<p dir="auto">Make sure these boxes are checked before submitting your issue - thank you!</p>
<ul class="contains-task-list">
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox" checked=""> I have checked the superset logs for python stacktraces and included it here as text if any</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox" checked=""> I have reproduced the issue with at least the latest released version of superset</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox" checked=""> I have checked the issue tracker for the same issue and I haven't found one similar</li>
</ul>
<h3 dir="auto">Superset version</h3>
<p dir="auto">Superset 0.19.1</p>
<h3 dir="auto">Expected results</h3>
<p dir="auto">A normal  Time Series - Line Chart.<br>
Like this<br>
<a target="_blank" rel="noopener noreferrer nofollow" href="https://camo.githubusercontent.com/35057951b148fe15434330b09f7ffea7f3468de21e1c199022acc758fa75a929/68747470733a2f2f7773342e73696e61696d672e636e2f6c617267652f303036744e633739677931666a6335316c6a7977616a33316b77306f353764612e6a7067"><img src="https://camo.githubusercontent.com/35057951b148fe15434330b09f7ffea7f3468de21e1c199022acc758fa75a929/68747470733a2f2f7773342e73696e61696d672e636e2f6c617267652f303036744e633739677931666a6335316c6a7977616a33316b77306f353764612e6a7067" alt="" data-canonical-src="https://ws4.sinaimg.cn/large/006tNc79gy1fjc51ljywaj31kw0o57da.jpg" style="max-width: 100%;"></a></p>
<h3 dir="auto">Actual results</h3>
<p dir="auto"><a target="_blank" rel="noopener noreferrer nofollow" href="https://camo.githubusercontent.com/dc97b01b3b5d8bc4d0638877127646179cfec8b2a815d60a50d732cacacefb81/68747470733a2f2f7773322e73696e61696d672e636e2f6c617267652f303036744e633739677931666a6335326c39326b656a33316b77306d6e3432322e6a7067"><img src="https://camo.githubusercontent.com/dc97b01b3b5d8bc4d0638877127646179cfec8b2a815d60a50d732cacacefb81/68747470733a2f2f7773322e73696e61696d672e636e2f6c617267652f303036744e633739677931666a6335326c39326b656a33316b77306d6e3432322e6a7067" alt="" data-canonical-src="https://ws2.sinaimg.cn/large/006tNc79gy1fjc52l92kej31kw0mn422.jpg" style="max-width: 100%;"></a></p>
<h3 dir="auto">Steps to reproduce</h3>
<ol dir="auto">
<li>I have a dimension have 'NULL'. What I mean is not all row have value.</li>
<li>Use this dimension as Group By.</li>
<li>Query.</li>
</ol>
<h3 dir="auto">More</h3>
<p dir="auto">I add a Filters into this form. The Filters is same dimension is 'event_name', relation is '!=', <strong>but the value I did not input anything.</strong></p>
<p dir="auto">Then, I can see the expected results.</p>
<p dir="auto">I guess the reason is that default fill 0 into NULL, but my dimension is TEXT. Then occur <code class="notranslate">unorderable types: str() &gt; int()</code>.</p>
<p dir="auto">And this is similar issue.<br>
<a href="https://github.com/apache/incubator-superset/issues/3029" data-hovercard-type="issue" data-hovercard-url="/apache/superset/issues/3029/hovercard">#3029</a></p>
<p dir="auto">Make sure these boxes are checked before submitting your issue - thank you!</p>
<ul class="contains-task-list">
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox"> I have checked the superset logs for python stacktraces and included it here as text if any</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox"> I have reproduced the issue with at least the latest released version of superset</li>
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox"> I have checked the issue tracker for the same issue and I haven't found one similar</li>
</ul>
<h3 dir="auto">Superset version</h3>
<h3 dir="auto"></h3>
<p dir="auto">I  installed the superset on one server(redhat os ) and connecting to redshift to perform a query.<br>
I superseded that superset server might be slow when several users connect and use ...<br>
Is there a way to install superset on multiple servers and load balancing when users connect?</p>