From c2594e40c0b426b559a575248a07884913a35387 Mon Sep 17 00:00:00 2001
From: Ansgar Becker <anse@heidisql.com>
Date: Thu, 21 Dec 2017 15:25:03 +0100
Subject: [PATCH] Find out whether the previously selected database has some
 locked tables, and if so, don't select it at startup time. Closes #49

---
 source/dbconnection.pas | 28 +++++++++++++++++++++++++++-
 source/main.pas         |  5 ++++-
 2 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/source/dbconnection.pas b/source/dbconnection.pas
index 8c69ffdfd..ce04c4578 100644
--- a/source/dbconnection.pas
+++ b/source/dbconnection.pas
@@ -286,7 +286,8 @@   TConnectionParameters = class(TObject)
     spSessionVariables, spGlobalVariables,
     spISTableSchemaCol,
     spUSEQuery, spKillQuery, spKillProcess,
-    spFuncLength, spFuncCeil);
+    spFuncLength, spFuncCeil,
+    spLockedTables);
 
   TDBConnection = class(TComponent)
     private
@@ -435,6 +436,7 @@   TDBConnection = class(TComponent)
       property LockedByThread: TThread read FLockedByThread write SetLockedByThread;
       property Datatypes: TDBDataTypeArray read FDatatypes;
       property Favorites: TStringList read FFavorites;
+      function GetLockedTableCount(db: String): Integer;
     published
       property Active: Boolean read FActive write SetActive default False;
       property Database: String read FDatabase write SetDatabase;
@@ -2034,6 +2036,7 @@ procedure TDBConnection.DoBeforeConnect;
       FSQLSpecifities[spKillProcess] := 'KILL %d';
       FSQLSpecifities[spFuncLength] := 'LENGTH';
       FSQLSpecifities[spFuncCeil] := 'CEIL';
+      FSQLSpecifities[spLockedTables] := '';
     end;
     ngMSSQL: begin
       FSQLSpecifities[spEmptyTable] := 'DELETE FROM ';
@@ -2050,6 +2053,7 @@ procedure TDBConnection.DoBeforeConnect;
       FSQLSpecifities[spKillProcess] := 'KILL %d';
       FSQLSpecifities[spFuncLength] := 'LEN';
       FSQLSpecifities[spFuncCeil] := 'CEILING';
+      FSQLSpecifities[spLockedTables] := '';
     end;
     ngPgSQL: begin
       FSQLSpecifities[spEmptyTable] := 'DELETE FROM ';
@@ -2066,6 +2070,7 @@ procedure TDBConnection.DoBeforeConnect;
       FSQLSpecifities[spKillProcess] := 'SELECT pg_cancel_backend(%d)';
       FSQLSpecifities[spFuncLength] := 'LENGTH';
       FSQLSpecifities[spFuncCeil] := 'CEIL';
+      FSQLSpecifities[spLockedTables] := '';
     end;
 
   end;
@@ -2225,6 +2230,9 @@ procedure TMySQLConnection.DoAfterConnect;
 
   if ServerVersionInt >= 50000 then
     FSQLSpecifities[spKillQuery] := 'KILL QUERY %d';
+
+  if ServerVersionInt >= 50124 then
+    FSQLSpecifities[spLockedTables] := 'SHOW OPEN TABLES FROM %s WHERE in_use!=0';
 end;
 
 
@@ -3997,6 +4005,24 @@ function TPGConnection.MaxAllowedPacket: Int64;
 end;
 
 
+function TDBConnection.GetLockedTableCount(db: String): Integer;
+var
+  sql: String;
+  LockedTables: TStringList;
+begin
+  // Find tables which are currently locked.
+  // Used to prevent waiting time in GetDBObjects.
+  sql := GetSQLSpecifity(spLockedTables);
+  if sql.IsEmpty then begin
+    Result := 0;
+  end else begin
+    LockedTables := GetCol(Format(sql, [QuoteIdent(db,False)]));
+    Result := LockedTables.Count;
+    LockedTables.Free;
+  end;
+end;
+
+
 function TMySQLConnection.GetRowCount(Obj: TDBObject): Int64;
 var
   Rows: String;
diff --git a/source/main.pas b/source/main.pas
index 72a039e77..86384435f 100644
--- a/source/main.pas
+++ b/source/main.pas
@@ -3693,7 +3693,10 @@ function TMainform.InitConnection(Params: TConnectionParameters; ActivateMe: Boo
       RestoreLastActiveDatabase := AppSettings.ReadBool(asRestoreLastUsedDB);
       AppSettings.SessionPath := Params.SessionPath;
       LastActiveDatabase := AppSettings.ReadString(asLastUsedDB);
-      if RestoreLastActiveDatabase and (Connection.AllDatabases.IndexOf(LastActiveDatabase) >- 1) then begin
+      if RestoreLastActiveDatabase
+        and (Connection.AllDatabases.IndexOf(LastActiveDatabase) >- 1)
+        and (Connection.GetLockedTableCount(LastActiveDatabase) = 0)
+        then begin
         SetActiveDatabase(LastActiveDatabase, Connection);
         DBNode := FindDBNode(DBtree, Connection, LastActiveDatabase);
         if Assigned(DBNode) then