Perforce Repository and Incoming tabs empty: Request too large, see 'p4 help maxresults'

Problem

In a JetBrains IDE with the Perforce plugin, clicking Refresh in the Repository or Incoming tab of the Version Control tool window fails after a delay, and the tab stays empty. The IDE shows one of these server errors:

Request too large (over 1000000); see 'p4 help maxresults'.
Too many rows scanned (over 6000000); see 'p4 help maxscanrows'.

The limit in the message is the server's MaxResults or MaxScanRows value. The problem appears on large depots with a long integration (branch and merge) history.

Cause

The option Show integrated changelists in committed changes is enabled by default. It adds the -i flag to the command that loads the changelists:

p4 changes -s submitted -i -t -l -m 100 <workspace root>/...

With -i, the Perforce server also collects the changelists that changed the source files of every integration into the workspace root. The server builds this set before it applies the -m limit, so on a branched depot the request exceeds MaxResults even when only 100 changelists are requested.

Resolution

1. Open Settings | Version Control | Perforce.
2. Clear Show integrated changelists in committed changes.
3. Click OK.
4. In the Repository tab, click Refresh.

With the option cleared, the Repository and Incoming tabs show the integration changelists themselves, but not the original changelists that they brought in from other branches.

If the error persists, the request is too large even without -i:

1. In the Repository tab, click Clear (the trash can icon).
2. Click Refresh. The first load after a clear requests a limited number of changelists. Set a lower value in Changelists to cache initially in the VCS History Cache Settings dialog that opens.

To see the exact command that fails, select Dump Perforce Commands in Settings | Version Control | Perforce, set a file in Log File, and click Refresh again. The log file contains every p4 command with its output.

The IDE does not fall back to a smaller request when the server rejects this one. Track the fix in Perforce Repository and Incoming tabs stay empty when p4 changes -i exceeds MaxResults.