From e4c56e6165b7943634062d3ac778cd1cf24f2db0 Mon Sep 17 00:00:00 2001
From: zipg <geeky@foxmail.com>
Date: Thu, 16 Jul 2026 16:32:52 +0800
Subject: [PATCH] feat(sqlserver): add execution plan support

---
 .../components/explain/ExplainPlanViewer.vue  |   3 +-
 .../query/sqlserverExplainPlan.spec.ts        |  92 +++++++++++
 apps/desktop/src/lib/backend/http.ts          |   2 +
 apps/desktop/src/lib/backend/tauri.ts         |   2 +
 apps/desktop/src/lib/diagram/explainPlan.ts   | 142 ++++++++++++++++-
 .../queryStore.sqlserverExplain.spec.ts       | 146 ++++++++++++++++++
 apps/desktop/src/stores/queryStore.ts         |  82 +++++++++-
 apps/desktop/src/types/database.ts            |   2 +-
 .../assets/database-drivers.manifest.json     |   2 +-
 crates/dbx-core/src/db/sqlserver.rs           |  47 +++++-
 crates/dbx-core/src/query.rs                  |  56 +++++--
 crates/dbx-core/src/query_execution_sql.rs    |  66 ++++++++
 crates/dbx-web/src/routes/query.rs            |   3 +
 package.json                                  |   1 +
 pnpm-lock.yaml                                |   9 ++
 src-tauri/src/commands/query.rs               |   4 +
 16 files changed, 636 insertions(+), 23 deletions(-)
 create mode 100644 apps/desktop/src/lib/__tests__/query/sqlserverExplainPlan.spec.ts
 create mode 100644 apps/desktop/src/stores/__tests__/queryStore.sqlserverExplain.spec.ts

diff --git a/apps/desktop/src/components/explain/ExplainPlanViewer.vue b/apps/desktop/src/components/explain/ExplainPlanViewer.vue
index 8a0caf38e..fbde5be39 100644
--- a/apps/desktop/src/components/explain/ExplainPlanViewer.vue
+++ b/apps/desktop/src/components/explain/ExplainPlanViewer.vue
@@ -45,6 +45,7 @@ const rawContent = computed(() => {
 });
 
 const isRawString = computed(() => typeof props.plan?.raw === "string");
+const rawFormatLabel = computed(() => (props.plan?.databaseType === "sqlserver" ? "XML" : isRawString.value ? "TEXT" : "JSON"));
 const nodeCount = computed(() => (props.plan ? flattenExplainPlanNodes(props.plan.nodes).length : 0));
 
 function tableCellText(value: unknown): string {
@@ -77,7 +78,7 @@ function tableCellText(value: unknown): string {
         <Button v-if="plan" size="sm" :variant="activeView === 'raw' ? 'secondary' : 'ghost'" class="h-6 px-2 text-xs gap-1" @click="activeView = 'raw'">
           <FileText v-if="isRawString" class="h-3.5 w-3.5" />
           <Braces v-else class="h-3.5 w-3.5" />
-          {{ isRawString ? "TEXT" : "JSON" }}
+          {{ rawFormatLabel }}
         </Button>
         <Button v-if="hasTableView" size="sm" :variant="activeView === 'table' ? 'secondary' : 'ghost'" class="h-6 px-2 text-xs gap-1" @click="activeView = 'table'">
           <Table2 class="h-3.5 w-3.5" />
diff --git a/apps/desktop/src/lib/__tests__/query/sqlserverExplainPlan.spec.ts b/apps/desktop/src/lib/__tests__/query/sqlserverExplainPlan.spec.ts
new file mode 100644
index 000000000..59bdfe267
--- /dev/null
+++ b/apps/desktop/src/lib/__tests__/query/sqlserverExplainPlan.spec.ts
@@ -0,0 +1,92 @@
+import { DOMParser } from "@xmldom/xmldom";
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+import { flattenExplainPlanNodes, parseExplainResult, sqlServerExplainResult, supportsExplainPlan } from "@/lib/diagram/explainPlan";
+import type { QueryResult } from "@/types/database";
+
+const SHOWPLAN_XML = `<ShowPlanXML xmlns="http://schemas.microsoft.com/sqlserver/2004/07/showplan">
+  <BatchSequence><Batch><Statements><StmtSimple><QueryPlan>
+    <RelOp NodeId="0" PhysicalOp="Sort" LogicalOp="Sort" EstimateRows="2" EstimatedTotalSubtreeCost="0.029466" AvgRowSize="36">
+      <Sort>
+        <RelOp NodeId="1" PhysicalOp="Index Seek" LogicalOp="Index Seek" EstimateRows="1" EstimatedRowsRead="4" EstimateIO="0.003125" EstimateCPU="0.0001581" EstimatedTotalSubtreeCost="0.0034412" AvgRowSize="16">
+          <IndexScan>
+            <Object Database="[dbx_explain_plan_test]" Schema="[dbo]" Table="[orders]" Index="[ix_orders_customer_status]" />
+            <SeekPredicates><SeekPredicateNew><SeekKeys><Prefix>
+              <RangeExpressions><ScalarOperator ScalarString="[orders].[status]='paid'" /></RangeExpressions>
+            </Prefix></SeekKeys></SeekPredicateNew></SeekPredicates>
+          </IndexScan>
+        </RelOp>
+      </Sort>
+    </RelOp>
+  </QueryPlan></StmtSimple></Statements></Batch></BatchSequence>
+</ShowPlanXML>`;
+
+function result(columns: string[], rows: unknown[][]): QueryResult {
+  return { columns, rows, affected_rows: 0, execution_time_ms: 1 };
+}
+
+describe("SQL Server explain plan", () => {
+  beforeEach(() => {
+    vi.stubGlobal("DOMParser", DOMParser);
+  });
+
+  afterEach(() => {
+    vi.unstubAllGlobals();
+  });
+
+  it("is enabled by the driver capability manifest", () => {
+    expect(supportsExplainPlan("sqlserver")).toBe(true);
+  });
+
+  it("parses SHOWPLAN XML into its operator hierarchy", () => {
+    const planResult = result(["Microsoft SQL Server 2005 XML Showplan"], [[SHOWPLAN_XML]]);
+    expect(sqlServerExplainResult([result([], []), planResult, result([], [])])).toEqual({ result: planResult });
+    const plan = parseExplainResult("sqlserver", planResult);
+    const nodes = flattenExplainPlanNodes(plan.nodes);
+
+    expect(plan.databaseType).toBe("sqlserver");
+    expect(plan.raw).toBe(SHOWPLAN_XML);
+    expect(nodes).toHaveLength(2);
+    expect(nodes[0]).toMatchObject({ id: "0", nodeType: "Sort", rows: "2", cost: "0.029466" });
+    expect(nodes[1]).toMatchObject({
+      id: "1",
+      nodeType: "Index Seek",
+      relation: "dbo.orders",
+      index: "ix_orders_customer_status",
+      rows: "1",
+      cost: "0.0034412",
+    });
+    expect(nodes[1].details).toContain("Estimated Rows Read: 4");
+    expect(nodes[1].details).toContain("Expression: [orders].[status]='paid'");
+  });
+
+  it("surfaces a SQL Server batch error instead of treating it as a plan", () => {
+    expect(sqlServerExplainResult([result(["Error"], [["Invalid object name 'missing_table'"]])])).toEqual({
+      error: "Invalid object name 'missing_table'",
+    });
+  });
+
+  it("rejects malformed SHOWPLAN XML", () => {
+    const malformed = result(["Microsoft SQL Server 2005 XML Showplan"], [["<ShowPlanXML><RelOp></ShowPlanXML>"]]);
+
+    expect(() => parseExplainResult("sqlserver", malformed)).toThrow("Invalid SQL Server ShowPlan XML");
+  });
+
+  it("rejects truncated SHOWPLAN XML", () => {
+    const truncated = result(["Microsoft SQL Server 2005 XML Showplan"], [["<ShowPlanXML><RelOp>"]]);
+
+    expect(() => parseExplainResult("sqlserver", truncated)).toThrow("Invalid SQL Server ShowPlan XML");
+  });
+
+  it("rejects XML that is not a SHOWPLAN document", () => {
+    const unrelated = result(["XML"], [["<Root><RelOp /></Root>"]]);
+
+    expect(() => parseExplainResult("sqlserver", unrelated)).toThrow("SQL Server did not return ShowPlan XML");
+    expect(sqlServerExplainResult([unrelated])).toEqual({ error: "SQL Server did not return ShowPlan XML" });
+  });
+
+  it("rejects SHOWPLAN XML without RelOp nodes", () => {
+    const emptyPlan = result(["Microsoft SQL Server 2005 XML Showplan"], [[`<ShowPlanXML xmlns="http://schemas.microsoft.com/sqlserver/2004/07/showplan"><BatchSequence /></ShowPlanXML>`]]);
+
+    expect(() => parseExplainResult("sqlserver", emptyPlan)).toThrow("SQL Server ShowPlan XML contains no RelOp nodes");
+  });
+});
diff --git a/apps/desktop/src/lib/backend/http.ts b/apps/desktop/src/lib/backend/http.ts
index 230022278..59b13b340 100644
--- a/apps/desktop/src/lib/backend/http.ts
+++ b/apps/desktop/src/lib/backend/http.ts
@@ -712,6 +712,7 @@ export async function executeQuery(
     resultSessionId?: string;
     clientSessionId?: string;
     timeoutSecs?: number;
+    executionMode?: "simple";
   },
 ): Promise<QueryResult> {
   return post("/api/query/execute", { connectionId, database, sql, schema, executionId, ...options });
@@ -732,6 +733,7 @@ export async function executeMulti(
     timeoutSecs?: number;
     useTransaction?: boolean;
     continueOnError?: boolean;
+    executionMode?: "simple";
   },
 ): Promise<QueryResult[]> {
   return post("/api/query/execute-multi", { connectionId, database, sql, schema, executionId, ...options });
diff --git a/apps/desktop/src/lib/backend/tauri.ts b/apps/desktop/src/lib/backend/tauri.ts
index 21d676813..8d1f72afe 100644
--- a/apps/desktop/src/lib/backend/tauri.ts
+++ b/apps/desktop/src/lib/backend/tauri.ts
@@ -780,6 +780,7 @@ export async function executeQuery(
     resultSessionId?: string;
     clientSessionId?: string;
     timeoutSecs?: number;
+    executionMode?: "simple";
   },
 ): Promise<QueryResult> {
   return invoke("execute_query", { connectionId, database, sql, schema, executionId, ...options });
@@ -800,6 +801,7 @@ export async function executeMulti(
     timeoutSecs?: number;
     useTransaction?: boolean;
     continueOnError?: boolean;
+    executionMode?: "simple";
   },
 ): Promise<QueryResult[]> {
   return invoke("execute_multi", { connectionId, database, sql, schema, executionId, ...options });
diff --git a/apps/desktop/src/lib/diagram/explainPlan.ts b/apps/desktop/src/lib/diagram/explainPlan.ts
index 136c48f7b..96941715e 100644
--- a/apps/desktop/src/lib/diagram/explainPlan.ts
+++ b/apps/desktop/src/lib/diagram/explainPlan.ts
@@ -16,15 +16,15 @@ export interface ExplainPlanNode {
 }
 
