEERDB_EPHEMERAL_HEARTBEAT(float4);
-		CREATE AGGREGATE PEERDB_EPHEMERAL_HEARTBEAT(float4) (SFUNC = float4pl, STYPE = float4);
-		DROP AGGREGATE PEERDB_EPHEMERAL_HEARTBEAT(float4);
-		END;
-		`
+	command := peerdbenv.PeerDBWALHeartbeatQuery()
 	// run above command for each Postgres peer
 	for _, pgPeer := range pgPeers {
 		activity.RecordHeartbeat(ctx, pgPeer.Name)
diff --git a/flow/activities/flowable_core.go b/flow/activities/flowable_core.go
index 3a052af371..5edca2aa92 100644
--- a/flow/activities/flowable_core.go
+++ b/flow/activities/flowable_core.go
@@ -11,7 +11,7 @@ import (
 
 	"github.com/jackc/pgx/v5"
 	"github.com/jackc/pgx/v5/pgxpool"
-	"github.com/yuin/gopher-lua"
+	lua "github.com/yuin/gopher-lua"
 	"go.temporal.io/sdk/activity"
 	"go.temporal.io/sdk/log"
 	"go.temporal.io/sdk/temporal"
@@ -97,25 +97,12 @@ func syncCore[TPull connectors.CDCPullConnectorCore, TSync connectors.CDCSyncCon
 		tblNameMapping[v.SourceTableIdentifier] = model.NewNameAndExclude(v.DestinationTableIdentifier, v.Exclude)
 	}
 
-	var srcConn TPull
-	if sessionID == "" {
-		srcConn, err = connectors.GetAs[TPull](ctx, config.Source)
-		if err != nil {
-			return nil, err
-		}
-		defer connectors.CloseConnector(ctx, srcConn)
-
-		if err := srcConn.SetupReplConn(ctx); err != nil {
-			return nil, err
-		}
-	} else {
-		srcConn, err = waitForCdcCache[TPull](ctx, a, sessionID)
-		if err != nil {
-			return nil, err
-		}
-		if err := srcConn.ConnectionActive(ctx); err != nil {
-			return nil, temporal.NewNonRetryableApplicationError("connection to source down", "disconnect", nil)
-		}
+	srcConn, err := waitForCdcCache[TPull](ctx, a, sessionID)
+	if err != nil {
+		return nil, err
+	}
+	if err := srcConn.ConnectionActive(ctx); err != nil {
+		return nil, temporal.NewNonRetryableApplicationError("connection to source down", "disconnect", nil)
 	}
 
 	batchSize := options.BatchSize
diff --git a/flow/connectors/utils/avro/avro_writer.go b/flow/connectors/utils/avro/avro_writer.go
index ad2597478a..1908d43972 100644
--- a/flow/connectors/utils/avro/avro_writer.go
+++ b/flow/connectors/utils/avro/avro_writer.go
@@ -197,7 +197,11 @@ func (p *peerDBOCFWriter) WriteRecordsToS3(
 		numRows, writeOcfError = p.WriteOCF(ctx, w)
 	}()
 
-	_, err = manager.NewUploader(s3svc).Upload(ctx, &s3.PutObjectInput{
+	uploader := manager.NewUploader(s3svc, func(u *manager.Uploader) {
+		u.PartSize = 4 * 1024 * 1024 * 1024
+	})
+
+	_, err = uploader.Upload(ctx, &s3.PutObjectInput{
 		Bucket: aws.String(bucketName),
 		Key:    aws.String(key),
 		Body:   r,
diff --git a/flow/peerdbenv/config.go b/flow/peerdbenv/config.go
index aadc38c36a..bcf1ac050e 100644
--- a/flow/peerdbenv/config.go
+++ b/flow/peerdbenv/config.go
@@ -66,11 +66,6 @@ func PeerDBCDCDiskSpillMemPercentThreshold() int {
 	return getEnvInt("PEERDB_CDC_DISK_SPILL_MEM_PERCENT_THRESHOLD", -1)
 }
 
