diff --git a/service/src/main/java/bio/terra/tanagra/app/controller/objmapping/FromApiUtils.java b/service/src/main/java/bio/terra/tanagra/app/controller/objmapping/FromApiUtils.java
index 4b5ba60a2..c1c8569ae 100644
--- a/service/src/main/java/bio/terra/tanagra/app/controller/objmapping/FromApiUtils.java
+++ b/service/src/main/java/bio/terra/tanagra/app/controller/objmapping/FromApiUtils.java
@@ -503,7 +503,12 @@ private static ValueDisplayField buildRelationshipField(
 
   public static Literal fromApiObject(ApiLiteral apiLiteral) {
     return switch (apiLiteral.getDataType()) {
-      case INT64 -> Literal.forInt64(apiLiteral.getValueUnion().getInt64Val());
+        // JavaScript can't handle the full int64 range when parsing JSON, so parse them as strings.
+      case INT64 ->
+          Literal.forInt64(
+              apiLiteral.getValueUnion().getInt64Val() != null
+                  ? Long.parseLong(apiLiteral.getValueUnion().getInt64Val())
+                  : null);
       case STRING -> Literal.forString(apiLiteral.getValueUnion().getStringVal());
       case BOOLEAN -> Literal.forBoolean(apiLiteral.getValueUnion().isBoolVal());
       case DATE -> Literal.forDate(apiLiteral.getValueUnion().getDateVal());
diff --git a/service/src/main/java/bio/terra/tanagra/app/controller/objmapping/ToApiUtils.java b/service/src/main/java/bio/terra/tanagra/app/controller/objmapping/ToApiUtils.java
index 3f254f1c8..b2a20a4cb 100644
--- a/service/src/main/java/bio/terra/tanagra/app/controller/objmapping/ToApiUtils.java
+++ b/service/src/main/java/bio/terra/tanagra/app/controller/objmapping/ToApiUtils.java
@@ -90,7 +90,10 @@ public static ApiLiteral toApiObject(Literal literal) {
         new ApiLiteral().dataType(ApiDataType.fromValue(literal.getDataType().name()));
     return switch (literal.getDataType()) {
       case INT64 ->
-          apiLiteral.valueUnion(new ApiLiteralValueUnion().int64Val(literal.getInt64Val()));
+          // JavaScript can't handle the full int64 range when parsing JSON, so send them as
+          // strings.
+          apiLiteral.valueUnion(
+              new ApiLiteralValueUnion().int64Val(literal.getInt64Val().toString()));
       case STRING ->
           apiLiteral.valueUnion(new ApiLiteralValueUnion().stringVal(literal.getStringVal()));
       case BOOLEAN ->
diff --git a/service/src/main/resources/api/service_openapi.yaml b/service/src/main/resources/api/service_openapi.yaml
index 0a791ecbc..909e9711f 100644
--- a/service/src/main/resources/api/service_openapi.yaml
+++ b/service/src/main/resources/api/service_openapi.yaml
@@ -1522,8 +1522,8 @@ components:
             boolVal:
               type: boolean
             int64Val:
-              type: integer
-              format: int64
+              # Transfer int64s as strings to avoid overflowing JavaScript's number precision.
+              type: string
             stringVal:
               type: string
             dateVal:
diff --git a/ui/codegen.sh b/ui/codegen.sh
index 87c4bb256..f4b162c38 100755
--- a/ui/codegen.sh
+++ b/ui/codegen.sh
@@ -7,4 +7,4 @@ openapi-generator-cli generate -i ../service/src/main/resources/api/service_open
 # Generate plugin proto code.
 rm -rf src/proto
 mkdir src/proto
-npx protoc --proto_path=../underlay/src/main/proto/ --plugin=./node_modules/.bin/protoc-gen-ts_proto --ts_proto_out=./src/proto/ --ts_proto_opt=esModuleInterop=true --ts_proto_opt=outputClientImpl=false ../underlay/src/main/proto/criteriaselector/dataschema/*.proto ../underlay/src/main/proto/criteriaselector/configschema/*.proto ../underlay/src/main/proto/viz/*.proto
+npx protoc --proto_path=../underlay/src/main/proto/ --plugin=./node_modules/.bin/protoc-gen-ts_proto --ts_proto_out=./src/proto/ --ts_proto_opt=esModuleInterop=true --ts_proto_opt=outputClientImpl=false --ts_proto_opt=forceLong=bigint ../underlay/src/main/proto/criteriaselector/dataschema/*.proto ../underlay/src/main/proto/criteriaselector/configschema/*.proto ../underlay/src/main/proto/viz/*.proto
diff --git a/ui/src/addByCode.tsx b/ui/src/addByCode.tsx
index 1ba25c85c..54ff37858 100644
--- a/ui/src/addByCode.tsx
+++ b/ui/src/addByCode.tsx
@@ -204,7 +204,7 @@ export function AddByCode() {
                   return undefined;
                 }
 
-                const item = data[id]?.data as LookupEntryItem;
+                const item = data.get(id)?.data as LookupEntryItem;
                 if (!item) {
                   return undefined;
                 }
diff --git a/ui/src/addCohort.tsx b/ui/src/addCohort.tsx
index d6350fea8..40dc87749 100644
--- a/ui/src/addCohort.tsx
+++ b/ui/src/addCohort.tsx
@@ -117,7 +117,7 @@ export function AddCohort() {
                   return undefined;
                 }
 