 export interface ParsedExplainPlan {
-  databaseType: "mysql" | "postgres" | "dameng" | "questdb" | "oracle";
+  databaseType: "mysql" | "postgres" | "dameng" | "questdb" | "oracle" | "sqlserver";
   raw: unknown;
   nodes: ExplainPlanNode[];
 }
 
 export type BuildExplainSqlResult = { ok: true; sql: string } | { ok: false; reason: "unsupported" | "empty" | "unsafe" };
 
-const SUPPORTED_EXPLAIN_TYPES = new Set<DatabaseType>(["mysql", "postgres", "dameng", "questdb", "oracle"]);
-export function supportsExplainPlan(databaseType?: DatabaseType): databaseType is "mysql" | "postgres" | "dameng" | "questdb" | "oracle" {
+const SUPPORTED_EXPLAIN_TYPES = new Set<DatabaseType>(["mysql", "postgres", "dameng", "questdb", "oracle", "sqlserver"]);
+export function supportsExplainPlan(databaseType?: DatabaseType): databaseType is "mysql" | "postgres" | "dameng" | "questdb" | "oracle" | "sqlserver" {
   return !!databaseType && supportsDatabaseFeature(databaseType, "sqlExplain") && SUPPORTED_EXPLAIN_TYPES.has(databaseType);
 }
 
@@ -32,11 +32,13 @@ export function buildExplainSql(databaseType: DatabaseType | undefined, sql: str
   return api.buildExplainSql({ databaseType, sql, format }) as Promise<BuildExplainSqlResult>;
 }
 
-export function parseExplainResult(databaseType: "mysql" | "postgres" | "dameng" | "questdb", result: QueryResult): ParsedExplainPlan {
+export function parseExplainResult(databaseType: "mysql" | "postgres" | "dameng" | "questdb" | "sqlserver", result: QueryResult): ParsedExplainPlan {
   if (databaseType === "dameng") {
     return parseDamengExplain(result);
   } else if (databaseType === "questdb") {
     return parseQuestdbExplain(result);
+  } else if (databaseType === "sqlserver") {
+    return parseSqlServerExplain(result);
   }
   const raw = parseExplainCell(result.rows[0]?.[0]);
   const nodes = databaseType === "postgres" ? parsePostgresExplain(raw) : parseMysqlExplain(raw);
@@ -373,6 +375,138 @@ export function flattenExplainPlanNodes(nodes: ExplainPlanNode[]): ExplainPlanNo
   return rows;
 }
 
