apache/druid · error · IAE

If a local input source sets property %s, it must also set p

Error message

If a local input source sets property %s, it must also set property %s

What it means

A local input source's filter only applies to files discovered under baseDir, so validate rejects a config that sets filter without baseDir. Thrown as IllegalArgumentException when filter is non-empty but baseDir is absent.

Source

Thrown at server/src/main/java/org/apache/druid/catalog/model/table/LocalInputSourceDefn.java:95

  }

  @Override
  public void validate(ResolvedExternalTable table)
  {
    final Map<String, Object> sourceMap = new HashMap<>(table.inputSourceMap);
    final boolean hasBaseDir = sourceMap.containsKey(BASE_DIR_FIELD);
    final boolean hasFiles = !CollectionUtils.isNullOrEmpty(CatalogUtils.safeGet(sourceMap, FILES_FIELD, List.class));
    final boolean hasFilter = !Strings.isNullOrEmpty(CatalogUtils.getString(sourceMap, FILTER_FIELD));

    if (!hasBaseDir && !hasFiles) {
      throw new IAE(
          "A local input source requires one property of %s or %s",
          BASE_DIR_FIELD,
          FILES_FIELD
      );
    }
    if (!hasBaseDir && hasFilter) {
      throw new IAE(
          "If a local input source sets property %s, it must also set property %s",
          FILTER_FIELD,
          BASE_DIR_FIELD
      );
    }
    if (hasBaseDir && hasFiles) {
      throw new IAE(
          "A local input source accepts only one of %s or %s",
          BASE_DIR_FIELD,
          FILES_FIELD
      );
    }
    super.validate(table);
  }

  @Override
  protected List<ParameterDefn> adHocTableFnParameters()
  {

View on GitHub (pinned to 9b90983fd2)

Solutions

Add the baseDir property alongside filter
Or remove the filter if you intend to use an explicit files list (filter does not apply to it)
Restructure the config so discovery uses baseDir + filter instead of files

Example fix

// before
{"type":"local","files":["/data/a.csv"],"filter":"*.csv"}
// after
{"type":"local","baseDir":"/data","filter":"*.csv"}

Defensive patterns

Strategy: validation

Validate before calling

if (src.get("filter") != null && !((String) src.get("filter")).isEmpty()
    && !src.containsKey("baseDir")) {
  throw new IllegalArgumentException("filter requires baseDir");
}

Try / catch

try { defn.validate(table); } catch (IAE e) { if (e.getMessage().contains("must also set property")) { /* add baseDir or drop filter */ } else { throw e; } }

Prevention

Remember filter only works with baseDir-based discovery
When using an explicit files list, do not set filter
Document this constraint in config templates

When it happens

Trigger: Validating a local input source where the filter field is set, the baseDir field is missing, and (per the first check) files is provided or the baseDir/files check already passed — specifically the !hasBaseDir && hasFilter case.

Common situations: User adds a filter pattern to a files-based local source assuming it filters that list; config template that emits filter but skips baseDir when a path variable is empty.

Related errors

AI-assisted analysis of apache/druid@9b90983fd2 (2026-09-07). Data as JSON: /api/errors/c78a9f095f160402. Report an issue: GitHub.