In my pre-Ext era I'd been developing a PHP web application that dealt with quite large databases with record count per table 10000+. The number of records is no problem for database backends, they can usually handle millions of records easily.
The big tables are problem first for (web) developer as he cannot, let's say, generate a combo with 1000 options. Yes, he can, but what about generation time and network throughput? Second, big tables are problem for users in that that user wants quick answers to questions like: "Show me overdue invoices." and he doesn't want to go through thousands of records to find them.
Keeping this in mind I have developed the grid filtering that I consider ideal for such purposes; my users praise it highly too. Let me describe it.
Each grid has input fields just beneath the column labels where user can type the filter expression. The database backend (mySQL in my case) uses rlike function to filter so if user learns the syntax he can put really advanced expressions there. Expressions in individual inputs are connected by and operator in SQL where clause. See attachment 1. You can see also "Clear filter" and "Apply filter" on the right of the picture.
If we take the invoice list as an example and we want to answer the above question we put ">0" in the "Owed sum" field and "< now()" in the "Due date" field, then click "Apply filter" and we get the list. If "Show totals" is checked we get also "Total owed sum".
I first implemented this logic but life has shown that users usually have "Sets of question" they want answers to asked over and over. Letting users to have lists of such filters (maybe written on a paper) and let them to write these to the fields over and over had led to complaints and frustrations.
Thus, I've developed the filter management system that allows to give a name to the filter once setup and to save it with the given name. In out example we would give filter name "Overdue Invoices" and we'd save it. Whenever we need the list we just click "Saved filters" icon on the left, click an item from the presented list and we have the answer. See attachments 2 and 3.
The last convenience feature is that if we have relatively short list of possibilities we put the list in the (inline) popup so user can choose. In this example it is possibility to choose the "Seller". See attachment 4.
Maybe this is not something new under the sun, moon and stars but it's concept that works for years with full user's satisfaction.
I'd like to have it in Ext. And you?