+export function sqlServerExplainResult(results: QueryResult[]): { result?: QueryResult; error?: string } {
+  const errorResult = results.find((result) => result.columns.length === 1 && result.columns[0] === "Error" && result.rows.length > 0);
+  if (errorResult) return { error: String(errorResult.rows[0]?.[0] ?? "") };
+
+  const result = results.find((candidate) => firstSqlServerShowplanXml(candidate) !== undefined);
+  return result ? { result } : { error: "SQL Server did not return ShowPlan XML" };
+}
+
+function parseSqlServerExplain(result: QueryResult): ParsedExplainPlan {
+  const raw = firstSqlServerShowplanXml(result);
+  if (!raw) throw new Error("SQL Server did not return ShowPlan XML");
+  if (typeof DOMParser === "undefined") throw new Error("XML parser is unavailable");
+
+  const parserIssues: string[] = [];
+  type XmlParserConstructor = new (options?: {
+    errorHandler?: {
+      warning: (message: string) => void;
+      error: (message: string) => void;
+      fatalError: (message: string) => void;
+    };
+  }) => DOMParser;
+  const Parser = DOMParser as unknown as XmlParserConstructor;
+  const recordParserIssue = (message: string) => parserIssues.push(message);
+  const document = new Parser({
+    errorHandler: {
+      warning: recordParserIssue,
+      error: recordParserIssue,
+      fatalError: recordParserIssue,
+    },
+  }).parseFromString(raw, "application/xml");
+  if (parserIssues.length > 0 || xmlElements(document, "parsererror").length > 0 || !document.documentElement) {
+    throw new Error("Invalid SQL Server ShowPlan XML");
+  }
+
+  const rootName = document.documentElement.localName || document.documentElement.nodeName.split(":").pop();
+  if (rootName !== "ShowPlanXML") throw new Error("Invalid SQL Server ShowPlan XML root element");
+
+  const relOps = xmlElements(document, "RelOp");
+  if (relOps.length === 0) throw new Error("SQL Server ShowPlan XML contains no RelOp nodes");
+  const roots = relOps.filter((element) => !hasRelOpAncestor(element));
+  if (roots.length === 0) throw new Error("SQL Server ShowPlan XML contains no root RelOp node");
+  return {
+    databaseType: "sqlserver",
+    raw,
+    nodes: roots.map(parseSqlServerRelOp),
+  };
+}
+
+function firstSqlServerShowplanXml(result: QueryResult): string | undefined {
+  for (const row of result.rows) {
+    for (const cell of row) {
+      if (typeof cell === "string" && cell.includes("<ShowPlanXML")) return cell;
+    }
+  }
+  return undefined;
+}
+
+function parseSqlServerRelOp(element: Element): ExplainPlanNode {
+  const nodeType = element.getAttribute("PhysicalOp") || element.getAttribute("LogicalOp") || "Plan";
+  const logicalOp = element.getAttribute("LogicalOp") || undefined;
+  const object = planRegionElements(element, "Object")[0];
+  const schema = sqlServerIdentifier(object?.getAttribute("Schema"));
+  const table = sqlServerIdentifier(object?.getAttribute("Table"));
+  const relation = table ? [schema, table].filter(Boolean).join(".") : undefined;
+  const index = sqlServerIdentifier(object?.getAttribute("Index"));
+  const expressions = [
+    ...new Set(
+      planRegionElements(element, "ScalarOperator")
+        .map((operator) => operator.getAttribute("ScalarString")?.trim())
+        .filter((value): value is string => !!value),
+    ),
+  ];
+  const details = [
+    logicalOp && logicalOp !== nodeType ? `Logical: ${logicalOp}` : "",
+    element.getAttribute("EstimatedRowsRead") ? `Estimated Rows Read: ${element.getAttribute("EstimatedRowsRead")}` : "",
+    element.getAttribute("EstimateIO") ? `Estimated I/O: ${element.getAttribute("EstimateIO")}` : "",
+    element.getAttribute("EstimateCPU") ? `Estimated CPU: ${element.getAttribute("EstimateCPU")}` : "",
+    ...expressions.slice(0, 3).map((expression) => `Expression: ${expression}`),
+  ].filter(Boolean);
+
+  return {
+    id: element.getAttribute("NodeId") || "0",
+    title: relation ? `${nodeType} on ${relation}` : nodeType,
+    nodeType,
+    relation,
+    index,
+    cost: element.getAttribute("EstimatedTotalSubtreeCost") || undefined,
+    rows: element.getAttribute("EstimateRows") || undefined,
+    width: element.getAttribute("AvgRowSize") || undefined,
+    details,
+    children: planRegionElements(element, "RelOp").map(parseSqlServerRelOp),
+  };
+}
+
+function planRegionElements(root: Element, localName: string): Element[] {
+  const matches: Element[] = [];
+  const visit = (element: Element) => {
+    for (const child of elementChildren(element)) {
+      if (child.localName === "RelOp") {
+        if (localName === "RelOp") matches.push(child);
+        continue;
+      }
+      if (child.localName === localName) matches.push(child);
+      visit(child);
+    }
+  };
+  visit(root);
+  return matches;
+}
+
+function xmlElements(root: Document | Element, localName: string): Element[] {
+  return Array.from(root.getElementsByTagNameNS("*", localName));
+}
+
+function hasRelOpAncestor(element: Element): boolean {
+  let parent = element.parentNode;
+  while (parent) {
+    if (parent.nodeType === 1 && (parent as Element).localName === "RelOp") return true;
+    parent = parent.parentNode;
+  }
+  return false;
+}
+
+function elementChildren(element: Element): Element[] {
+  return Array.from(element.childNodes).filter((node): node is Element => node.nodeType === 1);
+}
+
+function sqlServerIdentifier(value: string | null | undefined): string | undefined {
+  if (!value) return undefined;
+  return value.startsWith("[") && value.endsWith("]") ? value.slice(1, -1).replaceAll("]]", "]") : value;
+}
+
 function parseExplainCell(value: unknown): unknown {
   if (typeof value !== "string") return value;
   try {
diff --git a/apps/desktop/src/stores/__tests__/queryStore.sqlserverExplain.spec.ts b/apps/desktop/src/stores/__tests__/queryStore.sqlserverExplain.spec.ts
new file mode 100644
index 000000000..b53b9b68e
--- /dev/null
+++ b/apps/desktop/src/stores/__tests__/queryStore.sqlserverExplain.spec.ts
@@ -0,0 +1,146 @@
+import { createPinia, setActivePinia } from "pinia";
+import { beforeEach, describe, expect, it, vi } from "vitest";
+import type { ParsedExplainPlan } from "@/lib/diagram/explainPlan";
+import type { QueryResult } from "@/types/database";
+
+const mocks = vi.hoisted(() => ({
+  buildExplainSql: vi.fn(),
+  parseExplainResult: vi.fn(),
+  sqlServerExplainResult: vi.fn(),
+  executeQuery: vi.fn(),
+  executeMulti: vi.fn(),
+  closeClientConnectionSession: vi.fn(),
+  saveOpenTabsState: vi.fn(),
+  getConfig: vi.fn(),
+}));
+
+vi.mock("@/lib/diagram/explainPlan", () => ({
+  buildExplainSql: mocks.buildExplainSql,
+  parseExplainResult: mocks.parseExplainResult,
+  parseDamengExplainText: vi.fn(),
+  parseOracleExplainText: vi.fn(),
+  sqlServerExplainResult: mocks.sqlServerExplainResult,
+}));
+
+vi.mock("@/lib/backend/api", () => ({
+  executeQuery: mocks.executeQuery,
+  executeMulti: mocks.executeMulti,
+  closeClientConnectionSession: mocks.closeClientConnectionSession,
+  saveOpenTabsState: mocks.saveOpenTabsState,
+}));
+
+vi.mock("@/stores/connectionStore", () => ({
+  useConnectionStore: () => ({
+    getConfig: mocks.getConfig,
+    recordConnectionLostError: vi.fn(),
+  }),
+}));
+
+vi.mock("@/stores/settingsStore", () => ({
+  useSettingsStore: () => ({
+    editorSettings: { pageSize: 100, openTabsRestoreMode: "all", confirmUnsavedSqlClose: false },
+  }),
+}));
+
+const sourceSql = "SELECT * FROM dbo.orders WHERE status = 'paid'";
+const explainSql = `SET SHOWPLAN_XML ON;
+GO
+${sourceSql}
+GO
+SET SHOWPLAN_XML OFF;`;
+const planResult: QueryResult = {
+  columns: ["Microsoft SQL Server 2005 XML Showplan"],
+  rows: [["<ShowPlanXML />"]],
+  affected_rows: 0,
+  execution_time_ms: 2,
+};
+const visualPlan: ParsedExplainPlan = { databaseType: "sqlserver", raw: "<ShowPlanXML />", nodes: [] };
+
+function installLocalStorage() {
+  const data = new Map<string, string>();
+  vi.stubGlobal("localStorage", {
+    getItem: vi.fn((key: string) => data.get(key) ?? null),
+    setItem: vi.fn((key: string, value: string) => data.set(key, value)),
+    removeItem: vi.fn((key: string) => data.delete(key)),
+  });
+}
+
+describe("queryStore SQL Server explain", () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+    vi.unstubAllGlobals();
+    installLocalStorage();
+    setActivePinia(createPinia());
+    mocks.getConfig.mockReturnValue({ id: "sqlserver-1", db_type: "sqlserver", query_timeout_secs: 45 });
+    mocks.buildExplainSql.mockResolvedValue({ ok: true, sql: explainSql });
+    mocks.executeQuery.mockResolvedValue({ columns: [], rows: [], affected_rows: 0, execution_time_ms: 1 });
+    mocks.executeMulti.mockResolvedValue([planResult]);
+    mocks.sqlServerExplainResult.mockReturnValue({ result: planResult });
+    mocks.parseExplainResult.mockReturnValue(visualPlan);
+    mocks.closeClientConnectionSession.mockResolvedValue(true);
+    mocks.saveOpenTabsState.mockResolvedValue(undefined);
+  });
+
+  it("executes all SHOWPLAN batches in an isolated session and closes it", async () => {
+    const { useQueryStore } = await import("@/stores/queryStore");
+    const store = useQueryStore();
+    const tabId = store.createTab("sqlserver-1", "dbx_explain_plan_test", "Query", "query", "dbo");
+
+    await store.explainTabSql(tabId, sourceSql, "sqlserver");
+
+    const enableCall = mocks.executeQuery.mock.calls[0]!;
+    const planCall = mocks.executeMulti.mock.calls[0]!;
+    const disableCall = mocks.executeQuery.mock.calls[1]!;
+    const executionId = enableCall[4] as string;
+    const clientSessionId = enableCall[5].clientSessionId as string;
+    const tab = store.tabs.find((item) => item.id === tabId)!;
+    expect(enableCall.slice(0, 4)).toEqual(["sqlserver-1", "dbx_explain_plan_test", "SET SHOWPLAN_XML ON;", "dbo"]);
+    expect(planCall.slice(0, 4)).toEqual(["sqlserver-1", "dbx_explain_plan_test", sourceSql, "dbo"]);
+    expect(disableCall.slice(0, 4)).toEqual(["sqlserver-1", "dbx_explain_plan_test", "SET SHOWPLAN_XML OFF;", "dbo"]);
+    expect(planCall[4]).toBe(executionId);
+    expect(disableCall[4]).toBeUndefined();
+    expect(clientSessionId).toBe(`${tabId}:explain:${executionId}`);
+    expect(enableCall[5]).toMatchObject({ clientSessionId, timeoutSecs: 45, executionMode: "simple" });
+    expect(planCall[5]).toMatchObject({ clientSessionId, timeoutSecs: 45, executionMode: "simple" });
+    expect(disableCall[5]).toMatchObject({ clientSessionId, timeoutSecs: 5, executionMode: "simple" });
+    expect(mocks.parseExplainResult).toHaveBeenCalledWith("sqlserver", planResult);
+    expect(tab.explainPlan).toEqual(visualPlan);
+    expect(tab.explainError).toBeUndefined();
+    expect(tab.isExplaining).toBe(false);
+    await vi.waitFor(() => expect(mocks.closeClientConnectionSession).toHaveBeenCalledWith("sqlserver-1", "dbx_explain_plan_test", clientSessionId));
+  });
+
+  it("shows an execution error and still closes the SHOWPLAN session", async () => {
+    mocks.sqlServerExplainResult.mockReturnValue({ error: "Invalid object name 'missing_table'" });
+    const { useQueryStore } = await import("@/stores/queryStore");
+    const store = useQueryStore();
+    const tabId = store.createTab("sqlserver-1", "dbx_explain_plan_test", "Query");
+
+    await store.explainTabSql(tabId, sourceSql, "sqlserver");
+
+    const tab = store.tabs.find((item) => item.id === tabId)!;
+    expect(tab.explainPlan).toBeUndefined();
+    expect(tab.explainError).toBe("Invalid object name 'missing_table'");
+    expect(mocks.parseExplainResult).not.toHaveBeenCalled();
+    expect(mocks.executeMulti).toHaveBeenCalledTimes(1);
+    expect(mocks.executeQuery).toHaveBeenCalledTimes(2);
+    expect(mocks.executeQuery.mock.calls[1]?.[2]).toBe("SET SHOWPLAN_XML OFF;");
+    await vi.waitFor(() => expect(mocks.closeClientConnectionSession).toHaveBeenCalledTimes(1));
+  });
+
+  it("does not execute the source SQL when SHOWPLAN cannot be enabled", async () => {
+    mocks.executeQuery.mockReset().mockRejectedValueOnce(new Error("SHOWPLAN permission denied"));
+    const { useQueryStore } = await import("@/stores/queryStore");
+    const store = useQueryStore();
+    const tabId = store.createTab("sqlserver-1", "dbx_explain_plan_test", "Query");
+
+    await store.explainTabSql(tabId, sourceSql, "sqlserver");
+
+    const tab = store.tabs.find((item) => item.id === tabId)!;
+    expect(tab.explainError).toBe("SHOWPLAN permission denied");
+    expect(mocks.executeQuery).toHaveBeenCalledTimes(1);
+    expect(mocks.executeMulti).not.toHaveBeenCalled();
+    expect(mocks.executeQuery.mock.calls[0]?.[2]).toBe("SET SHOWPLAN_XML ON;");
+    await vi.waitFor(() => expect(mocks.closeClientConnectionSession).toHaveBeenCalledTimes(1));
+  });
+});
diff --git a/apps/desktop/src/stores/queryStore.ts b/apps/desktop/src/stores/queryStore.ts
index 0d8c6b188..b03ef3a2b 100644
--- a/apps/desktop/src/stores/queryStore.ts
+++ b/apps/desktop/src/stores/queryStore.ts
@@ -5,7 +5,7 @@ import { useI18n } from "vue-i18n";
 import type { ConnectionConfig, DatabaseType, ObjectBrowserViewport, QueryResult, QueryTab, TableInfoTab, TableStructureEditorTarget } from "@/types/database";
 import { orderPinnedFirst } from "@/lib/app/pinnedItems";
 import { canCancelQueryExecution } from "@/lib/sql/queryExecutionState";
-import { buildExplainSql, parseExplainResult, parseDamengExplainText, parseOracleExplainText, type BuildExplainSqlResult } from "@/lib/diagram/explainPlan";
+import { buildExplainSql, parseExplainResult, parseDamengExplainText, parseOracleExplainText, sqlServerExplainResult, type BuildExplainSqlResult } from "@/lib/diagram/explainPlan";
 import { allEditableColumnsWriteable, allPrimaryKeysPresent, analyzeEditableQueryEditability, resolveMetadataColumnName, sourceColumnsForResult, type EditableQueryInfo, type EditableQuerySource } from "@/lib/sql/sqlAnalysis";
 import { buildQueryWithHiddenPrimaryKeys, hiddenResultColumnIndexes, type HiddenPrimaryKeyProjection } from "@/lib/sql/editableQueryHiddenKeys";
 import { ACTIVE_TAB_STORAGE_KEY, OPEN_TABS_STORAGE_KEY, restoreOpenTabsPayload, restoreOpenTabsState, serializeOpenTabs } from "@/lib/app/openTabsPersistence";
@@ -3619,6 +3619,86 @@ export const useQueryStore = defineStore("query", () => {
       return { ok: true as const, sql: jsonBuilt.sql };
     }
 
