parquet-cli reports nested columns as null

Reproduisez le problème avec Parquet CLI 1.15.0 en utilisant parquet schema, parquet dictionary -c subjects.list.element et cat ou head sur catalog.parquet. Comparez les valeurs de la colonne imbriquée signalées par la commande de dictionnaire avec les enregistrements affichés et inspectez le chemin de parquet-cli qui gère ces commandes. La tâche est terminée lorsque cat et head affichent des tableaux imbriqués au lieu de les afficher incorrectement comme null.

Describe the bug, including details regarding any error messages, version, and platform.

Using Parquet CLI 1.15.0 via Mac Homebrew, I noticed some surprising behaviour with the parquet-cli and nested columns.

parquet schema catalog.parquet returns a schema showing the nested types (I've trimmed the field list slightly):

{
  "type" : "record",
  "name" : "schema",
  "fields" : [ {
    "name" : "item_id",
    "type" : "string"
  }, {
    "name" : "title",
    "type" : [ "null", "string" ],
    "default" : null
  }, {
    "name" : "language",
    "type" : [ "null", "string" ],
    "default" : null
  }, {
    "name" : "subjects",
    "type" : [ "null", {
      "type" : "array",
      "items" : {
        "type" : "record",
        "name" : "list",
        "fields" : [ {
          "name" : "element",
          "type" : "string"
        } ]
      }
    } ],
    "default" : null
  }, {
    "name" : "authors",
    "type" : [ "null", {
      "type" : "array",
      "items" : {
        "type" : "record",
        "name" : "list",
        "namespace" : "list2",
        "fields" : [ {
          "name" : "element",
          "type" : "string"
        } ]
      }
    } ],
    "default" : null
  } ]
}

parquet dictionary -c subjects.list.element catalog.parquet will return the expected values for those fields as well:

Row group 0 dictionary for "subjects.list.element":
     0: "Bestsellers"
     1: "Biography"
     2: "Fantasy Fiction"
     3: "Music Theory"
     4: "Disability"
     5: "Family"
     6: "Young Adult"

However, when using cat or head to display the file contents those fields are displayed as null:

{"bmc_id": "id1", "title": null, "language": "en", "subjects": null, "authors": null}
{"bmc_id": "id2", "title": null, "language": "en", "subjects": null, "authors": null,}
{"bmc_id": "id3", "title": null, "language": "en", "subjects": null, "authors": null}

Other tools like PyArrow or Pandas do display those values as arrays. I created this as a bug because it looks like it's working and if those fields are nullable, there's no way to tell whether the null value is correct.

Component(s)

No response