-// PEERDB_DISABLE_ONE_SYNC
-func PeerDBDisableOneSync() bool {
-	return getEnvBool("PEERDB_DISABLE_ONE_SYNC", false)
-}
-
 // GOMEMLIMIT is a variable internal to Golang itself, we use this for internal targets, 0 means no maximum
 func PeerDBFlowWorkerMaxMemBytes() uint64 {
 	return getEnvUint[uint64]("GOMEMLIMIT", 0)
@@ -106,6 +101,15 @@ func PeerDBEnableWALHeartbeat() bool {
 	return getEnvBool("PEERDB_ENABLE_WAL_HEARTBEAT", false)
 }
 
+// PEERDB_WAL_HEARTBEAT_QUERY
+func PeerDBWALHeartbeatQuery() string {
+	return GetEnvString("PEERDB_WAL_HEARTBEAT_QUERY", `BEGIN;
+DROP AGGREGATE IF EXISTS PEERDB_EPHEMERAL_HEARTBEAT(float4);
+CREATE AGGREGATE PEERDB_EPHEMERAL_HEARTBEAT(float4) (SFUNC = float4pl, STYPE = float4);
+DROP AGGREGATE PEERDB_EPHEMERAL_HEARTBEAT(float4);
+END;`)
+}
+
 // PEERDB_ENABLE_PARALLEL_SYNC_NORMALIZE
 func PeerDBEnableParallelSyncNormalize() bool {
 	return getEnvBool("PEERDB_ENABLE_PARALLEL_SYNC_NORMALIZE", false)
diff --git a/flow/workflows/sync_flow.go b/flow/workflows/sync_flow.go
index e421759909..711928ef5c 100644
--- a/flow/workflows/sync_flow.go
+++ b/flow/workflows/sync_flow.go
@@ -30,38 +30,30 @@ func SyncFlowWorkflow(
 	parent := workflow.GetInfo(ctx).ParentWorkflowExecution
 	logger := log.With(workflow.GetLogger(ctx), slog.String(string(shared.FlowNameKey), config.FlowJobName))
 
-	enableOneSync := GetSideEffect(ctx, func(_ workflow.Context) bool {
-		return !peerdbenv.PeerDBDisableOneSync()
-	})
-	var fMaintain workflow.Future
-	var sessionID string
-	syncSessionCtx := ctx
-	if enableOneSync {
-		sessionOptions := &workflow.SessionOptions{
-			CreationTimeout:  5 * time.Minute,
-			ExecutionTimeout: 144 * time.Hour,
-			HeartbeatTimeout: time.Minute,
-		}
-		var err error
-		syncSessionCtx, err = workflow.CreateSession(ctx, sessionOptions)
-		if err != nil {
-			return err
-		}
-		defer workflow.CompleteSession(syncSessionCtx)
-		sessionID = workflow.GetSessionInfo(syncSessionCtx).SessionID
+	sessionOptions := &workflow.SessionOptions{
+		CreationTimeout:  5 * time.Minute,
+		ExecutionTimeout: 14 * 24 * time.Hour,
+		HeartbeatTimeout: time.Minute,
+	}
 
-		maintainCtx := workflow.WithActivityOptions(syncSessionCtx, workflow.ActivityOptions{
-			StartToCloseTimeout: 14 * 24 * time.Hour,
-			HeartbeatTimeout:    time.Minute,
-			WaitForCancellation: true,
-		})
-		fMaintain = workflow.ExecuteActivity(
-			maintainCtx,
-			flowable.MaintainPull,
-			config,
-			sessionID,
-		)
+	syncSessionCtx, err := workflow.CreateSession(ctx, sessionOptions)
+	if err != nil {
+		return err
 	}
+	defer workflow.CompleteSession(syncSessionCtx)
+
+	sessionID := workflow.GetSessionInfo(syncSessionCtx).SessionID
+	maintainCtx := workflow.WithActivityOptions(syncSessionCtx, workflow.ActivityOptions{
+		StartToCloseTimeout: 14 * 24 * time.Hour,
+		HeartbeatTimeout:    time.Minute,
+		WaitForCancellation: true,
+	})
+	fMaintain := workflow.ExecuteActivity(
+		maintainCtx,
+		flowable.MaintainPull,
+		config,
+		sessionID,
+	)
 
 	var stop, syncErr bool
 	currentSyncFlowNum := 0