+    if (databaseType === "sqlserver") {
+      let built: BuildExplainSqlResult;
+      try {
+        built = await buildExplainSql(databaseType, sql);
+      } catch (e: any) {
+        tab.isExplaining = false;
+        tab.explainExecutionId = undefined;
+        tab.explainError = String(e?.message || e);
+        return { ok: true as const, sql: "" };
+      }
+      if (!built.ok) {
+        tab.isExplaining = false;
+        tab.explainExecutionId = undefined;
+        tab.explainError = built.reason;
+        return built;
+      }
+
+      tab.explainSql = built.sql;
+      const clientSessionId = `${tabClientSessionId(tab, "explain")}:${executionId}`;
+      tab.explainClientSessionId = clientSessionId;
+      let showplanEnabled = false;
+      try {
+        await api.executeQuery(tab.connectionId, tab.database, "SET SHOWPLAN_XML ON;", tab.schema, executionId, {
+          clientSessionId,
+          timeoutSecs: queryTimeoutSecs,
+          executionMode: "simple",
+        });
+        showplanEnabled = true;
+        if (tabs.value.find((t) => t.id === id)?.explainExecutionId !== executionId) {
+          return { ok: true as const, sql: built.sql };
+        }
+
+        const results = await api.executeMulti(tab.connectionId, tab.database, sql, tab.schema, executionId, {
+          clientSessionId,
+          timeoutSecs: queryTimeoutSecs,
+          executionMode: "simple",
+        });
+        const current = tabs.value.find((t) => t.id === id);
+        if (current?.explainExecutionId === executionId) {
+          const outcome = sqlServerExplainResult(results);
+          if (outcome.error !== undefined) {
+            current.explainPlan = undefined;
+            current.explainError = outcome.error;
+          } else if (outcome.result) {
+            current.explainPlan = parseExplainResult("sqlserver", outcome.result);
+            current.explainError = undefined;
+          } else {
+            current.explainPlan = undefined;
+            current.explainError = t("explain.empty");
+          }
+        }
+      } catch (e: any) {
+        const current = tabs.value.find((t) => t.id === id);
+        if (current?.explainExecutionId === executionId) {
+          current.explainPlan = undefined;
+          current.explainError = String(e?.message || e);
+        }
+      } finally {
+        if (showplanEnabled) {
+          try {
+            await api.executeQuery(tab.connectionId, tab.database, "SET SHOWPLAN_XML OFF;", tab.schema, undefined, {
+              clientSessionId,
+              timeoutSecs: queryTimeoutSecs > 0 ? Math.min(queryTimeoutSecs, 5) : 5,
+              executionMode: "simple",
+            });
+          } catch (error) {
+            console.warn("[DBX][sqlserver-explain:cleanup:error]", { tabId: tab.id, error });
+          }
+        }
+        const current = tabs.value.find((t) => t.id === id);
+        if (current?.explainExecutionId === executionId) {
+          current.isExplaining = false;
+          current.explainExecutionId = undefined;
+        }
+        if (current?.explainClientSessionId === clientSessionId) current.explainClientSessionId = undefined;
+        await closeClientSessionId(tab.connectionId, tab.database, clientSessionId, { tabId: tab.id, explainExecutionId: executionId });
+      }
+      return { ok: true as const, sql: built.sql };
+    }
+
     const built = await buildExplainSql(databaseType, sql);
     if (!built.ok) {
       tab.explainPlan = undefined;
diff --git a/apps/desktop/src/types/database.ts b/apps/desktop/src/types/database.ts
index 492723872..f80904fc5 100644
--- a/apps/desktop/src/types/database.ts
+++ b/apps/desktop/src/types/database.ts
@@ -813,7 +813,7 @@ export interface QueryTab {
   executionId?: string;
   isExplaining?: boolean;
   explainExecutionId?: string;
-  /** Per-run connection session for sequential MySQL explain formats. */
+  /** Per-run connection session for explain flows that require session state. */
   explainClientSessionId?: string;
   mode: "data" | "query" | "redis" | "redis-dashboard" | "mongo" | "mongo-gridfs" | "mongo-bucket" | "vector" | "etcd" | "zookeeper" | "mq" | "nacos" | "objects" | "structure" | "users" | "dameng-jobs" | "processlist" | "mysql-dashboard";
   mqTenant?: string;
diff --git a/crates/dbx-core/assets/database-drivers.manifest.json b/crates/dbx-core/assets/database-drivers.manifest.json
index cd3c6b85c..b92732ec9 100644
--- a/crates/dbx-core/assets/database-drivers.manifest.json
+++ b/crates/dbx-core/assets/database-drivers.manifest.json
@@ -261,7 +261,7 @@
         "sqlFileExecution": true,
         "databaseCreate": true,
         "fieldLineage": true,
-        "sqlExplain": false,
+        "sqlExplain": true,
         "userAdmin": false,
         "driverManagement": false
       }
diff --git a/crates/dbx-core/src/db/sqlserver.rs b/crates/dbx-core/src/db/sqlserver.rs
index bdcf91745..09a941041 100644
--- a/crates/dbx-core/src/db/sqlserver.rs
+++ b/crates/dbx-core/src/db/sqlserver.rs
@@ -697,6 +697,9 @@ pub async fn stream_first_result_set(
 }
 