-                const cohortData = data[id].data as CohortData;
+                const cohortData = data.get(id)?.data as CohortData;
                 if (!cohortData) {
                   return undefined;
                 }
diff --git a/ui/src/addCriteria.tsx b/ui/src/addCriteria.tsx
index a2fe0c468..0bb903992 100644
--- a/ui/src/addCriteria.tsx
+++ b/ui/src/addCriteria.tsx
@@ -21,7 +21,6 @@ import Loading from "components/loading";
 import { Search } from "components/search";
 import {
   TreeGrid,
-  TreeGridData,
   TreeGridId,
   TreeGridItem,
   TreeGridRowData,
@@ -353,9 +352,9 @@ function AddCriteria(props: AddCriteriaProps) {
 
   const search = useCallback(async () => {
     const children: DataKey[] = [];
-    const data: TreeGridData = {
-      root: { data: {}, children },
-    };
+    const data = new Map<TreeGridId, CriteriaItem>([
+      ["root", { data: {}, children }],
+    ]);
 
     if (query) {
       const res = await searchCriteria(
@@ -377,13 +376,13 @@ function AddCriteria(props: AddCriteriaProps) {
           },
           entry: entry,
         };
-        data[key] = item;
+        data.set(key, item);
       });
     }
 
     return data;
   }, [underlaySource, query, selectedOptions, optionsMap]);
-  const searchState = useSWRImmutable<TreeGridData>(
+  const searchState = useSWRImmutable<Map<TreeGridId, CriteriaItem>>(
     {
       component: "AddCriteria",
       underlayName: underlay.name,
@@ -523,7 +522,7 @@ function AddCriteria(props: AddCriteriaProps) {
         {!!query ? (
           <Paper>
             <Loading status={searchState}>
-              {!searchState.data?.root?.children?.length ? (
+              {!searchState.data?.get("root")?.children?.length ? (
                 <Empty
                   minHeight="300px"
                   image={emptyImage}
@@ -532,7 +531,7 @@ function AddCriteria(props: AddCriteriaProps) {
               ) : (
                 <TreeGrid
                   columns={columns}
-                  data={searchState.data ?? {}}
+                  data={searchState.data ?? new Map()}
                   rowCustomization={(
                     id: TreeGridId,
                     rowData: TreeGridRowData
@@ -541,11 +540,11 @@ function AddCriteria(props: AddCriteriaProps) {
                       return undefined;
                     }
 
-                    const item = searchState.data[id] as CriteriaItem;
-                    const option = optionsMap.get(item.entry.source);
-                    if (!option) {
+                    const item = searchState.data.get(id);
+                    const option = optionsMap.get(item?.entry?.source ?? "");
+                    if (!option || !item?.entry?.source) {
                       throw new Error(
-                        `Item source "${item.entry.source}" doesn't match any criteria config ID.`
+                        `Item source "${item?.entry?.source}" doesn't match any criteria config ID.`
                       );
                     }
 
@@ -556,7 +555,7 @@ function AddCriteria(props: AddCriteriaProps) {
                           <GridLayout colAlign="center">
                             <Button
                               data-testid={rowData[searchConfig.columns[0].key]}
-                              onClick={() => onClick(option, item.entry.data)}
+                              onClick={() => onClick(option, item.entry?.data)}
                               variant="outlined"
                             >
                               Add
@@ -577,5 +576,5 @@ function AddCriteria(props: AddCriteriaProps) {
 }
 
 type CriteriaItem = TreeGridItem & {
-  entry: MergedItem<DataEntry>;
+  entry?: MergedItem<DataEntry>;
 };
diff --git a/ui/src/cohortReview/cohortReview.tsx b/ui/src/cohortReview/cohortReview.tsx
index 1d60211ea..fc1408f46 100644
--- a/ui/src/cohortReview/cohortReview.tsx
+++ b/ui/src/cohortReview/cohortReview.tsx
@@ -315,7 +315,7 @@ function AnnotationComponent(props: {
 
   // TODO(tjennison): Expand handling of older and newer revisions and improve
   // their UI once the API is updated.
-  const values = props.instance?.annotations?.[props.annotation.id];
+  const values = props.instance?.annotations?.get(props.annotation.id);
   const currentValue = values?.find((v) => v.current)?.value;
   const latestValue = values?.[values?.length]?.value;
 
@@ -339,9 +339,12 @@ function AnnotationComponent(props: {
             props.instance.data.key
           ),
         (instance: ReviewInstance) => {
-          instance.annotations[props.annotation.id] = instance.annotations[
-            props.annotation.id
-          ]?.filter((v) => !v.current);
+          instance.annotations.set(
+            props.annotation.id,
+            (instance.annotations.get(props.annotation.id) ?? []).filter(
+              (v) => !v.current
+            )
+          );
         }
       );
     } else {
@@ -432,17 +435,17 @@ function createUpdateCurrentValue(
   value: DataValue
 ) {
   const annotations = instance.annotations;
-  const cur = annotations[annotationId]?.find((v) => v.current);
+  const cur = annotations.get(annotationId)?.find((v) => v.current);
   if (cur) {
     cur.value = value;
   } else {
-    annotations[annotationId] = [
-      ...(annotations[annotationId] ?? []),
+    annotations.set(annotationId, [
+      ...(annotations.get(annotationId) ?? []),
       {
         current: true,
         instanceId: instance.data.key,
         value: value,
       },
-    ];
+    ]);
   }
 }
diff --git a/ui/src/cohortReview/cohortReviewList.tsx b/ui/src/cohortReview/cohortReviewList.tsx
index 8e1a8dce7..a33615c68 100644
--- a/ui/src/cohortReview/cohortReviewList.tsx
+++ b/ui/src/cohortReview/cohortReviewList.tsx
@@ -33,7 +33,7 @@ import {
   TreeGridId,
   useArrayAsTreeGridData,
 } from "components/treegrid";
-import { Annotation, AnnotationType, CohortReview } from "data/source";
+import { AnnotationType, CohortReview } from "data/source";
 import { useStudySource } from "data/studySourceContext";
 import { useUnderlaySource } from "data/underlaySourceContext";
 import deepEqual from "deep-equal";
@@ -692,7 +692,7 @@ function Annotations() {
                   return undefined;
                 }
 
