Autolimit optimizations:

- Do not uncheck the LIMIT checkbox if the value in EditLimitEnd is larger than the total row count. In such (very common) cases it doesn't matter if a LIMIT is applied or not, so we don't annoy the user now by not auto-unchecking it.
- EditLimitEnd's value was never increased, only decreased, as of r1521. This seems more annoying than it helps prioritizing what the user wants.

source/childwin.pas

@@ -396,7 +396,7 @@ type
     function ExecuteQuery(query: String): TDataSet;
     function CreateOrGetRemoteQueryTab(sender: THandle): THandle;
     procedure menuDeleteSnippetClick(Sender: TObject);
-    function GetCalculatedLimit( Table: String ): Int64;
+    procedure GetCalculatedLimit(Table: String; out Limit, AllRows: Int64);
     procedure menuExploreClick(Sender: TObject);
     procedure menuInsertSnippetAtCursorClick(Sender: TObject);
     procedure menuLoadSnippetClick(Sender: TObject);
@@ -1175,9 +1175,7 @@ var
   PrimaryKeyColumns    : TStringList;
   reg_value            : String;
   select_base          : String;
-  limit,
-  tmpLimitStart,
-  tmpLimitEnd          : Int64;
+  limit, allrows       : Int64;
   ds                   : TDataSet;
   sl_query             : TStringList;
   DisplayedColumnsList : TStringList;
@@ -1191,17 +1189,15 @@ begin
     // and the user did not explicitely set the limits and pressed OK in mainform
     if (Sender <> Mainform.ButtonOK) and (not dataselected) then begin
       // limit number of rows fetched if more than ~ 5 MB of data
-      limit := GetCalculatedLimit( SelectedTable );
+      GetCalculatedLimit( SelectedTable, limit, allrows );
 
-      // adjust limit in GUI
-      if limit <= 0 then
-        mainform.CheckBoxLimit.Checked := false
-      else begin
+      // adjust limit in GUI:
+      // Uncheck checkbox if calculated limit is larger than wanted rowcount
+      if (limit <= 0) and (AllRows > MakeInt(mainform.EditLimitEnd.Text)) then
+        mainform.CheckBoxLimit.Checked := false;
+      if limit > 0 then begin
         mainform.CheckBoxLimit.Checked := true;
-        tmpLimitStart := MakeInt(mainform.EditLimitStart.Text);
-        tmpLimitEnd := MakeInt(mainform.EditLimitEnd.Text);
-        if tmpLimitEnd > limit then
-          mainform.EditLimitEnd.Text := IntToStr(limit);
+        mainform.EditLimitEnd.Text := IntToStr(limit);
       end;
       mainform.Repaint;
     end;
@@ -4183,9 +4179,9 @@ end;
   Detect average row size and limit the number of rows fetched at
   once if more than ~ 5 MB of data
 }
-function TMDIChild.GetCalculatedLimit( Table: String ): Int64;
+procedure TMDIChild.GetCalculatedLimit(Table: String; out Limit, AllRows: Int64);
 var
-  AvgRowSize, RecordCount : Int64;
+  AvgRowSize : Int64;
   ds: TDataSet;
 const
   // how much overhead this application has per row
@@ -4193,27 +4189,27 @@ const
   // average row size guess for mysql server < 5.0
   ROW_SIZE_GUESS: Integer = 2048;
 begin
-  result := -1;
+  Limit := -1;
   try
     ds := GetResults('SHOW TABLE STATUS LIKE ' + esc(Table));
     if ds = nil then exit;
     if ds.FieldByName('Avg_row_length').IsNull or ds.FieldByName('Rows').IsNull then begin
       // Guessing row size and count for views, fixes bug #346
       AvgRowSize := ROW_SIZE_GUESS + ROW_SIZE_OVERHEAD;
-      RecordCount := MaxInt;
+      AllRows := MaxInt;
     end else begin
       AvgRowSize := MakeInt( ds.FieldByName( 'Avg_row_length' ).AsString ) + ROW_SIZE_OVERHEAD;
-      RecordCount := MakeInt( ds.FieldByName( 'Rows' ).AsString );
+      AllRows := MakeInt( ds.FieldByName( 'Rows' ).AsString );
     end;
-    if AvgRowSize * RecordCount > prefLoadSize then
+    if AvgRowSize * AllRows > prefLoadSize then
     begin
-      result := Trunc( prefLoadSize / AvgRowSize );
-      if result >= RecordCount then result := -1;
+      Limit := Trunc( prefLoadSize / AvgRowSize );
+      if Limit >= AllRows then Limit := -1;
     end;
     ds.Close;
     FreeAndNil(ds);
   finally
-    debug( 'GetCalculatedLimit: ' + formatnumber(result) );
+    debug( 'GetCalculatedLimit: ' + formatnumber(Limit) );
   end;
 end;
 

source/exportsql.pas

@@ -495,7 +495,7 @@ var
   extended_insert           : Boolean;
   max_allowed_packet        : Int64;
   thesevalues               : String;
-  valuescount, limit        : Integer;
+  valuescount               : Integer;
   donext                    : Boolean;
   PBuffer                   : PChar;
   sql, current_characterset : String;
@@ -504,7 +504,7 @@ var
   target_cliwa              : Boolean;
   ansi                      : Boolean;
   RecordCount_all, RecordCount_one, RecordNo_all,
-  offset                    : Int64;
+  offset, limit             : Int64;
   sql_select                : String;
   cwin                      : TMDIChild;
   query                     : TDataSet;
@@ -976,8 +976,7 @@ begin
           once if more than ~ 5 MB of data
           Be sure to do this step before the table is locked!
         }
-        RecordCount_all := MakeInt( cwin.GetVar( 'SELECT COUNT(*) FROM ' + sourceMask(checkListTables.Items[i]) ) );
-        limit := cwin.GetCalculatedLimit( checkListTables.Items[i] );
+        cwin.GetCalculatedLimit( checkListTables.Items[i], limit, RecordCount_all);
 
         if RecordCount_all = 0 then begin
           if tofile then