 fn sqlserver_cell_to_json(cell: &ColumnData<'static>) -> serde_json::Value {
+    if let Ok(Some(v)) = <&tiberius::xml::XmlData as FromSql>::from_sql(cell) {
+        return serde_json::Value::String(v.as_ref().to_string());
+    }
     if let Ok(Some(v)) = <&str as FromSql>::from_sql(cell) {
         return serde_json::Value::String(v.to_string());
     }
@@ -1733,6 +1736,20 @@ pub async fn execute_batch_with_max_rows(
             );
         }
     }
+    execute_simple_batch_with_max_rows(client, sql, max_rows).await
+}
+
+/// Execute a SQL Server batch directly through TDS simple-query mode.
+///
+/// This intentionally bypasses result-set type probing and SQL rewriting. It is
+/// required while `SHOWPLAN_XML` is enabled because any probe issued on the same
+/// session is itself affected by SHOWPLAN state.
+pub async fn execute_simple_batch_with_max_rows(
+    client: &mut SqlServerClient,
+    sql: &str,
+    max_rows: Option<usize>,
+) -> Result<Vec<QueryResult>, String> {
+    let start = Instant::now();
     let stream = sqlserver_driver_result(client.simple_query(sql)).await?;
     let mut results = sqlserver_driver_result(collect_result_sets_limited(stream, start, max_rows)).await?;
     for result in &mut results {
@@ -1829,6 +1846,9 @@ fn contains_transaction_control(sql: &str) -> bool {
 