-                const annotation = data[id].data as Annotation;
+                const annotation = data.get(id)?.data;
                 if (!annotation) {
                   return undefined;
                 }
diff --git a/ui/src/cohortReview/participantsList.tsx b/ui/src/cohortReview/participantsList.tsx
index f09145fcc..edaf5b77b 100644
--- a/ui/src/cohortReview/participantsList.tsx
+++ b/ui/src/cohortReview/participantsList.tsx
@@ -125,9 +125,7 @@ function ParticipantsList(props: ParticipantsListProps) {
   );
 
   const data = useMemo(() => {
-    const data: TreeGridData = {
-      root: { data: {}, children: [] },
-    };
+    const data: TreeGridData = new Map([["root", { data: {}, children: [] }]]);
 
     instancesState.data
       ?.slice(
@@ -136,13 +134,16 @@ function ParticipantsList(props: ParticipantsListProps) {
       )
       .forEach((instance) => {
         const key = instance.data.key;
-        data[key] = { data: { ...instance.data } };
-        data.root?.children?.push(key);
+        data.set(key, { data: { ...instance.data } });
+        data.get("root")?.children?.push(key);
 
         annotationsState.data?.forEach((a) => {
-          const values = instance.annotations[a.id];
+          const values = instance.annotations.get(a.id);
           if (values) {
-            data[key].data[`t_${a.id}`] = values[values.length - 1].value;
+            const valueData = data.get(key)?.data;
+            if (valueData) {
+              valueData[`t_${a.id}`] = values[values.length - 1].value;
+            }
           }
         });
       });
diff --git a/ui/src/cohortReview/plugins/occurrenceTable.tsx b/ui/src/cohortReview/plugins/occurrenceTable.tsx
index 6595dd2a6..7ebcee65c 100644
--- a/ui/src/cohortReview/plugins/occurrenceTable.tsx
+++ b/ui/src/cohortReview/plugins/occurrenceTable.tsx
@@ -62,12 +62,10 @@ function OccurrenceTable({ id, config }: { id: string; config: Config }) {
 
   const data = useMemo(() => {
     const children: DataKey[] = [];
-    const data: TreeGridData = {
-      root: { data: {}, children },
-    };
+    const data: TreeGridData = new Map([["root", { data: {}, children }]]);
 
     context.rows[config.entity]?.forEach((o) => {
-      data[o.key] = { data: o };
+      data.set(o.key, { data: o });
       children.push(o.key);
     });
 
@@ -84,22 +82,25 @@ function OccurrenceTable({ id, config }: { id: string; config: Config }) {
 
   const sortedData = useMemo(() => {
     return produce(data, (data) => {
-      if (!data.root?.children) {
+      const root = data.get("root");
+      if (!root) {
         return;
       }
 
-      data.root.children = data.root.children.filter((child) =>
+      root.children = (root.children ?? []).filter((child) =>
         Object.entries(filterRegExps ?? {}).reduce(
           (cur: boolean, [col, re]) =>
             cur &&
-            re.test(stringifyDataValue(data[child].data[col] as DataValue)),
+            re.test(
+              stringifyDataValue(data.get(child)?.data?.[col] as DataValue)
+            ),
           true
         )
       );
-      data.root.children.sort((a, b) => {
+      root.children.sort((a, b) => {
         for (const o of searchState.sortOrders ?? []) {
-          const valA = data[a].data[o.column] as DataValue | undefined;
-          const valB = data[b].data[o.column] as DataValue | undefined;
+          const valA = data.get(a)?.data?.[o.column] as DataValue | undefined;
+          const valB = data.get(b)?.data?.[o.column] as DataValue | undefined;
           const c = compareDataValues(valA, valB);
           if (c !== 0) {
             return o.direction === TreeGridSortDirection.Asc ? c : -c;
diff --git a/ui/src/cohortReview/plugins/textSearch.tsx b/ui/src/cohortReview/plugins/textSearch.tsx
index ea79723d5..2a62538ff 100644
--- a/ui/src/cohortReview/plugins/textSearch.tsx
+++ b/ui/src/cohortReview/plugins/textSearch.tsx
@@ -185,7 +185,7 @@ function TextSearch({ id, config }: { id: string; config: Config }) {
       >
         <Stack spacing={1} alignItems="stretch">
           {entities.map((o) => (
-            <Paper key={o.key} sx={{ overflow: "hidden" }}>
+            <Paper key={String(o.key)} sx={{ overflow: "hidden" }}>
               <Stack
                 alignItems="flex-start"
                 sx={{
diff --git a/ui/src/components/treegrid.test.tsx b/ui/src/components/treegrid.test.tsx
index 3421a836c..5a5cbe2be 100644
--- a/ui/src/components/treegrid.test.tsx
+++ b/ui/src/components/treegrid.test.tsx
@@ -3,7 +3,12 @@ import CheckBoxIcon from "@mui/icons-material/CheckBox";
 import IconButton from "@mui/material/IconButton";
 import { render, screen } from "@testing-library/react";
 import userEvent from "@testing-library/user-event";
-import { TreeGrid, TreeGridData, TreeGridId } from "components/treegrid";
+import {
+  TreeGrid,
+  TreeGridData,
+  TreeGridId,
+  TreeGridItem,
+} from "components/treegrid";
 import React from "react";
 
 test("Table renders correctly", async () => {
@@ -27,33 +32,45 @@ test("Table renders correctly", async () => {
     },
   ];
 
-  const data: TreeGridData = {
-    root: {
-      data: {},
-      children: [1, 3],
-    },
-    1: {
-      data: {
-        col1: "1-col1",
-        col2: "1-col2",
+  const data = new Map<TreeGridId, TreeGridItem>([
+    [
+      "root",
+      {
+        data: {},
+        children: [1, 3],
       },
-      children: [2],
-    },
-    2: {
-      data: {
-        col1: "2-col1",
-        col2: "2-col2",
-        col3: "2-col3",
+    ],
+    [
+      1,
+      {
+        data: {
+          col1: "1-col1",
+          col2: "1-col2",
+        },
+        children: [2],
       },
-    },
-    3: {
-      data: {
-        col1: "3-col1",
-        col2: "3-col2",
-        col3: <AccountTreeIcon />,
+    ],
+    [
+      2,
+      {
+        data: {
+          col1: "2-col1",
+          col2: "2-col2",
+          col3: "2-col3",
+        },
       },
-    },
-  };
+    ],
+    [
+      3,
+      {
+        data: {
+          col1: "3-col1",
+          col2: "3-col2",
+          col3: <AccountTreeIcon />,
+        },
+      },
+    ],
+  ]);
 
   const rowCustomization = (id: TreeGridId) => {
     // Add variety to the rows.
diff --git a/ui/src/components/treegrid.tsx b/ui/src/components/treegrid.tsx
index f3e57afc2..0116f7eeb 100644
--- a/ui/src/components/treegrid.tsx
+++ b/ui/src/components/treegrid.tsx
@@ -31,12 +31,13 @@ import { useImmer } from "use-immer";
 import { standardDateString } from "util/date";
 import { spacing } from "util/spacing";
 
