QTableView performances

[wysota]

I really suggest to modify the implementation of data(). It is currently very inefficient and it's one of the most often called methods.

[miraks]

I really suggest to modify the implementation of data(). It is currently very inefficient and it's one of the most often called methods.

I will try but it's not so easy !
I will take you informed.

In any case, thank you for your help.

[miraks]

Hi wysota,

I have got 2 bad news:

1-I optimized data method and after that, I commented in data methods all the code concerning decoration, tooltip, alignment, etc to keep only the text. Even with this, I win only 6% of performances. .
Conclusion: even with perfect code in data, I won't have good performances.

2-The solution based on layoutAboutToBeChanged + layoutChanged generates some regressions.
(indexes seems to be not recomputed and so are still pointing on deleted internal data).

I don't know what to do.

PS1: I attached my new implementation.
PS2: I don't know if it's very important, but I use a proxy (filter & sort) too.

[wysota]

The implementation is still very inefficient. You are still comparing strings instead of enums or numbers and you don't do any serious caching of calculated data.

6% performance gain is already much, don't underestimate it.

[miraks]

Hi wysota,

Today, I have got a good new.
I understood why I have so bad performances.
In fact, it's due to these lines:

ui.kOperationView->verticalHeader()->setResizeMode(QHeaderView::ResizeToContents);
ui.kOperationView->horizontalHeader()->setResizeMode(QHeaderView::ResizeToContents);

ui.kOperationView->verticalHeader()->setResizeMode(QHeaderView::ResizeToContents);
ui.kOperationView->horizontalHeader()->setResizeMode(QHeaderView::ResizeToContents);

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If I comment these lines, I have got:

##methode                                               , nb call , millisecondes , moyenne   , min        , max     , propre   , moyenne propre
##SKGServices::executeSelectSqliteOrder(QSqlDatabase)   , 173     , 2250.3        , 13.0075    , 0.0319843  , 757.705 , 2250.3  , 13.0075
##SKGObjectModelBase::data                              , 77777   , 2022.72       , 0.0260067  , 0.00187886 , 17.3499 , 2011.33 , 0.0258602
##SKGObjectModelBase::refresh-reset                     , 13      , 4078.05       , 313.696    , 0.00701368 , 3962.67 , 1081.16 , 83.166
##SKGObjectModel::data                                  , 71620   , 2738.77       , 0.0382403  , 0.00292969 , 17.3791 , 776.344 , 0.0108398
##SKGServices::executeSqliteOrder(QSqlDatabase)         , 379     , 1319.9        , 3.48257    , 0.0279003  , 444.459 , 679.188 , 1.79205
##SKGMainPanel::SKGMainPanel                            , 1       , 2419.67       , 2419.67    , 2419.67    , 2419.67 , 372.141 , 372.141
##SKGObjectModelBase::index                             , 73266   , 295.21        , 0.00402929 , 0.00190628 , 10.6721 , 295.21  , 0.00402929
##SKGObjectModelBase::rowCount                          , 73305   , 223.636       , 0.00305076 , 0.00187886 , 11.12   , 223.636 , 0.00305076
##SKGObjectModelBase::clear                             , 17      , 201.88        , 11.8753    , 0.00792778 , 176.784 , 201.88  , 11.8753
##SKGObjectBase::getObjects                             , 62      , 1078.61       , 17.3969    , 0.0670469  , 932.943 , 184.245 , 2.9717
##SKGObjectModelBase::headerData                        , 9244    , 137.556       , 0.0148806  , 0.00188088 , 1.31897 , 104.604 , 0.0113158
##SKGSortFilterProxyModel::filterAcceptsRow             , 4022    , 336.626       , 0.0836961  , 0.023957  , 0.784051 , 90.5983 , 0.0225257

##methode                                               , nb call , millisecondes , moyenne   , min        , max     , propre   , moyenne propre
##SKGServices::executeSelectSqliteOrder(QSqlDatabase)   , 173     , 2250.3        , 13.0075    , 0.0319843  , 757.705 , 2250.3  , 13.0075
##SKGObjectModelBase::data                              , 77777   , 2022.72       , 0.0260067  , 0.00187886 , 17.3499 , 2011.33 , 0.0258602
##SKGObjectModelBase::refresh-reset                     , 13      , 4078.05       , 313.696    , 0.00701368 , 3962.67 , 1081.16 , 83.166
##SKGObjectModel::data                                  , 71620   , 2738.77       , 0.0382403  , 0.00292969 , 17.3791 , 776.344 , 0.0108398
##SKGServices::executeSqliteOrder(QSqlDatabase)         , 379     , 1319.9        , 3.48257    , 0.0279003  , 444.459 , 679.188 , 1.79205
##SKGMainPanel::SKGMainPanel                            , 1       , 2419.67       , 2419.67    , 2419.67    , 2419.67 , 372.141 , 372.141
##SKGObjectModelBase::index                             , 73266   , 295.21        , 0.00402929 , 0.00190628 , 10.6721 , 295.21  , 0.00402929
##SKGObjectModelBase::rowCount                          , 73305   , 223.636       , 0.00305076 , 0.00187886 , 11.12   , 223.636 , 0.00305076
##SKGObjectModelBase::clear                             , 17      , 201.88        , 11.8753    , 0.00792778 , 176.784 , 201.88  , 11.8753
##SKGObjectBase::getObjects                             , 62      , 1078.61       , 17.3969    , 0.0670469  , 932.943 , 184.245 , 2.9717
##SKGObjectModelBase::headerData                        , 9244    , 137.556       , 0.0148806  , 0.00188088 , 1.31897 , 104.604 , 0.0113158
##SKGSortFilterProxyModel::filterAcceptsRow             , 4022    , 336.626       , 0.0836961  , 0.023957  , 0.784051 , 90.5983 , 0.0225257

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As you can see, the number of calls is drastically reduced and performances are better (before 43s into data method, now 2s into data method ==> it's better than 6% ).

Is it normal to have so bad performances when ResizeToContents is used ?

[wysota]

Yes, that's normal. sizeHint is queried all the time which in turns calls data() all the time, etc. I thought you knew that so I didn't even bother to mention it, sorry

But honestly it's because of your hand-crafted profiler - it doesn't monitor methods which are called automatically by Qt or that are implemented by Qt, hence no references to sizeHint reading and hence my impression you weren't resizing columns to contents.