Skip exact COUNT(*) for large tables, use database statistics estimate

CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Fix macOS HIG compliance: system colors, accessibility labels, theme tokens, localization
 - Fix idle ping spin loop caused by exhausted AsyncStream iterator (#618)
+- Skip exact row count for large tables — use database statistics estimate (#519)
 
 ## [0.28.0] - 2026-04-07
 

TablePro/Models/Settings/AppSettings.swift

@@ -122,6 +122,7 @@ struct DataGridSettings: Codable, Equatable {
     var showRowNumbers: Bool
     var autoShowInspector: Bool
     var enableSmartValueDetection: Bool
+    var countRowsIfEstimateLessThan: Int
 
     static let `default` = DataGridSettings(
         rowHeight: .normal,
@@ -131,7 +132,8 @@ struct DataGridSettings: Codable, Equatable {
         showAlternateRows: true,
         showRowNumbers: true,
         autoShowInspector: false,
-        enableSmartValueDetection: true
+        enableSmartValueDetection: true,
+        countRowsIfEstimateLessThan: 100_000
     )
 
     init(
@@ -142,7 +144,8 @@ struct DataGridSettings: Codable, Equatable {
         showAlternateRows: Bool = true,
         showRowNumbers: Bool = true,
         autoShowInspector: Bool = false,
-        enableSmartValueDetection: Bool = true
+        enableSmartValueDetection: Bool = true,
+        countRowsIfEstimateLessThan: Int = 100_000
     ) {
         self.rowHeight = rowHeight
         self.dateFormat = dateFormat
@@ -152,6 +155,7 @@ struct DataGridSettings: Codable, Equatable {
         self.showRowNumbers = showRowNumbers
         self.autoShowInspector = autoShowInspector
         self.enableSmartValueDetection = enableSmartValueDetection
+        self.countRowsIfEstimateLessThan = countRowsIfEstimateLessThan
     }
 
     init(from decoder: Decoder) throws {
@@ -165,6 +169,7 @@ struct DataGridSettings: Codable, Equatable {
         showRowNumbers = try container.decodeIfPresent(Bool.self, forKey: .showRowNumbers) ?? true
         autoShowInspector = try container.decodeIfPresent(Bool.self, forKey: .autoShowInspector) ?? false
         enableSmartValueDetection = try container.decodeIfPresent(Bool.self, forKey: .enableSmartValueDetection) ?? true
+        countRowsIfEstimateLessThan = try container.decodeIfPresent(Int.self, forKey: .countRowsIfEstimateLessThan) ?? 100_000
     }
 
     // MARK: - Validated Properties

TablePro/Views/Main/Extensions/MainContentCoordinator+QueryHelpers.swift

@@ -253,9 +253,23 @@ extension MainContentCoordinator {
             guard let mainDriver = DatabaseManager.shared.driver(for: connectionId) else { return }
 
             let count: Int?
+            let isApproximate: Bool
             if isNonSQL {
                 count = try? await mainDriver.fetchApproximateRowCount(table: tableName)
+                isApproximate = true
             } else {
+                // Skip exact COUNT(*) if the approximate count exceeds the threshold.
+                // PostgreSQL COUNT(*) requires a full sequential scan (MVCC) and can take
+                // 10-20+ seconds on multi-million-row tables. Industry standard (TablePlus,
+                // pgAdmin, DBeaver) is to use estimates for large tables.
+                let threshold = await AppSettingsManager.shared.dataGrid.countRowsIfEstimateLessThan
+                let approxCount = await MainActor.run {
+                    self.tabManager.tabs.first { $0.id == tabId }?.pagination.totalRowCount
+                }
+                if let approx = approxCount, approx >= threshold {
+                    return // Keep approximate count — skip expensive COUNT(*)
+                }
+
                 let quotedTable = mainDriver.quoteIdentifier(tableName)
                 let countResult = try? await mainDriver.execute(
                     query: "SELECT COUNT(*) FROM \(quotedTable)"
@@ -266,6 +280,7 @@ extension MainContentCoordinator {
                 } else {
                     count = nil
                 }
+                isApproximate = false
             }
 
             if let count {
@@ -274,7 +289,7 @@ extension MainContentCoordinator {
                     guard capturedGeneration == queryGeneration else { return }
                     if let idx = tabManager.tabs.firstIndex(where: { $0.id == tabId }) {
                         tabManager.tabs[idx].pagination.totalRowCount = count
-                        tabManager.tabs[idx].pagination.isApproximateRowCount = isNonSQL
+                        tabManager.tabs[idx].pagination.isApproximateRowCount = isApproximate
                     }
                 }
             }
@@ -346,9 +361,19 @@ extension MainContentCoordinator {
             guard let mainDriver = DatabaseManager.shared.driver(for: connectionId) else { return }
 
             let count: Int?
+            let isApproximate: Bool
             if isNonSQL {
                 count = try? await mainDriver.fetchApproximateRowCount(table: tableName)
+                isApproximate = true
             } else {
+                let threshold = await AppSettingsManager.shared.dataGrid.countRowsIfEstimateLessThan
+                let approxCount = await MainActor.run {
+                    self.tabManager.tabs.first { $0.id == tabId }?.pagination.totalRowCount
+                }
+                if let approx = approxCount, approx >= threshold {
+                    return
+                }
+
                 let quotedTable = mainDriver.quoteIdentifier(tableName)
                 let countResult = try? await mainDriver.execute(
                     query: "SELECT COUNT(*) FROM \(quotedTable)"
@@ -359,14 +384,15 @@ extension MainContentCoordinator {
                 } else {
                     count = nil
                 }
+                isApproximate = false
             }
 
             if let count {
                 await MainActor.run { [weak self] in
                     guard let self else { return }
                     if let idx = tabManager.tabs.firstIndex(where: { $0.id == tabId }) {
                         tabManager.tabs[idx].pagination.totalRowCount = count
-                        tabManager.tabs[idx].pagination.isApproximateRowCount = isNonSQL
+                        tabManager.tabs[idx].pagination.isApproximateRowCount = isApproximate
                     }
                 }
             }

TablePro/Views/Settings/DataGridSettingsView.swift

@@ -56,6 +56,15 @@ struct DataGridSettingsView: View {
                     Text("5,000 rows").tag(5_000)
                     Text("10,000 rows").tag(10_000)
                 }
+
+                Picker(String(localized: "Count rows if estimate less than:"), selection: $settings.countRowsIfEstimateLessThan) {
+                    Text("1,000").tag(1_000)
+                    Text("10,000").tag(10_000)
+                    Text("100,000").tag(100_000)
+                    Text("1,000,000").tag(1_000_000)
+                    Text(String(localized: "Always count")).tag(Int.max)
+                }
+                .help(String(localized: "Tables with more estimated rows use approximate counts to avoid slow COUNT(*) queries"))
             }
         }
         .formStyle(.grouped)

docs/customization/settings.mdx

@@ -210,6 +210,14 @@ Options:
 Larger page sizes use more memory but show more data at once.
 </Note>
 
+### Row Count Estimation
+
+| Setting | Options | Default |
+|---------|---------|---------|
+| Count rows if estimate less than | 1,000 / 10,000 / 100,000 / 1,000,000 / Always count | 100,000 |
+
+Tables above this threshold show an estimated count (`~3,000,000 rows`) from database statistics instead of running `COUNT(*)`. Useful for large PostgreSQL tables where `COUNT(*)` requires a full table scan.
+
 <Note>
 **Validation ranges:**
 - **Page Size**: 10 -- 100,000 rows (values outside this range are clamped)