-export type TreeGridId = string | number;
+export type TreeGridId = string | number | bigint;
 export type TreeGridValue =
   | undefined
   | null
   | string
   | number
+  | bigint
   | boolean
   | object
   | JSX.Element
@@ -46,14 +47,15 @@ export type TreeGridRowData = {
   [key: string]: TreeGridValue;
 };
 
-export type TreeGridItem = {
+export type TreeGridItem<RowType extends TreeGridRowData = TreeGridRowData> = {
   children?: TreeGridId[];
-  data: TreeGridRowData;
+  data: RowType;
 };
 
-export type TreeGridData<ItemType extends TreeGridItem = TreeGridItem> = {
-  [key: TreeGridId]: ItemType;
-};
+export type TreeGridData<ItemType extends TreeGridItem = TreeGridItem> = Map<
+  TreeGridId,
+  ItemType
+>;
 
 export type TreeGridColumn = {
   key: string;
@@ -388,16 +390,18 @@ export function TreeGrid<ItemType extends TreeGridItem = TreeGridItem>(
 export function useArrayAsTreeGridData<
   T extends TreeGridRowData,
   K extends keyof T
->(array: T[], key: K) {
+>(array: T[], key: K): TreeGridData<TreeGridItem<T>> {
   return useMemo(() => {
     const children: TreeGridId[] = [];
-    const data: TreeGridData = {
-      root: { data: {}, children },
-    };
+    const data = new Map<TreeGridId, TreeGridItem<T>>([
+      // Force empty data here since it's never accessed but making it optional
+      // is a pain for "data" access everywhere.
+      ["root", { data: {} as T, children }],
+    ]);
 
     array?.forEach((a) => {
       const k = a[key] as TreeGridId;
-      data[k] = { data: a };
+      data.set(k, { data: a });
       children.push(k);
     });
 
@@ -432,13 +436,17 @@ function renderChildren(
 ): JSX.Element[] {
   const results: JSX.Element[] = [];
 
-  props.data[id]?.children?.forEach((childId) => {
-    const child = props.data[childId];
+  props.data.get(id)?.children?.forEach((childId) => {
+    const child = props.data.get(childId);
     if (!child) {
       return;
     }
 
     const childState = state.get(childId);
+
+    if (!child.data) {
+      throw new Error(`'data' is undefined for ${JSON.stringify(child)}`);
+    }
     const rowCustomization = props.rowCustomization?.(childId, child.data);
 
     const renderColumn = (
@@ -550,6 +558,9 @@ function renderChildren(
         }}
       >
         {props.columns.map((col, i) => {
+          if (!child.data) {
+            throw new Error(`'data' is undefined for ${JSON.stringify(child)}`);
+          }
           let value = child.data[col.key];
           const isNull = value === null;
           if (isNull) {
diff --git a/ui/src/criteria/attribute.tsx b/ui/src/criteria/attribute.tsx
index d210042bb..07229fddd 100644
--- a/ui/src/criteria/attribute.tsx
+++ b/ui/src/criteria/attribute.tsx
@@ -382,7 +382,7 @@ async function search(
   hintData.enumHintOptions.forEach((hint) => {
     const key = hint.value;
     if (
-      (typeof key === "string" || typeof key === "number") &&
+      (typeof key === "string" || typeof key === "bigint") &&
       hint.name.search(re) >= 0
     ) {
       results.push({
diff --git a/ui/src/criteria/classification.tsx b/ui/src/criteria/classification.tsx
index f9f449088..c66d2f6bc 100644
--- a/ui/src/criteria/classification.tsx
+++ b/ui/src/criteria/classification.tsx
@@ -198,13 +198,14 @@ class _ implements CriteriaPlugin<string> {
 function dataKey(key: DataKey, entityGroup: string): string {
   return JSON.stringify({
     entityGroup,
-    key,
+    stringVal: typeof key === "string" ? key : undefined,
+    bigIntVal: typeof key === "bigint" ? String(key) : undefined,
   });
 }
 
 function keyFromDataKey(key: string): DataKey {
   const parsed = JSON.parse(key);
-  return parsed.key;
+  return parsed.bigIntVal ? BigInt(parsed.bigIntVal) : parsed.stringVal;
 }
 
 type SearchState = {
@@ -215,7 +216,7 @@ type SearchState = {
   // The ancestor list of the item to view the hierarchy for.
   hierarchy?: string[];
   // The item to highlight and scroll to in the hierarchy.
-  highlightId?: DataKey;
+  highlightId?: TreeGridId;
 };
 
 type ClassificationEditProps = {
@@ -326,8 +327,8 @@ function ClassificationEdit(props: ClassificationEditProps) {
       hierarchy?: DataKey[],
       parent?: DataKey,
       prevData?: TreeGridData
-    ) => {
-      const data = prevData ?? {};
+    ): Map<TreeGridId, EntityNodeItem> => {
+      const data = prevData ?? new Map();
 
       const children: DataKey[] = [];
       nodes.forEach(({ source: entityGroup, data: node }) => {
@@ -349,7 +350,7 @@ function ClassificationEdit(props: ClassificationEditProps) {
         // Copy over existing children in case they're being loaded in
         // parallel. Grouping children and non-grouping, non-hierarchy nodes
         // always have no children.
-        let childChildren = data[key]?.children;
+        let childChildren = data.get(key)?.children;
         if (!childChildren) {
           if (
             (!hierarchy && group && parent) ||
@@ -367,17 +368,17 @@ function ClassificationEdit(props: ClassificationEditProps) {
           entityGroup,
           groupingNode: !!group && !parent,
         };
-        data[key] = cItem;
+        data.set(key, cItem);
       });
 
       if (parent) {
         // Store children even if the data isn't loaded yet.
-        data[parent] = { ...data[parent], children };
+        data.set(parent, { ...data.get(parent), children });
       } else {
-        data.root = {
-          children: [...(data?.root?.children || []), ...children],
+        data.set("root", {
+          children: [...(data?.get("root")?.children || []), ...children],
           data: {},
-        };
+        });
       }
 
       return data;
@@ -531,7 +532,7 @@ function ClassificationEdit(props: ClassificationEditProps) {
 
