diff --git a/src/features/database/Database.module.css b/src/features/database/Database.module.css
index fa103b66..909df586 100644
--- a/src/features/database/Database.module.css
+++ b/src/features/database/Database.module.css
@@ -1259,3 +1259,18 @@
   flex: none;
   width: 2px;
 }
+
+/* Wrap large values instead of laying megabytes out as one line. */
+.largeCellEditor {
+  display: block;
+  box-sizing: border-box;
+  width: 100%;
+  height: min(60vh, 480px);
+  padding: 8px;
+  font: inherit;
+  color: inherit;
+  background: inherit;
+  white-space: pre-wrap;
+  overflow-wrap: anywhere;
+  resize: vertical;
+}
diff --git a/src/features/database/ExportDialog.test.tsx b/src/features/database/ExportDialog.test.tsx
new file mode 100644
index 00000000..3b06fa8c
--- /dev/null
+++ b/src/features/database/ExportDialog.test.tsx
@@ -0,0 +1,37 @@
+import { fireEvent, render, screen, waitFor } from "@testing-library/react";
+import { describe, expect, it, vi } from "vitest";
+import { commands } from "@/platform/ipc";
+import { ExportDialog } from "./ExportDialog";
+import { cellPreview } from "./cellPreview";
+
+vi.mock("./store", () => ({ closeDialog: vi.fn() }));
+vi.mock("@/workbench/contributions", () => ({ notifications: () => ({ notify: vi.fn() }) }));
+vi.mock("@tauri-apps/api/path", () => ({ homeDir: async () => "/home/test" }));
+
+describe("large value export", () => {
+  it("bounds preview values while exporting every row in full", async () => {
+    const full = JSON.stringify({ text: "\u4e2d text ".repeat(200_000), tail: "complete" });
+    const dbExportFile = vi.spyOn(commands, "dbExportFile").mockResolvedValue({ status: "ok", data: null });
+    const rows = [[full], ["short"], [null]];
+    render(
+      <ExportDialog
+        data={{ columns: [{ name: "payload", type: "jsonb" }], rows, table: "big", driver: "postgres" }}
+        source="public.big"
+        initialFormat="json"
+      />,
+    );
+    const preview = screen.getByLabelText("Export preview");
+    expect(JSON.parse(preview.textContent!)).toEqual([
+      { payload: cellPreview(full) },
+      { payload: "short" },
+      { payload: null },
+    ]);
+    await waitFor(() => expect(screen.getByLabelText("Output file")).toHaveValue("/home/test/big.json"));
+    fireEvent.click(screen.getByRole("button", { name: "Export to File" }));
+    await waitFor(() => expect(dbExportFile).toHaveBeenCalled());
+    const [path, contents] = dbExportFile.mock.calls[0]!;
+    expect(path).toBe("/home/test/big.json");
+    expect(JSON.parse(contents)).toEqual(rows.map(([payload]) => ({ payload })));
+    dbExportFile.mockRestore();
+  });
+});
diff --git a/src/features/database/ExportDialog.tsx b/src/features/database/ExportDialog.tsx
index 26994635..b8d9b014 100644
--- a/src/features/database/ExportDialog.tsx
+++ b/src/features/database/ExportDialog.tsx
@@ -17,6 +17,7 @@ import {
 import { CodePreview } from "./CodePreview";
 import { closeDialog } from "./store";
 import styles from "./Database.module.css";
+import { cellPreview } from "./cellPreview";
 
 const PREVIEW_ROWS = 100;
 /** Formats with a tabular layout (the options apply). */
@@ -59,7 +60,15 @@ export function ExportDialog({
   const tabular = TABULAR.has(format);
   const effective = tabular ? options : DEFAULT_EXPORT_OPTIONS;
   const preview = useMemo(
-    () => exportData(format, { ...data, rows: data.rows.slice(0, PREVIEW_ROWS) }, effective),
+    () =>
+      exportData(
+        format,
+        {
+          ...data,
+          rows: data.rows.slice(0, PREVIEW_ROWS).map((row) => row.map((v) => (v === null ? null : cellPreview(v)))),
+        },
+        effective,
+      ),
     [format, data, effective],
   );
   const text = () => exportData(format, data, effective);
diff --git a/src/features/database/Grid.test.tsx b/src/features/database/Grid.test.tsx
index 75b5e24f..200defe8 100644
--- a/src/features/database/Grid.test.tsx
+++ b/src/features/database/Grid.test.tsx
@@ -3,6 +3,8 @@ import { registerActions } from "@/platform/actions";
 import { fireEvent, render, screen } from "@testing-library/react";
 import { afterEach, describe, expect, it, vi } from "vitest";
 import { Grid } from "./Grid";
+import { CELL_PREVIEW_LIMIT, cellPreview } from "./cellPreview";
+import { exportData } from "./export";
 
