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    <p>The reason why <code>AddChild()</code> is not encouraged is that it breaks the virtual paradigm of the component - you create all the nodes, even though you may never need them. Say the query returns 100 records but the tree shows 10 nodes at the time. Now if the user nevers scrolls down you have wasted resources for 90 nodes as they are never needed (don't became visible). So if you're worried about memory usage, <code>AddChild()</code> is bad idea. Another thing is that if the resultset is big, populating the tree takes time and your app isn't responsive at that time. When using virtual way (<code>RootNodeCount</code> and <code>OnInitNode</code>) the tree is "ready" immediately and user doesn't experience any delay.</p> <p>Then again, in case of (relatively) small resultsets using <code>AddChild()</code> might be the best option - it would allow you to load data in one short transaction. Ie in case of tree structure it would make sense to load whole "level" at once when user expands the parent node.</p> <p>Using DB with VT is a bit tricky as the DB query is special resource too, with it's own constraints (you want to keep transactions short, it is relatively slow, the DB might only support one way cursor etc). <br> So I'd say it is something you have to decide on each individual case, depending on the use case and amount of data, ie</p> <ul> <li>small resultset is OK to load all at once with <code>AddChild()</code> or into internal data structure and then using it throught VT's events;</li> <li>loading one level at time is probably good compromise for trees;</li> <li>in case of very large resultsets loading in batches might give good perfomance and memory usage compromise but adds complexity to the code managing VT.</li> </ul>
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    1. POVirtualStringTree Correct/recommended use
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    1. CO+1 thanks for the answer. It seems most of my trees should be fine since they only load <100 nodes from the DB and i would prefer to have lesser larger queries rather than more smaller ones. There are a couple of places where the query resultset is larger however. Maybe i will consider changing in these circumstances.
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    2. COjust tried using rootnodecount and a TQuery. Not as simple as i would have thought since TQuery does not provide random access to records like an array does. So it looks like i will stick with what ive got for now
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    3. COI have a custom TQuery like control I wrote that queries DB and keeps record set in memory. I tried using OnInit and I can not seem to make it work. In tracing calls to OnInit and GetText, I noticed OnInit is called 2x then GetText. In my OnInit, my TQuery like control supports ->Next(); so upon each call to OnInit, I populate the VST Data * with data and call the ->Next(). I wind up with a tree of repeated information. Is there any working C++ examples you can point too? The documenation talks about OnInit to resize cells and most stuff is in obj-Pascal.
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