   // Partially update the state when expanding rows in the hierarchy view.
   const updateData = useCallback(
-    (data: TreeGridData) => {
+    (data: Map<TreeGridId, EntityNodeItem>) => {
       instancesState.mutate(data, { revalidate: false });
     },
     [instancesState]
@@ -635,7 +636,7 @@ function ClassificationEdit(props: ClassificationEditProps) {
             </GridBox>
           </GridBox>
           <Loading status={instancesState}>
-            {!instancesState.data?.root?.children?.length ? (
+            {!instancesState.data?.get("root")?.children?.length ? (
               <Empty
                 minHeight="300px"
                 image={emptyImage}
@@ -662,7 +663,7 @@ function ClassificationEdit(props: ClassificationEditProps) {
                   // TODO(tjennison): Make TreeGridData's type generic so we can
                   // avoid this type assertion. Also consider passing the
                   // TreeGridItem to the callback instead of the TreeGridRowData.
-                  const item = instancesState.data[id] as EntityNodeItem;
+                  const item = instancesState.data.get(id) as EntityNodeItem;
                   if (!item || item.groupingNode) {
                     return undefined;
                   }
@@ -793,7 +794,7 @@ function ClassificationEdit(props: ClassificationEditProps) {
                   }
 
                   const findEntityGroupConfig = () => {
-                    const item = data[id] as EntityNodeItem;
+                    const item = data.get(id) as EntityNodeItem;
                     if (item) {
                       const config = configEntityGroups(props.config).find(
                         (eg) => eg.id === item.entityGroup
@@ -871,7 +872,7 @@ function ClassificationEdit(props: ClassificationEditProps) {
                         <GridLayout rows sx={{ height: "fit-content" }}>
                           {localCriteria.selected.map((s, i) => (
                             <GridLayout
-                              key={s.key}
+                              key={String(s.key)}
                               cols
                               fillCol={0}
                               rowAlign="middle"
@@ -979,7 +980,7 @@ function HierarchySearchList(props: HierarchySearchListProps) {
             const title = String(n.data?.[nameAttribute(props.config)]);
             return (
               <Link
-                key={n.data.key}
+                key={String(n.data.key)}
                 component="button"
                 variant="body2"
                 color="inherit"
@@ -1034,7 +1035,7 @@ function ClassificationInline(props: ClassificationInlineProps) {
     <GridLayout rows height="auto">
       {decodedData.selected.map((s, i) => (
         <ValueDataEdit
-          key={s.key}
+          key={String(s.key)}
           hintEntity={entityGroup.occurrenceEntityIds[0]}
           relatedEntity={entityGroup.selectionEntity.name}
           hintKey={s.key}
@@ -1158,17 +1159,24 @@ function generateLookupFilters(
       throw new Error(`Unknown attribute "${ca}" in entity "${entity.name}".`);
     }
 
+    const values: tanagra.Literal[] = [];
+    codes.forEach((c) => {
+      try {
+        values.push(
+          literalFromDataValue(convertAttributeStringToDataValue(c, attribute))
+        );
+      } catch (e) {
+        // Don't attempt to match this attribute if conversion fails.
+      }
+    });
+
     operands.push({
       filterType: tanagra.FilterFilterTypeEnum.Attribute,
       filterUnion: {
         attributeFilter: {
           attribute: ca,
           operator: tanagra.AttributeFilterOperatorEnum.In,
-          values: codes.map((c) =>
-            literalFromDataValue(
-              convertAttributeStringToDataValue(c, attribute)
-            )
-          ),
+          values: values,
         },
       },
     });
diff --git a/ui/src/criteria/filterableGroup.tsx b/ui/src/criteria/filterableGroup.tsx
index a6d194f71..87ad04e3b 100644
--- a/ui/src/criteria/filterableGroup.tsx
+++ b/ui/src/criteria/filterableGroup.tsx
@@ -402,9 +402,8 @@ function FilterableGroupEdit(props: FilterableGroupEditProps) {
                     <GridLayout rows>
                       <Typography variant="body1">Query examples:</Typography>
                       {[...props.config.searchConfigs]
-                        .sort(
-                          (a, b) =>
-                            (a.displayOrder ?? 0) - (b.displayOrder ?? 0)
+                        .sort((a, b) =>
+                          Number((a.displayOrder ?? 0) - (b.displayOrder ?? 0))
                         )
                         .map((sc) => (
                           <Typography key={sc.name} variant="body2em">
diff --git a/ui/src/criteria/survey.tsx b/ui/src/criteria/survey.tsx
index ab832edaa..5370ecc21 100644
--- a/ui/src/criteria/survey.tsx
+++ b/ui/src/criteria/survey.tsx
@@ -278,7 +278,7 @@ function SurveyEdit(props: SurveyEditProps) {
 
   const processEntities = useCallback(
     (allEntityGroups: [string, EntityNode[]][]) => {
-      const data: EntityTreeGridData = {};
+      const data: EntityTreeGridData = new Map();
 
       allEntityGroups.forEach(([entityGroup, nodes]) => {
         nodes.forEach((node) => {
@@ -292,28 +292,29 @@ function SurveyEdit(props: SurveyEditProps) {
 
           const cItem: EntityNodeItem = {
             data: rowData,
-            children: data[key]?.children ?? [],
+            children: data.get(key)?.children ?? [],
             node: node,
             entityGroup,
             type:
-              data[key]?.type ??
+              data.get(key)?.type ??
               (node.childCount === 0
                 ? EntityNodeItemType.Answer
                 : EntityNodeItemType.Topic),
             parentKey: parentKey,
           };
-          data[key] = cItem;
+          data.set(key, cItem);
 
