feat: add last start time to ui table

app/schema.graphql

@@ -1336,6 +1336,7 @@ type ProjectSession implements Node {
   numTracesWithError: Int!
   firstInput: SpanIOValue
   lastOutput: SpanIOValue
+  lastStartTime: DateTime
   tokenUsage: TokenUsage!
   traces(first: Int = 50, last: Int, after: String, before: String): TraceConnection!
   traceLatencyMsQuantile(probability: Float!): Float

app/src/pages/project/SessionsTable.tsx

@@ -88,6 +88,7 @@ export function SessionsTable(props: SessionsTableProps) {
                 lastOutput {
                   value
                 }
+                lastStartTime
                 tokenUsage {
                   prompt
                   completion
@@ -138,6 +139,12 @@ export function SessionsTable(props: SessionsTableProps) {
       enableSorting: true,
       cell: TimestampCell,
     },
+    {
+      header: "last start time",
+      accessorKey: "lastStartTime",
+      enableSorting: false,
+      cell: TimestampCell,
+    },
     {
       header: "total tokens",
       accessorKey: "tokenCountTotal",

src/phoenix/server/api/context.py

@@ -32,6 +32,7 @@
     ProjectByNameDataLoader,
     RecordCountDataLoader,
     SessionIODataLoader,
+    SessionLastStartTimeDataLoader,
     SessionNumTracesDataLoader,
     SessionNumTracesWithErrorDataLoader,
     SessionTokenUsagesDataLoader,
@@ -76,6 +77,7 @@ class DataLoaders:
     record_counts: RecordCountDataLoader
     session_first_inputs: SessionIODataLoader
     session_last_outputs: SessionIODataLoader
+    session_last_start_times: SessionLastStartTimeDataLoader
     session_num_traces: SessionNumTracesDataLoader
     session_num_traces_with_error: SessionNumTracesWithErrorDataLoader
     session_token_usages: SessionTokenUsagesDataLoader

src/phoenix/server/api/dataloaders/__init__.py

@@ -20,6 +20,7 @@
 from .project_by_name import ProjectByNameDataLoader
 from .record_counts import RecordCountCache, RecordCountDataLoader
 from .session_io import SessionIODataLoader
+from .session_last_start_times import SessionLastStartTimeDataLoader
 from .session_num_traces import SessionNumTracesDataLoader
 from .session_num_traces_with_error import SessionNumTracesWithErrorDataLoader
 from .session_token_usages import SessionTokenUsagesDataLoader
@@ -52,6 +53,7 @@
     "MinStartOrMaxEndTimeDataLoader",
     "RecordCountDataLoader",
     "SessionIODataLoader",
+    "SessionLastStartTimeDataLoader",
     "SessionNumTracesDataLoader",
     "SessionNumTracesWithErrorDataLoader",
     "SessionTokenUsagesDataLoader",

src/phoenix/server/api/dataloaders/session_last_start_times.py

@@ -0,0 +1,42 @@
+from datetime import datetime
+from typing import Optional
+
+from openinference.semconv.trace import SpanAttributes
+from sqlalchemy import func, select
+from strawberry.dataloader import DataLoader
+from typing_extensions import TypeAlias
+
+from phoenix.db import models
+from phoenix.server.types import DbSessionFactory
+
+Key: TypeAlias = int
+Result: TypeAlias = Optional[datetime]
+
+
+class SessionLastStartTimeDataLoader(DataLoader[Key, Result]):
+    def __init__(self, db: DbSessionFactory) -> None:
+        super().__init__(load_fn=self._load_fn)
+        self._db = db
+
+    async def _load_fn(self, keys: list[Key]) -> list[Result]:
+        stmt = (
+            select(
+                models.Trace.project_session_rowid,
+                func.max(models.Trace.start_time).label("last_start_time"),
+            )
+            .where(models.Trace.project_session_rowid.in_(set(keys)))
+            .group_by(models.Trace.project_session_rowid)
+        )
+        async with self._db() as session:
+            result: dict[Key, Result] = {
+                id_: last_start_time
+                async for id_, last_start_time in await session.stream(stmt)
+                if id_ is not None
+            }
+        return [result.get(key) for key in keys]
+
+
+INPUT_VALUE = SpanAttributes.INPUT_VALUE.split(".")
+INPUT_MIME_TYPE = SpanAttributes.INPUT_MIME_TYPE.split(".")
+OUTPUT_VALUE = SpanAttributes.OUTPUT_VALUE.split(".")
+OUTPUT_MIME_TYPE = SpanAttributes.OUTPUT_MIME_TYPE.split(".")

src/phoenix/server/api/types/ProjectSession.py

@@ -78,6 +78,13 @@ async def last_output(
             value=record.value,
         )
 
+    @strawberry.field
+    async def last_start_time(
+        self,
+        info: Info[Context, None],
+    ) -> Optional[datetime]:
+        return await info.context.data_loaders.session_last_start_times.load(self.id_attr)
+
     @strawberry.field
     async def token_usage(
         self,

src/phoenix/server/app.py

@@ -88,6 +88,7 @@
     ProjectByNameDataLoader,
     RecordCountDataLoader,
     SessionIODataLoader,
+    SessionLastStartTimeDataLoader,
     SessionNumTracesDataLoader,
     SessionNumTracesWithErrorDataLoader,
     SessionTokenUsagesDataLoader,
@@ -617,6 +618,7 @@ def get_context() -> Context:
                 ),
                 session_first_inputs=SessionIODataLoader(db, "first_input"),
                 session_last_outputs=SessionIODataLoader(db, "last_output"),
+                session_last_start_times=SessionLastStartTimeDataLoader(db),
                 session_num_traces=SessionNumTracesDataLoader(db),
                 session_num_traces_with_error=SessionNumTracesWithErrorDataLoader(db),
                 session_token_usages=SessionTokenUsagesDataLoader(db),