feat(parquet): apply column default values when reading missing fields (2/4)#792
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| Result<std::shared_ptr<::arrow::Buffer>> ToArrowBuffer( | ||
| const std::vector<uint8_t>& bytes) { |
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add arrow::MemoryPool* as an input parameter.
| Status AppendDefaultToBuilder(const Literal& literal, ::arrow::ArrayBuilder* builder) { | ||
| ICEBERG_ASSIGN_OR_RAISE(std::shared_ptr<::arrow::Scalar> scalar, | ||
| ToArrowScalar(literal)); | ||
| if (!scalar->type->Equals(*builder->type())) { |
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Could we mirror MakeDefaultArray's extension handling here? ToArrowScalar(UUID) returns fixed_size_binary(16), and Scalar::CastTo(arrow.uuid()) is not implemented in Arrow, so using this helper with an arrow.uuid builder would fail.
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Thanks for catching this, I took a second look and this method is not used in parquet(but avro in the poc). It seems that it got accidentally added to this pr. I will include the fix in avro pr later.
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…s (2/4) When a column is present in the read schema but missing from a Parquet data file (written before the column existed), fill it with the column's v3 initial-default instead of null. Adds a shared Arrow materializer (arrow/literal_util) that turns a Literal into an Arrow scalar/array, and a kDefault projection branch in the Parquet schema/data projection paths. The materializer wraps the storage array in the extension type for extension types such as `arrow.uuid` (compute::Cast has no storage->extension kernel). Part 2 of the v3 column-default-values work (POC apache#731), built on the schema support merged in apache#746.
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Co-authored-by: Gang Wu <ustcwg@gmail.com>
The ToArrowScalar default argument was removed, so update the test call sites to pass arrow::default_memory_pool() explicitly.
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Thank you, @huan233usc! |
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What
Part 2 of 4 of Iceberg v3 column default-value support (POC #731), built on the
schema-layer support merged in #746.
When a column is present in the read (table) schema but absent from a Parquet
data file — because the column was added after those rows were written — fill it
with the column's v3
initial-defaultinstead ofnull.Changes
arrow/literal_util(new): a shared Arrow materializer that converts aLiteralto an Arrow scalar (ToArrowScalar), to a constant-filled array(
MakeDefaultArray), or appends it once to a builder(
AppendDefaultToBuilder). Covers all primitive types, includingdecimal/uuid/fixed and the four timestamp variants.
parquet_schema_util.cc): when a field is missingfrom the file and carries an
initial-default, project it asFieldProjection::Kind::kDefault, mirroring the genericschema_util.ccpathalready merged in feat(schema): represent, serialize and validate v3 column default values (1/4) #746.
parquet_data_util.cc): materialize thekDefaultbranchvia
MakeDefaultArray.Tests
literal_util_test: scalar/array/builder conversion across primitive types,null and narrowing-sentinel handling, and casting to the target Arrow type.
parquet_data_test:ProjectRecordBatchfills missing required and optionaldefault fields, including a nested struct.
parquet_test: end-to-end — write a file with an old schema, then read itthrough
ReaderFactoryRegistrywith an evolved schema carrying defaults(
ReadMissingFieldsWithDefaults).Stack
addColumn/updateColumnDefault(follows)