-          if (data[parentKey]) {
-            data[parentKey].children?.push(key);
+          const parent = data.get(parentKey);
+          if (parent) {
+            parent.children?.push(key);
             if (cItem.type === EntityNodeItemType.Answer) {
-              data[parentKey].type = EntityNodeItemType.Question;
+              parent.type = EntityNodeItemType.Question;
             }
           } else {
             const d = {
               key: parentKey,
             };
-            data[parentKey] = {
+            data.set(parentKey, {
               data: d,
               node: {
                 data: d,
@@ -325,7 +326,7 @@ function SurveyEdit(props: SurveyEditProps) {
                   ? EntityNodeItemType.Question
                   : EntityNodeItemType.Topic,
               children: [key],
-            };
+            });
           }
         });
       });
@@ -398,10 +399,10 @@ function SurveyEdit(props: SurveyEditProps) {
   const [filteredData, defaultExpanded] = useMemo(() => {
     const data = instancesState.data;
     if (!data) {
-      return [{}, []];
+      return [new Map(), []];
     }
     if (!searchState?.query) {
-      return [data, data["root"]?.children ?? []];
+      return [data, data.get("root")?.children ?? []];
     }
 
     // TODO(tjennison): Handle RegExp errors.
@@ -410,7 +411,11 @@ function SurveyEdit(props: SurveyEditProps) {
     const ancestors = new Set<TreeGridId>();
 
     const matchNode = (key: TreeGridId) => {
-      const node = data[key];
+      const node = data.get(key);
+      if (!node) {
+        throw new Error(`Tree node not found for ${key}.`);
+      }
+
       if (node.type != EntityNodeItemType.Topic) {
         for (const k in node.data) {
           if (re.test(String(node.data[k]))) {
@@ -429,8 +434,12 @@ function SurveyEdit(props: SurveyEditProps) {
 
     const filtered = produce(data, (data) => {
       for (const key in data) {
-        const node = data[key];
-        data[key].children =
+        const node = data.get(key);
+        if (!node) {
+          throw new Error(`Tree node not found for ${key}.`);
+        }
+
+        node.children =
           node.type === EntityNodeItemType.Question && matched.has(key)
             ? node.children
             : node.children?.filter((c) => ancestors.has(c) || matched.has(c));
@@ -475,7 +484,7 @@ function SurveyEdit(props: SurveyEditProps) {
             />
           </GridBox>
           <Loading status={instancesState}>
-            {!filteredData?.root?.children?.length ? (
+            {!filteredData?.get("root")?.children?.length ? (
               <Empty
                 minHeight="300px"
                 image={emptyImage}
@@ -499,7 +508,7 @@ function SurveyEdit(props: SurveyEditProps) {
                   // TODO(tjennison): Make TreeGridData's type generic so we can
                   // avoid this type assertion. Also consider passing the
                   // TreeGridItem to the callback instead of the TreeGridRowData.
-                  const item = instancesState.data[id];
+                  const item = instancesState.data.get(id);
                   if (!item) {
                     return undefined;
                   }
@@ -532,7 +541,7 @@ function SurveyEdit(props: SurveyEditProps) {
                                 const question =
                                   item.parentKey &&
                                   item.type === EntityNodeItemType.Answer
-                                    ? instancesState.data?.[item.parentKey]
+                                    ? instancesState.data?.get(item.parentKey)
                                     : undefined;
                                 const name =
                                   rowData[nameAttribute(props.config)];
@@ -582,7 +591,7 @@ function SurveyEdit(props: SurveyEditProps) {
                       <GridLayout rows sx={{ height: "fit-content" }}>
                         {groupedSelection.map((s, i) => (
                           <GridLayout
-                            key={s.key}
+                            key={String(s.key)}
                             rows
                             sx={{ height: "fit-content" }}
                           >
@@ -617,7 +626,7 @@ function SurveyEdit(props: SurveyEditProps) {
                             >
                               {s.children.map((child) => (
                                 <GridLayout
-                                  key={child.key}
+                                  key={String(child.key)}
                                   cols
                                   fillCol={0}
                                   rowAlign="middle"
@@ -707,7 +716,7 @@ function SurveyInline(props: SurveyInlineProps) {
     return (
       <GridBox sx={{ pb: 1, height: "auto" }}>
         <ValueDataEdit
-          key={sel.key}
+          key={String(sel.key)}
           hintEntity={entityGroup.occurrenceEntityIds[0]}
           relatedEntity={entityGroup.selectionEntity.name}
           hintKey={sel.key}
@@ -730,7 +739,7 @@ function SurveyInline(props: SurveyInlineProps) {
   return (
     <GridLayout rows height="auto">
       {groupedSelection.map((s, i) => (
-        <GridLayout key={s.key} rows height="auto">
+        <GridLayout key={String(s.key)} rows height="auto">
           <GridBox
             sx={{
               height: "auto",
diff --git a/ui/src/data/source.tsx b/ui/src/data/source.tsx
index 84a8f7bff..2d982fb3c 100644
--- a/ui/src/data/source.tsx
+++ b/ui/src/data/source.tsx
@@ -109,9 +109,7 @@ export type AnnotationValue = {
   current: boolean;
 };
 
