As an update I have noticed the :filter-expr that could help me with querying/filtering the data.

I am wondering if it's possible to reuse the :sh output in further queries (eg: loading data parsed by a script from "unrelated" file into SQL data table)?

but the output table format is truncated for log messages and therefore not very useful for interactive use.

Are you speaking of how column widths are limited and a long value will have an ellipsis is inserted in the middle when it's truncated? To see the full value you can press p to open the details overlay. The full content should be in there and you can copy a column by focusing on the overlay (press CTRL+]), moving the selection to the column, and then pressing c to copy to the clipboard.

In this picture, the log_body column is long and has multiple lines:

Then I'm finding most of the log format features lacking for extracting data for known message patterns:

I would use search tables for the example messages you gave.

• tagging patterns as identifiers

I'm not sure what you mean by this.

• normalizing values replace machine-readable values with human-readable versions pulled from other log lines and/or external metadata

A recent addition I made was to add an annotation to postgres error logs with a pointer to the location of the syntax error (see this issue)

• adding fields for known patterns
  • I would absolutely love to put [a-zA-Z0-9+/=]{44} pattern (that can appear more than once in a line) into a peers field containing a list of peers for the log line, each of those working as identifier with a separate color

I'd like to help, but it's kinda hard without some real log files to reference. It's possible we could write some scripts that do the things you want. And, I would like to make sure lnav is fleshed out enough to work with real-world scenarios.

Is there a way to turn a result of SQL query into a browsable LOG view or otherwise modify it?

As you mentioned, :filter-expr get's close to that. Otherwise, you can generate a report by writing a script that runs SQL and lnav commands. lnav's Markdown support has grown over time, so you can it's getting easier to make nicer looking stuff.

Thanks for looking into it after such a long time. I can ask whether I could make the code available somewhere (it's for work), but what I ended up doing is roughly:

• created a pre-processing the log file to JSON with a Go program
  • it can parse the other files in the "debug bundle" to augment log lines with whatever I might need
• created a custom JSON format:
  • coloring-coding some relevant patterns
  • marking start/end of the sections
  • reorders log line pieces with line-format
    • there are 2 traifing fields raw_line and filterable that have .value.*.hidden: true equivalents
      • those allow me to search for my custom "tags" without cluttering the view

The final result is extremely useful, but I expected to be able to do those things efficiently within lnav itself before I got started with it. This is by no means a "bad review", but I was unable to determine whether I could do the things I did with just lnav at all.

lnav could really use some real-world elaborate setups for logs processing/enhancing