 fn requires_simple_query_batch(sql: &str) -> bool {
     let tokens = first_sql_tokens(sql, 4);
+    if tokens.len() >= 2 && tokens[0].eq_ignore_ascii_case("SET") && tokens[1].eq_ignore_ascii_case("SHOWPLAN_XML") {
+        return true;
+    }
     if tokens.len() >= 2 && tokens[0].eq_ignore_ascii_case("CREATE") && tokens[1].eq_ignore_ascii_case("SCHEMA") {
         return true;
     }
@@ -1904,7 +1924,7 @@ mod tests {
         CompletionAssistantMatchMode, CompletionAssistantObjectKind, CompletionAssistantRequest, QueryResult,
     };
     use chrono::NaiveDate;
-    use std::time::Instant;
+    use std::{borrow::Cow, time::Instant};
     use tiberius::{ColumnData, IntoSql};
 
     #[test]
@@ -1919,6 +1939,18 @@ mod tests {
         );
     }
 
+    #[test]
+    fn sqlserver_xml_cells_are_returned_as_strings() {
+        let cell = ColumnData::Xml(Some(Cow::Owned(tiberius::xml::XmlData::new(
+            "<ShowPlanXML><RelOp NodeId=\"0\" /></ShowPlanXML>",
+        ))));
+
+        assert_eq!(
+            sqlserver_cell_to_json(&cell),
+            serde_json::Value::String("<ShowPlanXML><RelOp NodeId=\"0\" /></ShowPlanXML>".to_string())
+        );
+    }
+
     #[test]
     fn sqlserver_endpoint_keeps_regular_hosts() {
         assert_eq!(
@@ -1982,6 +2014,8 @@ mod tests {
 
     #[test]
     fn sqlserver_module_definitions_require_simple_query_batch() {
+        assert!(requires_simple_query_batch("SET SHOWPLAN_XML ON;"));
+        assert!(requires_simple_query_batch("SET SHOWPLAN_XML OFF;"));
         assert!(requires_simple_query_batch("CREATE SCHEMA [analytics];"));
         assert!(requires_simple_query_batch("CREATE FUNCTION dbo.fn_demo() RETURNS INT AS BEGIN RETURN 1; END;"));
         assert!(requires_simple_query_batch("ALTER PROCEDURE dbo.usp_demo AS SELECT 1;"));
@@ -2055,6 +2089,17 @@ mod tests {
         assert!(!execute_batch.contains("into_results"));
     }
 
+    #[test]
+    fn sqlserver_explicit_simple_batch_bypasses_result_type_probing() {
+        let source = include_str!("sqlserver.rs");
+        let simple_batch = source.split("pub async fn execute_simple_batch_with_max_rows").nth(1).unwrap();
+        let simple_batch = simple_batch.split("fn strip_dbx_sqlserver_row_number_column").next().unwrap();
+
+        assert!(simple_batch.contains("client.simple_query(sql)"));
+        assert!(!simple_batch.contains("sqlserver_unsafe_type_query"));
+        assert!(!simple_batch.contains("describe_sqlserver_result_set"));
+    }
+
     #[test]
     fn sqlserver_index_metadata_sql_avoids_string_agg_for_older_compatibility_levels() {
         let sql = sqlserver_indexes_sql("dbo", "DF_Rule");
diff --git a/crates/dbx-core/src/query.rs b/crates/dbx-core/src/query.rs
index a3b3b4549..fdad151a5 100644
--- a/crates/dbx-core/src/query.rs
+++ b/crates/dbx-core/src/query.rs
@@ -4,7 +4,7 @@ use chrono::{DateTime, Duration as ChronoDuration, NaiveDate, NaiveDateTime, Nai
 use duckdb::types::{TimeUnit, Value, ValueRef};
 use futures::StreamExt;
 use mysql_async::prelude::Queryable;
-use serde::Serialize;
+use serde::{Deserialize, Serialize};
 use sqlparser::ast::{
     visit_relations_mut, Ident, ObjectName, ObjectNamePart, ObjectType, Statement, TableFactor, VisitMut, VisitorMut,
 };
@@ -367,6 +367,14 @@ fn qualifies_unqualified_agent_relations(db_type: Option<DatabaseType>) -> bool
     matches!(db_type, Some(DatabaseType::Iris | DatabaseType::Kingbase))
 }
 