-export type AnnotationEntry = {
-  [x: DataKey]: AnnotationValue[];
-};
+export type AnnotationEntry = Map<DataKey, AnnotationValue[]>;
 
 export type ReviewInstance = {
   data: DataEntry;
@@ -1620,7 +1618,7 @@ export function literalFromDataValue(value: DataValue): tanagra.Literal {
   return {
     dataType,
     valueUnion: {
-      int64Val: typeof value === "number" ? value : undefined,
+      int64Val: typeof value === "bigint" ? String(value) : undefined,
       stringVal: typeof value === "string" ? value : undefined,
       boolVal: typeof value === "boolean" ? value : undefined,
       dateVal: value instanceof Date ? value.toISOString() : undefined,
@@ -1634,7 +1632,9 @@ function dataValueFromLiteral(value?: tanagra.Literal | null): DataValue {
   }
   switch (value.dataType) {
     case tanagra.DataType.Int64:
-      return value.valueUnion?.int64Val ?? null;
+      return value.valueUnion?.int64Val
+        ? BigInt(value.valueUnion?.int64Val)
+        : null;
     case tanagra.DataType.String:
       return value.valueUnion?.stringVal ?? null;
     case tanagra.DataType.Date:
@@ -1656,7 +1656,7 @@ function dataValueFromLiteral(value?: tanagra.Literal | null): DataValue {
 
 export function protoFromDataKey(key: DataKey): keyProto.Key {
   return {
-    int64Key: typeof key === "number" ? key : undefined,
+    int64Key: typeof key === "bigint" ? key : undefined,
     stringKey: typeof key === "string" ? key : undefined,
   };
 }
@@ -1675,7 +1675,7 @@ export function dataKeyFromProto(key?: keyProto.Key): DataKey {
 
 export function protoFromDataValue(value: DataValue): valueProto.Value {
   return {
-    int64Value: typeof value === "number" ? value : undefined,
+    int64Value: typeof value === "bigint" ? value : undefined,
     stringValue: typeof value === "string" ? value : undefined,
     boolValue: typeof value === "boolean" ? value : undefined,
     timestampValue: value instanceof Date ? value : undefined,
@@ -1729,7 +1729,7 @@ function processEntitiesResponse(
         } else {
           ancestors = path
             .split(".")
-            .map((id) => (typeof data.key === "number" ? +id : id));
+            .map((id) => (typeof data.key === "bigint" ? String(id) : id));
         }
       }
 
@@ -1762,15 +1762,17 @@ function makeDataEntry(
   attributes?: { [key: string]: tanagra.ValueDisplay }
 ): DataEntry {
   const data: DataEntry = {
-    key: 0,
+    key: 0n,
   };
 
   processAttributes(data, attributes);
 
   const key = dataValueFromLiteral(attributes?.[primaryKey]?.value ?? null);
-  if (typeof key !== "string" && typeof key !== "number") {
+  if (typeof key !== "string" && typeof key !== "bigint") {
     throw new Error(
-      `Key attribute "${primaryKey}" not found in entity instance ${data}`
+      `Key attribute "${primaryKey}" not found in entity instance ${JSON.stringify(
+        data
+      )}`
     );
   }
   data.key = key;
@@ -2166,10 +2168,11 @@ function fromAPIReviewInstance(
 ): ReviewInstance {
   const data = makeDataEntry(primaryKey, instance.attributes);
 
-  const annotations: AnnotationEntry = {};
+  const annotations = new Map();
   for (const key in instance.annotations) {
-    annotations[key] = instance.annotations[key].map((v) =>
-      fromAPIAnnotationValue(v)
+    annotations.set(
+      key,
+      instance.annotations[key].map((v) => fromAPIAnnotationValue(v))
     );
   }
 
diff --git a/ui/src/data/types.ts b/ui/src/data/types.ts
index 389ab81a4..c0597591f 100644
--- a/ui/src/data/types.ts
+++ b/ui/src/data/types.ts
@@ -1,8 +1,8 @@
 import * as tanagraUnderlay from "tanagra-underlay/underlayConfig";
 import { standardDateString } from "util/date";
 
-export type DataKey = string | number;
-export type DataValue = null | string | number | boolean | Date;
+export type DataKey = string | number | bigint;
+export type DataValue = null | string | number | bigint | boolean | Date;
 
 export type DataEntry = {
   key: DataKey;
@@ -53,6 +53,7 @@ export function convertAttributeStringToDataValue(
 ): DataValue {
   switch (attribute.dataType) {
     case tanagraUnderlay.SZDataType.INT64:
+      return BigInt(value);
     case tanagraUnderlay.SZDataType.DOUBLE:
       return Number(value);
     case tanagraUnderlay.SZDataType.BOOLEAN:
diff --git a/ui/src/export.tsx b/ui/src/export.tsx
index 4a65cc5ef..213c204d3 100644
--- a/ui/src/export.tsx
+++ b/ui/src/export.tsx
@@ -496,13 +496,13 @@ function PreviewTable(props: PreviewTableProps) {
             props.featureSets
           );
 
-          const data: TreeGridData = {
-            root: { data: {}, children: [] },
-          };
+          const data: TreeGridData = new Map([
+            ["root", { data: {}, children: [] }],
+          ]);
 
           res.data.forEach((entry, i) => {
-            data[i] = { data: entry };
-            data.root?.children?.push(i);
+            data.set(i, { data: entry });
+            data.get("root")?.children?.push(i);
           });
 
           return {
@@ -572,7 +572,8 @@ function PreviewTable(props: PreviewTableProps) {
                   </Typography>
                 </GridBox>
               ) : tabDataState.data?.[tab]?.data ? (
-                tabDataState.data?.[tab]?.data?.root?.children?.length ? (
+                tabDataState.data?.[tab]?.data?.get("root")?.children
+                  ?.length ? (
                   <TreeGrid
                     data={tabDataState.data?.[tab]?.data}
                     columns={props.occurrenceFilters[tab]?.attributes.map(
diff --git a/ui/src/fakeApis.ts b/ui/src/fakeApis.ts
index dcd6ec7d0..0f9b52fc6 100644
--- a/ui/src/fakeApis.ts
+++ b/ui/src/fakeApis.ts
@@ -129,7 +129,7 @@ export class FakeUnderlaysApi {
               value: {
                 dataType: tanagra.DataType.Int64,
                 valueUnion: {
-                  int64Val: 1234,
+                  int64Val: "1234",
                 },
               },
             },
@@ -163,7 +163,7 @@ export class FakeUnderlaysApi {
                     value: {
                       dataType: tanagra.DataType.Int64,
                       valueUnion: {
-                        int64Val: 8515,
+                        int64Val: "8515",
                       },
                     },
                   },
@@ -175,7 +175,7 @@ export class FakeUnderlaysApi {
                     value: {
                       dataType: tanagra.DataType.Int64,
                       valueUnion: {
-                        int64Val: 8516,
+                        int64Val: "8516",
                       },
                     },
                   },
diff --git a/ui/src/featureSet/addFeatureSet.tsx b/ui/src/featureSet/addFeatureSet.tsx
index f02cd988d..518831629 100644
--- a/ui/src/featureSet/addFeatureSet.tsx
+++ b/ui/src/featureSet/addFeatureSet.tsx
@@ -122,7 +122,7 @@ export function AddFeatureSet() {
                   return undefined;
                 }
 