 vi.mock("@tanstack/react-virtual", () => ({
   useVirtualizer: ({ count }: { count: number }) => ({
@@ -72,3 +74,59 @@ describe("database grid", () => {
     ]);
   });
 });
+
+describe("large database cells", () => {
+  const full = JSON.stringify({ text: "\u8bf4\u660e text \u6df7\u5408 ".repeat(200_000), tail: "complete" });
+  const columns = [{ name: "payload", type: "jsonb" }];
+
+  it("preserves short values and truncates only beyond the preview limit", () => {
+    for (const value of ["", "hello", "\u4e2d".repeat(CELL_PREVIEW_LIMIT)]) expect(cellPreview(value)).toBe(value);
+    expect(cellPreview(full)).toBe(full.slice(0, CELL_PREVIEW_LIMIT) + "\u2026");
+    expect(cellPreview("a".repeat(999) + "\ud83d\ude00tail")).toBe("a".repeat(999) + "\u2026");
+  });
+
+  it("bounds rendered text while copying and exporting the complete value", () => {
+    const writeText = vi.fn();
+    Object.defineProperty(navigator, "clipboard", { configurable: true, value: { writeText } });
+    render(<Grid columns={columns} rowCount={1} value={() => full} />);
+    const cell = screen.getByRole("gridcell");
+    expect(cell.textContent).toBe(cellPreview(full));
+    expect(cell.title).toBe(full.slice(0, 2000));
+    fireEvent.mouseDown(cell, { button: 0 });
+    fireEvent.keyDown(screen.getByRole("grid"), { key: "c", ctrlKey: true });
+    expect(writeText).toHaveBeenCalledWith(full);
+    expect(JSON.parse(exportData("json", { columns, rows: [[full]], table: "big", driver: "postgres" }))).toEqual([
+      { payload: full },
+    ]);
+  });
+
+  it("edits the full large value in a dialog and supports cancel and apply", () => {
+    const onEdit = vi.fn();
+    render(<Grid columns={columns} rowCount={1} value={() => full} editable onEdit={onEdit} />);
+    fireEvent.doubleClick(screen.getByRole("gridcell"));
+    expect(screen.getByRole("dialog")).toBeTruthy();
+    const editor = screen.getByRole("textbox") as HTMLTextAreaElement;
+    expect(editor.tagName).toBe("TEXTAREA");
+    expect(editor.value).toBe(full);
+    fireEvent.change(editor, { target: { value: full + "changed" } });
+    fireEvent.click(screen.getByRole("button", { name: "Cancel" }));
+    expect(onEdit).not.toHaveBeenCalled();
+    fireEvent.doubleClick(screen.getByRole("gridcell"));
+    fireEvent.change(screen.getByRole("textbox"), { target: { value: full + "changed" } });
+    fireEvent.click(screen.getByRole("button", { name: "Apply" }));
+    expect(onEdit).toHaveBeenCalledWith(0, 0, full + "changed");
+    expect(screen.queryByRole("dialog")).toBeNull();
+  });
+
+  it("keeps short values in the inline editor and preserves null display", () => {
+    const onEdit = vi.fn();
+    const { rerender } = render(<Grid columns={columns} rowCount={1} value={() => "short"} editable onEdit={onEdit} />);
+    fireEvent.doubleClick(screen.getByRole("gridcell"));
+    expect(screen.getByRole("textbox").tagName).toBe("INPUT");
+    fireEvent.change(screen.getByRole("textbox"), { target: { value: "updated" } });
+    fireEvent.keyDown(screen.getByRole("textbox"), { key: "Enter" });
+    expect(onEdit).toHaveBeenCalledWith(0, 0, "updated");
+    rerender(<Grid columns={columns} rowCount={1} value={() => null} />);
+    expect(screen.getByRole("gridcell").textContent).toBe("<null>");
+  });
+});
diff --git a/src/features/database/Grid.tsx b/src/features/database/Grid.tsx
index 3b05b4f6..f0d93202 100644
--- a/src/features/database/Grid.tsx
+++ b/src/features/database/Grid.tsx
@@ -6,10 +6,11 @@
 import { useEffect, useMemo, useRef, useState, type ClipboardEvent, type KeyboardEvent, type MouseEvent } from "react";
 import { useVirtualizer } from "@tanstack/react-virtual";
 import clsx from "clsx";
-import { Icon, showContextMenu, type MenuItem } from "@/ui";
+import { Dialog, Icon, showContextMenu, type MenuItem } from "@/ui";
 import { parseDelimited, toCsv, toTsv, type Cell } from "./model";
 import styles from "./Database.module.css";
 import { tx } from "@/platform/i18n";
+import { CELL_PREVIEW_LIMIT, cellPreview } from "./cellPreview";
 
 export interface GridColumn {
   name: string;
@@ -103,7 +104,7 @@ export function Grid(props: GridProps) {
     window.addEventListener("mouseup", stop);
     return () => window.removeEventListener("mouseup", stop);
   }, []);
-  const [editing, setEditing] = useState<{ row: number; col: number; text: string } | null>(null);
+  const [editing, setEditing] = useState<{ row: number; col: number; text: string; dialog: boolean } | null>(null);
   const columnKey = columns.map((c) => c.name).join("\u0000");
   const [widths, setWidths] = useState<number[]>([]);
   const [numeric, setNumeric] = useState<boolean[]>([]);
@@ -171,7 +172,8 @@ export function Grid(props: GridProps) {
 
