perf(sqlite): eliminate redundant double string conversion pass in SqliteSqlExecutionDelegate

lib/features/sqlite/sqlite_result_utils.dart

@@ -1,29 +1,72 @@
-import 'dart:typed_data';
-
+import 'package:flutter/foundation.dart';
+import 'package:querya_desktop/core/database/result_row_string_convert.dart';
 import 'package:querya_desktop/core/database/table_mutation_engine.dart';
 
 /// Serializable row batch for [convertSqliteResultRowsToStrings] in a worker isolate.
 class SqliteResultConvertJob {
   const SqliteResultConvertJob({
     required this.rowValues,
+    this.columnDataTypes,
   });
 
   final List<List<Object?>> rowValues;
+  final List<String?>? columnDataTypes;
 }
 
 /// Converts SQLite result cell values to display strings off the UI thread.
 List<List<String>> convertSqliteResultRowsToStrings(
     SqliteResultConvertJob job) {
+  final types = job.columnDataTypes;
   return [
     for (final row in job.rowValues)
-      [for (final value in row) sqliteResultCellToDisplayString(value)],
+      [
+        for (var i = 0; i < row.length; i++)
+          sqliteResultCellToDisplayString(
+            row[i],
+            dataTypeName: types != null && i < types.length ? types[i] : null,
+          ),
+      ],
   ];
 }
 
+/// Typed conversion in a single pass: converts each cell to SQLite display string,
+/// interns the resulting string (repeated values share one instance), and yields
+/// to the event loop every [yieldEvery] rows.
+Future<List<List<String>>> convertSqliteResultRowsToStringsAdaptive(
+  SqliteResultConvertJob job, {
+  int yieldEvery = kResultStringConvertYieldEvery,
+  StringInternPool? pool,
+}) async {
+  final rowValues = job.rowValues;
+  if (rowValues.isEmpty) return const [];
+
+  final types = job.columnDataTypes;
+  final activePool = pool ?? StringInternPool();
+  final out = <List<String>>[];
+  for (var r = 0; r < rowValues.length; r++) {
+    final row = rowValues[r];
+    out.add([
+      for (var i = 0; i < row.length; i++)
+        activePool.intern(
+          sqliteResultCellToDisplayString(
+            row[i],
+            dataTypeName: types != null && i < types.length ? types[i] : null,
+            pool: activePool,
+          ),
+        ),
+    ]);
+    if (yieldEvery > 0 && (r + 1) % yieldEvery == 0) {
+      await Future<void>.delayed(Duration.zero);
+    }
+  }
+  return out;
+}
+
 /// BLOB as `X'deadbeef'`; other values via [Object.toString]. Null → `NULL`.
 String sqliteResultCellToDisplayString(
   Object? value, {
   String? dataTypeName,
+  StringInternPool? pool,
 }) {
   if (value == null) return 'NULL';
   if (value is Uint8List) {
@@ -37,6 +80,10 @@ String sqliteResultCellToDisplayString(
       TableMutationEngine.isBinaryType(dataTypeName)) {
     return sqliteBlobHexLiteralFromCell(value);
   }
+  if (pool != null) {
+    return pool.internObject(value);
+  }
+  if (value is bool) return value ? 'true' : 'false';
   return value.toString();
 }
 

lib/features/sqlite/sqlite_sql_workspace.dart

@@ -1,7 +1,6 @@
 import 'dart:async';
 
 import 'package:flutter/material.dart' as material;
-import 'package:querya_desktop/core/database/result_row_string_convert.dart';
 import 'package:querya_desktop/core/database/sql_limit.dart';
 import 'package:querya_desktop/core/database/sql_table_target_extractor.dart';
 import 'package:querya_desktop/core/database/sqlite_service.dart';
@@ -105,13 +104,17 @@ class SqliteSqlExecutionDelegate extends BaseSqlExecutionDelegate {
     final limitCount = truncated ? cap : results.length;
     final injectedLimit = effectiveSql != sql;
 
-    final rawRows = results.take(limitCount).map((row) {
-      return cols
-          .map((col) => sqliteResultCellToDisplayString(row[col]))
-          .toList();
-    }).toList();
+    final rawRows = <List<Object?>>[];
+    var count = 0;
+    for (final row in results) {
+      if (count >= limitCount) break;
+      rawRows.add([for (final col in cols) row[col]]);
+      count++;
+    }
 
-    final outRows = await convertResultRowsToStringsAdaptive(rawRows);
+    final outRows = await convertSqliteResultRowsToStringsAdaptive(
+      SqliteResultConvertJob(rowValues: rawRows),
+    );
 
     final isTruncated = truncated || (injectedLimit && results.length >= cap);
     final statusMsg = formatStatusMessage(

test/features/sql_workspaces/result_conversion_perf_test.dart

@@ -156,4 +156,57 @@ void main() {
       expect(ticks, 1, reason: 'a queued task ran while conversion was in flight');
     });
   });
+
+  group('convertSqliteResultRowsToStringsAdaptive (single typed pass)', () {
+    List<List<Object?>> sample(int n) => [
+          for (var i = 0; i < n; i++)
+            [
+              i,
+              i.isEven ? 'active' : 'custom_$i',
+              i % 3 == 0 ? Uint8List.fromList([0xca, 0xfe]) : null,
+              null,
+            ],
+        ];
+
+    test('matches synchronous convertSqliteResultRowsToStrings', () async {
+      final job = SqliteResultConvertJob(rowValues: sample(1200));
+      expect(
+        await convertSqliteResultRowsToStringsAdaptive(job),
+        convertSqliteResultRowsToStrings(job),
+      );
+    });
+
+    test('interns repeated values so they share one string instance', () async {
+      final out = await convertSqliteResultRowsToStringsAdaptive(
+        SqliteResultConvertJob(
+          rowValues: [
+            for (var i = 0; i < 6; i++) [i, 'status_${i % 2}_${'x' * 4}'],
+          ],
+        ),
+      );
+      expect(identical(out[0][1], out[2][1]), isTrue);
+      expect(identical(out[1][1], out[3][1]), isTrue);
+    });
+
+    test('empty input yields empty output', () async {
+      expect(
+        await convertSqliteResultRowsToStringsAdaptive(
+          const SqliteResultConvertJob(rowValues: []),
+        ),
+        isEmpty,
+      );
+    });
+
+    test('formats blobs correctly as hex literals in adaptive mode', () async {
+      final out = await convertSqliteResultRowsToStringsAdaptive(
+        SqliteResultConvertJob(
+          rowValues: [
+            ['ok', Uint8List.fromList([0xde, 0xad]), null],
+          ],
+        ),
+      );
+      expect(out.single, ['ok', "X'dead'", 'NULL']);
+    });
+  });
 }
+