-                const featureSetData = data[id].data as FeatureSetData;
+                const featureSetData = data.get(id)?.data as FeatureSetData;
                 if (!featureSetData) {
                   return undefined;
                 }
diff --git a/ui/src/featureSet/featureSet.tsx b/ui/src/featureSet/featureSet.tsx
index 8486e6719..dd282dee0 100644
--- a/ui/src/featureSet/featureSet.tsx
+++ b/ui/src/featureSet/featureSet.tsx
@@ -340,13 +340,13 @@ function Preview() {
             true
           );
 
-          const data: TreeGridData = {
-            root: { data: {}, children: [] },
-          };
+          const data: TreeGridData = new Map([
+            ["root", { data: {}, children: [] }],
+          ]);
 
           res.data.forEach((entry, i) => {
-            data[i] = { data: entry };
-            data.root?.children?.push(i);
+            data.set(i, { data: entry });
+            data.get("root")?.children?.push(i);
           });
 
           return {
@@ -371,7 +371,7 @@ function Preview() {
                 id: data.name,
                 title: data.name,
                 render: () =>
-                  data.data.root?.children?.length ? (
+                  data.data.get("root")?.children?.length ? (
                     previewOccurrences[i] ? (
                       <PreviewTable
                         occurrence={previewOccurrences[i]}
diff --git a/ui/src/sampleApp/studiesList.tsx b/ui/src/sampleApp/studiesList.tsx
index b3feecd81..1f30e369a 100644
--- a/ui/src/sampleApp/studiesList.tsx
+++ b/ui/src/sampleApp/studiesList.tsx
@@ -78,9 +78,7 @@ export function StudiesList() {
 
   const data = useMemo(() => {
     const children: DataKey[] = [];
-    const data: TreeGridData = {
-      root: { data: {}, children },
-    };
+    const data: TreeGridData = new Map([["root", { data: {}, children }]]);
 
     studiesState.data?.forEach((study) => {
       const key = study.id;
@@ -122,7 +120,7 @@ export function StudiesList() {
           ),
         },
       };
-      data[key] = item;
+      data.set(key, item);
     });
 
     return data;
@@ -136,7 +134,7 @@ export function StudiesList() {
       <Header />
       <Loading status={studiesState}>
         <GridLayout rows spacing={4}>
-          {!!data?.root?.children?.length ? (
+          {!!data?.get("root")?.children?.length ? (
             <TreeGrid columns={columns} data={data} />
           ) : (
             <Empty
diff --git a/ui/src/sampleApp/studyOverview.tsx b/ui/src/sampleApp/studyOverview.tsx
index edf5e3245..62273fa5f 100644
--- a/ui/src/sampleApp/studyOverview.tsx
+++ b/ui/src/sampleApp/studyOverview.tsx
@@ -110,9 +110,7 @@ export function StudyOverview() {
 
   const data = useMemo(() => {
     const children: DataKey[] = [];
-    const data: TreeGridData = {
-      root: { data: {}, children },
-    };
+    const data: TreeGridData = new Map([["root", { data: {}, children }]]);
 
     artifactsState.data?.forEach((artifact) => {
       const key = `${artifact.type}~${artifact.id}`;
@@ -144,7 +142,7 @@ export function StudyOverview() {
           ),
         },
       };
-      data[key] = item;
+      data.set(key, item);
     });
 
     return data;
@@ -202,7 +200,7 @@ export function StudyOverview() {
           </GridLayout>
         </GridBox>
         <Loading status={artifactsState}>
-          {!!data?.root?.children?.length ? (
+          {!!data?.get("root")?.children?.length ? (
             <TreeGrid
               columns={columns}
               data={data}
diff --git a/ui/src/viz/viz.ts b/ui/src/viz/viz.ts
index 5fb0932e9..0e8f86dc2 100644
--- a/ui/src/viz/viz.ts
+++ b/ui/src/viz/viz.ts
@@ -62,11 +62,20 @@ export function processFilterCountValues(
         if (!isValid(value)) {
           value = "Unknown";
         }
+        if (typeof value === "bigint") {
+          value = Number(value);
+        }
 
         let name: string | undefined = undefined;
         let numericId: number | undefined = undefined;
         let stringId: string | undefined = undefined;
         if (a.numericBucketing) {
+          if (typeof value !== "number") {
+            throw new Error(
+              `Numeric bucketing cannot be applied to non-numeric ${value}.`
+            );
+          }
+
           const thresholds = a.numericBucketing.thresholds ?? [];
           if (!thresholds.length) {
             const intervals = a.numericBucketing.intervals;
@@ -76,7 +85,7 @@ export function processFilterCountValues(
               );
             }
 
-            for (let i = 0; i < intervals.count + 1; i++) {
+            for (let i = 0; i < intervals.count + 1n; i++) {
               thresholds.push(
                 intervals.min + i * (intervals.max - intervals.min)
               );
@@ -192,7 +201,7 @@ export function processFilterCountValues(
 
   const limit = vizSource.attributes[0].limit;
   if (limit) {
-    let count = 0;
+    let count = 0n;
     for (let i = 1; i < arr.length; i++) {
       const ka = arr[i].keys[0];
       const kb = arr[i - 1].keys[0];