Frequently Asked Questions

The type detection resolves incorrect column type for my data.

The QueryCat prefetches first 10 rows to understand what columns data has and what type. However, it might be wrong in some cases. For example:

OrderId,Comment
0000512,"I'll hack the auxiliary SMS card, that should card the SMS card!"
1000451,"If we synthesize the pixel, we can get to the HDD pixel through the multi-byte HDD pixel!"
...
T000004,"I'll back up the back-end COM panel, that should panel the COM panel!"

According to the first rows we can consider the OrderId column has integer type. However, it might contain letters. So following query will produce error:

select * from 'orders.csv';

To force QueryCat override column type apply cast operator to that column:

select OrderId::string, Comment from 'orders.csv';

The fatal error occurs on application start

It is possible that plugins are out of date and/or they do not conform the latest backend plugin API. So it is better try:

  1. Update QueryCat application to the latest version. You can find it here: https://github.com/krasninja/querycat/releases/.
  2. Update all plugins to the latest version. Command is qcat plugin update "*".
  3. If error still there post new issue with the steps to reproduce and full stack trace here: https://github.com/krasninja/querycat/issues/new.

The query performance is poor

The QueryCat is not a true database engine. It doesn't know anything about input sources and there is no information about total rows, indexes, statistics, etc. So query planner is simple and straightforward. You can try the following tips to improve query performance:

  1. Reorder join statements. Try to move most slow input sources to the right.
  2. Save slow input sources into files first.
  3. Create the GitHub issue with the detailed information. It might be an application bug.

Does it send any local or personal information?

The QueryCat does not send any local or personal information to the author or any company.

Why do I need to install "proxy" to run plugins?

The plugins are written in .NET and require the full version of .NET platform to run them. Since QueryCat is compiled with AOT it does not have it. That's why we need another "proxy" to load plugin assemblies.