   const startEdit = (row: number, col: number) => {
     if (!editable || props.rowState?.(row) === "deleted") return;
-    setEditing({ row, col, text: value(row, col) ?? "" });
+    const text = value(row, col) ?? "";
+    setEditing({ row, col, text, dialog: text.length > CELL_PREVIEW_LIMIT });
   };
 
   const onKeyDown = (e: KeyboardEvent<HTMLDivElement>) => {
@@ -302,6 +304,29 @@ export function Grid(props: GridProps) {
       onPaste={onPaste}
       onContextMenu={onContextMenu}
     >
+      {editing?.dialog && (
+        <Dialog
+          open
+          title={tx`Edit ${columns[editing.col]!.name}`}
+          width={720}
+          onClose={() => setEditing(null)}
+          buttons={[
+            { label: "Cancel", role: "cancel", onClick: () => setEditing(null) },
+            { label: "Apply", role: "default", onClick: commit },
+          ]}
+        >
+          <textarea
+            className={styles.largeCellEditor}
+            aria-label={`Edit ${columns[editing.col]!.name}`}
+            value={editing.text}
+            spellCheck={false}
+            wrap="soft"
+            onContextMenu={(e) => e.stopPropagation()}
+            onChange={(e) => setEditing({ ...editing, text: e.target.value })}
+            onKeyDown={(e) => e.stopPropagation()}
+          />
+        </Dialog>
+      )}
       <div className={styles.gridInner} style={{ width: totalWidth, height: virtualizer.getTotalSize() + ROW_H }}>
         <div className={clsx(styles.gridRow, styles.gridHeader)} style={{ gridTemplateColumns: template }} role="row">
           <div className={styles.rowNumber} />
@@ -368,7 +393,7 @@ export function Grid(props: GridProps) {
                 {state === "inserted" ? "+" : (props.rowNumber?.(r) ?? firstRowNumber + r)}
               </div>
               {columns.map((_, c) => {
-                if (editing && editing.row === r && editing.col === c) {
+                if (editing && !editing.dialog && editing.row === r && editing.col === c) {
                   return (
                     <input
                       key={c}
@@ -407,7 +432,11 @@ export function Grid(props: GridProps) {
                     onDoubleClick={() => startEdit(r, c)}
                     title={val != null && val.length > 40 ? val.slice(0, 2000) : undefined}
                   >
-                    {val === null ? <span className={styles.null}>&lt;null&gt;</span> : displayed(val, !!numeric[c])}
+                    {val === null ? (
+                      <span className={styles.null}>&lt;null&gt;</span>
+                    ) : (
+                      cellPreview(displayed(val, !!numeric[c]))
+                    )}
                   </div>
                 );
               })}
diff --git a/src/features/database/cellPreview.ts b/src/features/database/cellPreview.ts
new file mode 100644
index 00000000..c0a69b4d
--- /dev/null
+++ b/src/features/database/cellPreview.ts
@@ -0,0 +1,10 @@
+export const CELL_PREVIEW_LIMIT = 1000;
+
+/** Bound text layout without changing the underlying value or splitting a surrogate pair. */
+export function cellPreview(value: string): string {
+  if (value.length <= CELL_PREVIEW_LIMIT) return value;
+  let end = CELL_PREVIEW_LIMIT;
+  const last = value.charCodeAt(end - 1);
+  if (last >= 0xd800 && last <= 0xdbff) end--;
+  return value.slice(0, end) + "\u2026";
+}
diff --git a/src/platform/locales/text/zh.json b/src/platform/locales/text/zh.json
index 14586338..c0edc2d5 100644
--- a/src/platform/locales/text/zh.json
+++ b/src/platform/locales/text/zh.json
@@ -1,4 +1,5 @@
 {
+  "Edit {name}": "编辑 {name}",
   "The language server JDK ({path}) must be a full JDK with jdk.compiler, jdk.jdi and jdk.unsupported for Java language support and debugging. jdtls needs JDK {version} or newer. Download JDK {version}, choose a full JDK in {setting}, or set it to Auto.": "语言服务器 JDK（{path}）必须是包含 jdk.compiler、jdk.jdi 和 jdk.unsupported 的完整 JDK，才能支持 Java 语言功能和调试。jdtls 需要 JDK {version} 或更高版本。请下载 JDK {version}，在 {setting} 中选择完整 JDK，或设为自动。",
   "Apple's clangd does not run clang-tidy, so checks from .clang-tidy are not shown. Install clangd (LLVM) to get them.": "Apple 的 clangd 不运行 clang-tidy，因此不会显示 .clang-tidy 中配置的检查。请安装 clangd（LLVM）以启用这些检查。",
   "Newer dependency version available": "有更新的依赖版本可用",