dgraph-io/badger · info

errFillTables

errFillTables

Error message

Unable to fill tables

What it means

errFillTables is a sentinel error returned by doCompact when it cannot pick tables for a compaction — meaning there may be enough tables queued but a def could not be built (e.g. target level busy or no candidates). Badger treats it as benign: callers explicitly ignore it and do not report it to end users.

Source

Thrown at levels.go:1601

	if cd.thisLevel.level != 0 && len(newTables) > 2*s.kv.opt.LevelSizeMultiplier {
		s.kv.opt.Infof("This Range (numTables: %d)\nLeft:\n%s\nRight:\n%s\n",
			len(cd.top), hex.Dump(cd.thisRange.left), hex.Dump(cd.thisRange.right))
		s.kv.opt.Infof("Next Range (numTables: %d)\nLeft:\n%s\nRight:\n%s\n",
			len(cd.bot), hex.Dump(cd.nextRange.left), hex.Dump(cd.nextRange.right))
	}
	return nil
}

func tablesToString(tables []*table.Table) []string {
	var res []string
	for _, t := range tables {
		res = append(res, fmt.Sprintf("%05d", t.ID()))
	}
	res = append(res, ".")
	return res
}

var errFillTables = errors.New("Unable to fill tables")

// doCompact picks some table on level l and compacts it away to the next level.
func (s *levelsController) doCompact(id int, p compactionPriority) error {
	l := p.level
	y.AssertTrue(l < s.kv.opt.MaxLevels) // Sanity check.
	if p.t.baseLevel == 0 {
		p.t = s.levelTargets()
	}

	_, span := otel.Tracer("").Start(context.TODO(), "Badger.Compaction")
	defer span.End()

	cd := compactDef{
		compactorId:  id,
		p:            p,
		t:            p.t,
		thisLevel:    s.levels[l],
		dropPrefixes: p.dropPrefixes,

View on GitHub (pinned to 2a001d466f)

Solutions

1. Nothing needed — this is expected flow control; do not log it as an error
2. If compactions never progress, check level sizes/badger info output and options (NumLevelZeroTables, baseLevelSize)
3. Match on the sentinel with errors.Is if you drive compaction manually

Example fix

// before
if err := db.lc.doCompact(173, p); err != nil {
    return err // wrongly surfaces benign errFillTables
}
// after
if err := db.lc.doCompact(173, p); err != nil {
    if errors.Is(err, errFillTables) {
        return nil // benign: nothing to compact right now
    }
    return err
}

// Go: treat errFillTables as success when driving compactions manually
if err := db.lc.doCompact(id, p); errors.Is(err, errFillTables) { /* nothing to do */ }

// Go
switch err := db.lc.doCompact(id, p); {
case err == nil:
    // compacted
case errors.Is(err, errFillTables):
    // benign: no tables could be filled; do not report to users
default:
    log.Printf("compaction failed: %v", err)
}

When it happens

Trigger: doCompact runs (automatically or induced, e.g. db.go:635's level:0/score:1.73 trigger) and runCompactDef/fillTables returns without building a compaction def; also observed via close() path per the declaration.

Common situations: Normal operation when compaction candidates are transiently unavailable; heavy write load delaying compaction; induced test compactions that find nothing to do.

Related errors

• ErrNoRewrite
• Cannot have 1 compactor. Need at least 2
• error during flatten in StreamWriter: %w
• Base level can't be zero.
• Filesizes cannot be zero. Targets are not set

AI-assisted analysis of dgraph-io/badger@2a001d466f (2026-09-05). Data as JSON: /api/errors/58349a0ac0585016. Report an issue: GitHub.