+#[derive(Clone, Copy, Debug, Default, Deserialize, PartialEq, Eq)]
+#[serde(rename_all = "snake_case")]
+pub enum QueryExecutionMode {
+    #[default]
+    Standard,
+    Simple,
+}
+
 #[derive(Clone, Debug, Default)]
 pub struct QueryExecutionOptions {
     pub max_rows: Option<usize>,
@@ -385,6 +393,9 @@ pub struct QueryExecutionOptions {
     /// When `true`, multi-statement execution continues after a statement error instead
     /// of stopping at the first failure. Connection-level failures always stop the batch.
     pub continue_on_error: bool,
+    /// Explicit low-level execution path. `Simple` is currently used by SQL Server
+    /// SHOWPLAN so the source SQL bypasses result-set probing and query rewriting.
+    pub execution_mode: QueryExecutionMode,
 }
 
 fn query_result_row_limit(max_rows: Option<usize>) -> usize {
@@ -1405,6 +1416,7 @@ pub async fn do_execute(
         PoolKind::SqlServer(client) => {
             let client = client.clone();
             let max_rows = options.max_rows;
+            let execution_mode = options.execution_mode;
             drop(connections);
             let mut client = match cancel_token.as_ref() {
                 Some(token) => tokio::select! {
@@ -1414,13 +1426,18 @@ pub async fn do_execute(
                 },
                 None => client.lock().await,
             };
-            let result = wait_for_query_opt(
-                cancel_token,
-                query_timeout,
-                db::sqlserver::execute_query_with_max_rows(&mut client, sql, max_rows),
-            )
-            .await
-            .map(|result| truncate_result_with_max_rows(result, max_rows));
+            let execution = async {
+                if execution_mode == QueryExecutionMode::Simple {
+                    let mut results =
+                        db::sqlserver::execute_simple_batch_with_max_rows(&mut client, sql, max_rows).await?;
+                    Ok(results.remove(0))
+                } else {
+                    db::sqlserver::execute_query_with_max_rows(&mut client, sql, max_rows).await
+                }
+            };
+            let result = wait_for_query_opt(cancel_token, query_timeout, execution)
+                .await
+                .map(|result| truncate_result_with_max_rows(result, max_rows));
             drop(client);
             if matches!(result.as_ref(), Err(err) if should_discard_pool_after_error(pool_db_type, err)) {
                 state.remove_pool_by_key(pool_key).await;
@@ -2186,6 +2203,7 @@ async fn execute_multi_sqlserver(
     let mut all_results = Vec::new();
     let max_rows = options.max_rows;
     let query_timeout = resolve_query_timeout(options.timeout_secs);
+    let execution_mode = options.execution_mode;
 
     for batch in &batches {
         if is_canceled(&cancel_token) {
@@ -2226,12 +2244,14 @@ async fn execute_multi_sqlserver(
             break;
         }
 
-        let result = wait_for_result_opt(
-            cancel_token.clone(),
-            query_timeout,
-            db::sqlserver::execute_batch_with_max_rows(&mut client_guard, batch, max_rows),
-        )
-        .await;
+        let execution = async {
+            if execution_mode == QueryExecutionMode::Simple {
+                db::sqlserver::execute_simple_batch_with_max_rows(&mut client_guard, batch, max_rows).await
+            } else {
+                db::sqlserver::execute_batch_with_max_rows(&mut client_guard, batch, max_rows).await
+            }
+        };
+        let result = wait_for_result_opt(cancel_token.clone(), query_timeout, execution).await;
         drop(client_guard);
 
         match result {
@@ -3235,6 +3255,14 @@ mod tests {
     };
     use crate::storage::Storage;
 
+    #[test]
+    fn query_execution_mode_deserializes_simple_client_value() {
+        let mode: QueryExecutionMode = serde_json::from_str("\"simple\"").unwrap();
+
+        assert_eq!(mode, QueryExecutionMode::Simple);
+        assert_eq!(QueryExecutionMode::default(), QueryExecutionMode::Standard);
+    }
+
     fn test_connection_config(db_type: DatabaseType) -> ConnectionConfig {
         ConnectionConfig {
             id: "conn-1".to_string(),
diff --git a/crates/dbx-core/src/query_execution_sql.rs b/crates/dbx-core/src/query_execution_sql.rs
index 5a3350f88..fc1fb3807 100644
--- a/crates/dbx-core/src/query_execution_sql.rs
+++ b/crates/dbx-core/src/query_execution_sql.rs
@@ -53,6 +53,9 @@ pub fn build_explain_sql(options: ExplainSqlOptions) -> ExplainSqlBuildResult {
     if !is_safe_explain_sql(&source) {
         return explain_err("unsafe");
     }
+    if options.database_type == Some(DatabaseType::SqlServer) && crate::sql::split_sql_batches(&source).len() != 1 {
+        return explain_err("unsafe");
+    }
 
     let sql = match options.database_type {
         Some(DatabaseType::Postgres | DatabaseType::MongoDb) => {
@@ -62,6 +65,9 @@ pub fn build_explain_sql(options: ExplainSqlOptions) -> ExplainSqlBuildResult {
             format!("EXPLAIN {source}")
         }
         Some(DatabaseType::Oracle) => format!("EXPLAIN PLAN FOR {source}"),
+        Some(DatabaseType::SqlServer) => {
+            format!("SET SHOWPLAN_XML ON;\nGO\n{source}\nGO\nSET SHOWPLAN_XML OFF;")
+        }
         Some(DatabaseType::Mysql) if options.format == Some(ExplainFormat::Standard) => {
             // MySQL 8.0.32+ may otherwise inherit TREE or JSON from the session-level explain_format.
             format!("EXPLAIN FORMAT=TRADITIONAL {source}")
@@ -99,6 +105,7 @@ pub fn supports_explain_plan(database_type: Option<DatabaseType>) -> bool {
                 | DatabaseType::Questdb
                 | DatabaseType::Dameng
                 | DatabaseType::Oracle
+                | DatabaseType::SqlServer
         )
     )
 }
@@ -202,6 +209,9 @@ pub fn is_write_sql_for_database(sql: &str, database_type: DatabaseType) -> bool
 }
 
 fn is_write_sql_with_database_type(sql: &str, database_type: Option<DatabaseType>) -> bool {
+    if database_type == Some(DatabaseType::SqlServer) && is_sqlserver_showplan_xml_set(sql) {
+        return false;
+    }
     if database_type.is_some_and(|database_type| has_dialect_specific_write(sql, database_type)) {
         return true;
     }
@@ -220,6 +230,14 @@ fn is_write_sql_with_database_type(sql: &str, database_type: Option<DatabaseType
         .any(|statement| is_write_sql_statement(statement, detect_mysql_executable_comments, detect_select_into))
 }
 
+fn is_sqlserver_showplan_xml_set(sql: &str) -> bool {
+    let normalized = strip_sql_comments(sql)
+        .split_whitespace()
+        .map(|part| part.trim_end_matches(';').to_ascii_uppercase())
+        .collect::<Vec<_>>();
+    matches!(normalized.as_slice(), [set, showplan, value] if set == "SET" && showplan == "SHOWPLAN_XML" && matches!(value.as_str(), "ON" | "OFF"))
+}
+
 fn is_mysql_compatible_database(database_type: DatabaseType) -> bool {
     matches!(
         database_type,
@@ -716,6 +734,44 @@ mod tests {
         );
     }
 
