From e791339e86f8a42802a279c23c3884d26644b3c8 Mon Sep 17 00:00:00 2001
From: Ansgar Becker <ansgarbecker@users.noreply.github.com>
Date: Tue, 27 Jan 2009 19:32:20 +0000
Subject: [PATCH] Try a pragmatic workaround for bug #761 (Large tables crash
 TVirtualTree) and bug #950 (Decrease memory usage for grid results). Makes
 the data grid hard limited to a maximum of 100,000 rows/nodes (means ~6M
 memory consumption just for the tree nodes). It seems reasonable to do this
 as on large tables you normally create a filter to find specific rows rather
 than scrolling and looking the rows up by hand. The grid is now able again to
 display superlarge tables without losing too much memory for data of few
 interest. However, I hope there's no complaint the other way around for why
 we don't display all rows instead.

---
 components/heidisql/include/const.inc |  3 +++
 source/main.pas                       | 24 ++++++++++++++----------
 2 files changed, 17 insertions(+), 10 deletions(-)

diff --git a/components/heidisql/include/const.inc b/components/heidisql/include/const.inc
index b13795f1..9a61bf73 100644
--- a/components/heidisql/include/const.inc
+++ b/components/heidisql/include/const.inc
@@ -292,6 +292,9 @@ const
   // Data grid: How many rows to fetch at a time.
   GRIDMAXROWS: Cardinal = 500;
 
+  // Data grid: How many rows to display in total
+  GRIDMAXTOTALROWS = 100000;
+
   // How many milliseconds to wait before showing a 'waiting for database' sign.
   QUERYWAITTIME: Integer = 2500;
 
diff --git a/source/main.pas b/source/main.pas
index b37205d7..4845fcb0 100644
--- a/source/main.pas
+++ b/source/main.pas
@@ -762,7 +762,7 @@ type
     function GetActiveData: PGridResult;
     procedure WaitForQueryCompletion(WaitForm: TfrmQueryProgress; query: TMySqlQuery; ForceDialog: Boolean);
     function RunThreadedQuery(AQuery: WideString; ForceDialog: Boolean): TMysqlQuery;
-    procedure DisplayRowCountStats;
+    procedure DisplayRowCountStats(MatchingRows: Int64);
     procedure insertFunction(Sender: TObject);
     function GetActiveDatabase: WideString;
     function GetSelectedTable: WideString;
@@ -3426,6 +3426,7 @@ var
   rx                   : TRegExpr;
   ColType              : String;
   ColExists, ShowIt    : Boolean;
+  MatchingRows         : Int64;
 
 procedure InitColumn(name: WideString; ColType: String; Visible: Boolean);
 var
@@ -3645,7 +3646,10 @@ begin
         sl_query.Add(select_from);
         // Apply custom WHERE filter
         if DataGridCurrentFilter <> '' then sl_query.Add('WHERE ' + DataGridCurrentFilter);
-        count := StrToInt(GetVar(sl_query.Text));
+        MatchingRows := StrToInt(GetVar(sl_query.Text));
+        count := MatchingRows;
+        if count > GRIDMAXTOTALROWS then
+          count := GRIDMAXTOTALROWS;
       except
         on E:Exception do begin
           // Most likely we have a wrong filter-clause when this happens
@@ -3681,7 +3685,7 @@ begin
         DataGrid.OffsetXY := Point(0, 0); // Scroll to top left
         FreeAndNil(PrevTableColWidths); // Throw away remembered, manually resized column widths
       end;
-      DisplayRowCountStats;
+      DisplayRowCountStats(MatchingRows);
       dataselected := true;
 
       pcChange(self);
@@ -3704,9 +3708,8 @@ end;
   Calculate + display total rowcount and found rows matching to filter
   in data-tab
 }
-procedure TMainForm.DisplayRowCountStats;
+procedure TMainForm.DisplayRowCountStats(MatchingRows: Int64);
 var
-  rows_matching    : Int64; // rows matching to where-filter
   rows_total       : Int64; // total rowcount
   IsFiltered, IsInnodb: Boolean;
   ds: TDataSet;
@@ -3740,13 +3743,14 @@ begin
     lblDataTop.Caption := lblDataTop.Caption + ' [View]';
   end;
 
-  rows_matching := DataGrid.RootNodeCount;
+  if( MatchingRows <> rows_total ) and IsFiltered then
+    lblDataTop.Caption := lblDataTop.Caption + ', ' + FormatNumber(MatchingRows) + ' matching to filter';
 
-  if( rows_matching <> rows_total ) and IsFiltered then
-    lblDataTop.Caption := lblDataTop.Caption + ', ' + FormatNumber(rows_matching) + ' matching to filter';
-
-  if ( rows_matching >= rows_total ) and IsFiltered then
+  if ( MatchingRows >= rows_total ) and IsFiltered then
     lblDataTop.Caption := lblDataTop.Caption + ', filter matches all rows';
+
+  if MatchingRows > DataGrid.RootNodeCount then
+    lblDataTop.Caption := lblDataTop.Caption + ', limited to '+FormatNumber(DataGrid.RootNodeCount);
 end;