roachtest: allow stats mismatches in clearrange roachtest

Previously, the clearrange roachtest was the only place anywhere in
the CockroachDB codebase where we would assert on MVCC stats matching
between replicas. This would trip up and fail the clearrange roachtest
even in known cases of MVCC stats mismatches. This change removes the
code to assert on stats mismatches with consistency checks, but retains
the clearrange roachtest's use of aggressive consistency checks, so
mismatches in checksums computed on data in each replica will
continue to fatal the test.

Related to cockroachdb#93896.

Fixes cockroachdb#108726.

Epic: none

Release note: None

pkg/cmd/roachtest/tests/clearrange.go

@@ -78,7 +78,7 @@ func runClearRange(ctx context.Context, t test.Test, c cluster.Cluster, aggressi
 		// This slows down merges, so it might hide some races.
 		//
 		// NB: the below invocation was found to actually make it to the server at the time of writing.
-		settings.Env = append(settings.Env, []string{"COCKROACH_CONSISTENCY_AGGRESSIVE=true", "COCKROACH_ENFORCE_CONSISTENT_STATS=true"}...)
+		settings.Env = append(settings.Env, "COCKROACH_CONSISTENCY_AGGRESSIVE=true")
 	}
 
 	c.Start(ctx, t.L(), option.DefaultStartOpts(), settings)

pkg/kv/kvserver/replica_consistency.go

@@ -31,7 +31,6 @@ import (
 	"github.com/cockroachdb/cockroach/pkg/storage"
 	"github.com/cockroachdb/cockroach/pkg/storage/enginepb"
 	"github.com/cockroachdb/cockroach/pkg/storage/fs"
-	"github.com/cockroachdb/cockroach/pkg/util/envutil"
 	"github.com/cockroachdb/cockroach/pkg/util/hlc"
 	"github.com/cockroachdb/cockroach/pkg/util/log"
 	"github.com/cockroachdb/cockroach/pkg/util/protoutil"
@@ -43,22 +42,6 @@ import (
 	"github.com/cockroachdb/redact"
 )
 
-// fatalOnStatsMismatch, if true, turns stats mismatches into fatal errors. A
-// stats mismatch is the event in which
-//   - the consistency checker finds that all replicas are consistent
-//     (i.e. byte-by-byte identical)
-//   - the (identical) stats tracked in them do not correspond to a recomputation
-//     via the data, i.e. the stats were incorrect
-//   - ContainsEstimates==false, i.e. the stats claimed they were correct.
-//
-// Before issuing the fatal error, the cluster bootstrap version is verified.
-// Note that on clusters that originally got bootstrapped on older releases
-// (definitely 19.1, and likely also more recent ones) we know of the existence
-// of stats bugs, so it has to be expected to see the assertion fire there.
-//
-// This env var is intended solely for use in Cockroach Labs testing.
-var fatalOnStatsMismatch = envutil.EnvOrDefaultBool("COCKROACH_ENFORCE_CONSISTENT_STATS", false)
-
 // replicaChecksum contains progress on a replica checksum computation.
 type replicaChecksum struct {
 	// started is closed when the checksum computation has started. If the start
@@ -219,11 +202,6 @@ func (r *Replica) checkConsistencyImpl(
 		if !haveDelta {
 			return resp, nil
 		}
-		if delta.ContainsEstimates <= 0 && fatalOnStatsMismatch {
-			// We just found out that the recomputation doesn't match the persisted stats,
-			// so ContainsEstimates should have been strictly positive.
-			log.Fatalf(ctx, "found a delta of %+v", redact.Safe(delta))
-		}
 
 		// We've found that there's something to correct; send an RecomputeStatsRequest. Note that this
 		// code runs only on the lease holder (at the time of initiating the computation), so this work