Heidi becomes unresponsive when running LIKE "%XY%" queries on large text fields

Is there a setting that prevents Heidi from becoming unresponsive when running queries that return large result sets? The results are displayed, but the query editor becomes unresponsive. A bug report window opens in a separate tab, but closing it does not resolve the issue. I always have to restart the application. Using LIMIT does not help in this case.

No there is no setting for preventing that. HeidiSQL has its issues with large contents in result grids. You can prefer the Data tab if you are mostly querying simple tables. The Data tab grid loads the first 256 chars of large (text) fields. Once you start to edit, delete or copy something, HeidiSQL loads the full data of selected rows. Lazy loading if you want to name it.

In my opinion it is a access violation bug. It even gives me a bug report:

date/time : 2026-06-30, 10:44:29, 815ms computer name : [REDACTED] wts client name : [REDACTED] user name : [REDACTED] registered owner : [REDACTED] operating system : Windows 2019 x64 build 20348 system language : German system up time : 6 days program up time : 1 minute 58 seconds processors : 8x Intel(R) Xeon(R) Gold 6136 CPU @ 3.00GHz physical memory : 24254/32767 MB (free/total) free disk space : (C:) 46,36 GB display mode : 2012x1171, 32 bit process id : $4294 allocated memory : 118,33 MB largest free block : 131023,10 GB executable : heidisql.exe exec. date/time : 2026-06-22 17:06 version : 12.20.0.7320 compiled with : Delphi 12 madExcept version : 5.1.5 callstack crc : $ec4fc685, $cdc795a8, $cdc795a8 exception number : 1 exception class : EAccessViolation exception message : Access violation at address 0000000000EDD7C4 in module 'heidisql.exe' (offset 50D7C4). Read of address 0000000000000638.

main thread ($2ff4): 00edd7c4 heidisql.exe SynEdit 11583 +1 TCustomSynEdit.GetWordWrap 00edd7f6 heidisql.exe SynEdit 11592 +1 TCustomSynEdit.SetWordWrap 0180d822 heidisql.exe Main 6407 +24 TMainForm.PageControlMainChange 00d30071 heidisql.exe Vcl.ComCtrls TCustomTabControl.Change 00d325a8 heidisql.exe Vcl.ComCtrls TPageControl.Change 00d310b5 heidisql.exe Vcl.ComCtrls TCustomTabControl.CNNotify 009df6f1 heidisql.exe System TObject.Dispatch 00c9f107 heidisql.exe Vcl.Controls TControl.WndProc 00ca6e1b heidisql.exe Vcl.Controls TWinControl.WndProc 00c9ec0f heidisql.exe Vcl.Controls TControl.Perform 00ca7049 heidisql.exe Vcl.Controls DoControlMsg 00ca8246 heidisql.exe Vcl.Controls TWinControl.WMNotify 009df6f1 heidisql.exe System TObject.Dispatch 00c9f107 heidisql.exe Vcl.Controls TControl.WndProc 00ca6e1b heidisql.exe Vcl.Controls TWinControl.WndProc 00ca5eea heidisql.exe Vcl.Controls TWinControl.MainWndProc 00bb2a83 heidisql.exe System.Classes StdWndProc 7ffc0deb USER32.dll SendMessageW 7ffbe282 COMCTL32.dll #342 7ffc0deb USER32.dll CallWindowProcW 00ca6fe7 heidisql.exe Vcl.Controls TWinControl.DefaultHandler 00c9f9c1 heidisql.exe Vcl.Controls TControl.WMLButtonDown 00d336b6 heidisql.exe Vcl.ComCtrls TPageControl.WMLButtonDown 009df6f1 heidisql.exe System TObject.Dispatch 00c9f107 heidisql.exe Vcl.Controls TControl.WndProc 00ca6e1b heidisql.exe Vcl.Controls TWinControl.WndProc 00ca5eea heidisql.exe Vcl.Controls TWinControl.MainWndProc 00bb2a83 heidisql.exe System.Classes StdWndProc 7ffc0deb USER32.dll DispatchMessageW 00e4ed60 heidisql.exe Vcl.Forms TApplication.ProcessMessage 00e4edd3 heidisql.exe Vcl.Forms TApplication.HandleMessage 00e4f22a heidisql.exe Vcl.Forms TApplication.Run 018511d5 heidisql.exe heidisql 120 +45 initialization 7ffc0d2d KERNEL32.DLL BaseThreadInitThunk 7ffc0ea5 ntdll.dll RtlUserThreadStart

Another clarification.

The bug only occurs when I have "Text lines in data grid" on 1. When I switch to 2 or more it works but just becomes slow. Maybe something you could look into it?

Best regards

Here's the screenshot "Textzeilen im Datengrid"

Yes that lines setting is known to prevent some of the crashes, but not reliably. The cause lies in a very large number of WM_PAINT Windows messages sent and received. I could yet not find a way for reducing them to a normal amount.