+    #[test]
+    fn builds_sqlserver_showplan_xml_batches() {
+        let result = build_explain_sql(ExplainSqlOptions {
+            database_type: Some(DatabaseType::SqlServer),
+            format: None,
+            sql: "WITH rows AS (SELECT 1 AS id) SELECT * FROM rows;".to_string(),
+        });
+
+        assert_eq!(
+            result,
+            ExplainSqlBuildResult {
+                ok: true,
+                sql: Some(
+                    "SET SHOWPLAN_XML ON;\nGO\nWITH rows AS (SELECT 1 AS id) SELECT * FROM rows\nGO\nSET SHOWPLAN_XML OFF;"
+                        .to_string()
+                ),
+                reason: None,
+            }
+        );
+
+        assert_eq!(
+            build_explain_sql(ExplainSqlOptions {
+                database_type: Some(DatabaseType::SqlServer),
+                format: None,
+                sql: "SELECT 1\nGO\nSELECT 2".to_string(),
+            }),
+            ExplainSqlBuildResult { ok: false, sql: None, reason: Some("unsafe".to_string()) }
+        );
+        assert!(
+            build_explain_sql(ExplainSqlOptions {
+                database_type: Some(DatabaseType::SqlServer),
+                format: None,
+                sql: "SELECT 'first line\nGO\nlast line' AS text".to_string(),
+            })
+            .ok
+        );
+    }
+
     #[test]
     fn validates_dameng_autotrace_sql_safety() {
         assert!(is_safe_dameng_autotrace_sql("SELECT * FROM t WHERE name = 'delete';"));
@@ -1144,6 +1200,16 @@ mod tests {
         assert!(show_create_err.unwrap_err().contains("Write operation"));
     }
 
+    #[test]
+    fn check_read_only_allows_only_sqlserver_showplan_xml_session_switches() {
+        for sql in ["SET SHOWPLAN_XML ON;", "-- explain\nSET SHOWPLAN_XML OFF"] {
+            assert_eq!(check_read_only(sql, "readonly", DatabaseType::SqlServer), Ok(()));
+        }
+        assert!(check_read_only("SET SHOWPLAN_ALL ON", "readonly", DatabaseType::SqlServer).is_err());
+        assert!(check_read_only("SET SHOWPLAN_XML ON; SELECT 1", "readonly", DatabaseType::SqlServer).is_err());
+        assert!(check_read_only("SET SHOWPLAN_XML OFF; DROP TABLE users", "readonly", DatabaseType::SqlServer).is_err());
+    }
+
     #[test]
     fn check_read_only_only_treats_executable_comments_as_writes_for_mysql_compatible_connections() {
         let mysql_executable_comment = "SELECT 3156 /*!50000 INTO OUTFILE '/var/lib/mysql-files/dbx_ro_probe.txt' */";
diff --git a/crates/dbx-web/src/routes/query.rs b/crates/dbx-web/src/routes/query.rs
index d037c9c42..2e3d6eccb 100644
--- a/crates/dbx-web/src/routes/query.rs
+++ b/crates/dbx-web/src/routes/query.rs
@@ -24,6 +24,7 @@ pub struct ExecuteQueryRequest {
     pub timeout_secs: Option<u64>,
     pub use_transaction: Option<bool>,
     pub continue_on_error: Option<bool>,
+    pub execution_mode: Option<dbx_core::query::QueryExecutionMode>,
 }
 
 #[derive(Deserialize)]
@@ -335,6 +336,7 @@ pub async fn execute_query(
             timeout_secs: req.timeout_secs,
             execution_id: Some(execution_id),
             use_transaction: req.use_transaction,
+            execution_mode: req.execution_mode.unwrap_or_default(),
             ..Default::default()
         },
     )
@@ -374,6 +376,7 @@ pub async fn execute_multi(
             execution_id: Some(execution_id),
             use_transaction: req.use_transaction,
             continue_on_error: req.continue_on_error.unwrap_or(false),
+            execution_mode: req.execution_mode.unwrap_or_default(),
         },
     )
     .await
diff --git a/package.json b/package.json
index 6789e5e88..eccdb618f 100644
--- a/package.json
+++ b/package.json
@@ -96,6 +96,7 @@
     "@types/node": "^25.9.1",
     "@types/splitpanes": "^2.2.6",
     "@vitejs/plugin-vue": "^6.0.7",
+    "@xmldom/xmldom": "^0.8.13",
     "happy-dom": "^20.10.6",
     "husky": "^9.1.7",
     "lint-staged": "^16.4.0",
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index d32420e3a..70b57e94f 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -192,6 +192,9 @@ importers:
       '@vitejs/plugin-vue':
         specifier: ^6.0.7
         version: 6.0.7(vite@8.0.16(@types/node@25.9.1)(esbuild@0.28.0)(jiti@2.7.0)(stylus@0.57.0)(tsx@4.22.4)(yaml@2.8.4))(vue@3.5.35(typescript@6.0.3))
+      '@xmldom/xmldom':
+        specifier: ^0.8.13
+        version: 0.8.13
       happy-dom:
         specifier: ^20.10.6
         version: 20.10.6
@@ -1805,6 +1808,10 @@ packages:
     peerDependencies:
       vue: ^3.5.0
 
+  '@xmldom/xmldom@0.8.13':
+    resolution: {integrity: sha512-KRYzxepc14G/CEpEGc3Yn+JKaAeT63smlDr+vjB8jRfgTBBI9wRj/nkQEO+ucV8p8I9bfKLWp37uHgFrbntPvw==}
+    engines: {node: '>=10.0.0'}
+
   accepts@2.0.0:
     resolution: {integrity: sha512-5cvg6CtKwfgdmVqY1WIiXKc3Q1bkRqGLi+2W/6ao+6Y7gu/RCwRuAhGEzh5B4KlszSuTLgZYuqFqo5bImjNKng==}
     engines: {node: '>= 0.6'}
@@ -5588,6 +5595,8 @@ snapshots:
     dependencies:
       vue: 3.5.35(typescript@6.0.3)
 
+  '@xmldom/xmldom@0.8.13': {}
+
   accepts@2.0.0:
     dependencies:
       mime-types: 3.0.2
diff --git a/src-tauri/src/commands/query.rs b/src-tauri/src/commands/query.rs
index b8e69f678..2f0fd693e 100644
--- a/src-tauri/src/commands/query.rs
+++ b/src-tauri/src/commands/query.rs
@@ -23,6 +23,7 @@ pub async fn execute_query(
     result_session_id: Option<String>,
     client_session_id: Option<String>,
     timeout_secs: Option<u64>,
+    execution_mode: Option<dbx_core::query::QueryExecutionMode>,
 ) -> Result<db::QueryResult, String> {
     let execution_id = execution_id.filter(|id| !id.trim().is_empty());
     let registered_query = execution_id.as_ref().map(|id| {
@@ -48,6 +49,7 @@ pub async fn execute_query(
             client_session_id,
             timeout_secs,
             execution_id,
+            execution_mode: execution_mode.unwrap_or_default(),
             ..Default::default()
         },
     )
@@ -71,6 +73,7 @@ pub async fn execute_multi(
     timeout_secs: Option<u64>,
     use_transaction: Option<bool>,
     continue_on_error: Option<bool>,
+    execution_mode: Option<dbx_core::query::QueryExecutionMode>,
 ) -> Result<Vec<dbx_core::query::ExecuteMultiResult>, String> {
     let execution_id = execution_id.filter(|id| !id.trim().is_empty());
     let registered_query = execution_id.as_ref().map(|id| {
@@ -108,6 +111,7 @@ pub async fn execute_multi(
             execution_id,
             use_transaction,
             continue_on_error: continue_on_error.unwrap_or(false),
+            execution_mode: execution_mode.unwrap_or_default(),
         },
     )
     .await;