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new 78b7aac GH-607: Specify handling for unrecognized logical types (#606)
78b7aac is described below
commit 78b7aacfada812dc969ca7f1976186eca23ebe49
Author: Divjot Arora <[email protected]>
AuthorDate: Thu Sep 3 13:55:07 2026 -0400
GH-607: Specify handling for unrecognized logical types (#606)
* Specify handling for unrecognized logical types
* update CONTRIBUTING.md
* address wordign
---
CONTRIBUTING.md | 5 +++--
LogicalTypes.md | 9 +++++++++
2 files changed, 12 insertions(+), 2 deletions(-)
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index f9fdf21..e193f6f 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -126,8 +126,9 @@ For the purposes of this discussion we classify features
into the following buck
the feature enabled can be read under an older version of the format, but
some metadata might be missing or performance might be suboptimal. Simply
phrased, forward compatible means all data can be read back in an older
- version of the format. New logical types are considered forward
- compatible despite the loss of semantic meaning.
+ version of the format. New logical types and new combinations of existing
+ logical/physical types are considered forward compatible despite the loss
+ of semantic meaning.
3. Forward incompatible. A file written under a newer version of the format
with
the feature enabled cannot be read under an older version of the format
(e.g.
diff --git a/LogicalTypes.md b/LogicalTypes.md
index f7fe984..8ec8f5b 100644
--- a/LogicalTypes.md
+++ b/LogicalTypes.md
@@ -40,6 +40,8 @@ according to well defined conversion rules.
### Compatibility
+#### ConvertedType
+
The Thrift definition of the metadata has two fields for logical types:
`ConvertedType` and `LogicalType`.
`ConvertedType` is an enum of all available annotations. Since Thrift enums
can't have additional type parameters,
it is cumbersome to define additional type parameters, like decimal scale and
precision
@@ -54,6 +56,13 @@ in case `LogicalType` annotations are not present. Parquet
writers must always w
`LogicalType` annotations where applicable, but must also write the
corresponding
`ConvertedType` annotations (if any) to maintain compatibility with old
readers.
+#### Unsupported Logical Types
+
+When reading a file written by a newer writer that contains an unrecognized
logical type or an
+unrecognized logical/physical type combination on a column, readers should
ignore both the logical
+type annotation and column order for that column. Only the physical type
information should be used
+to process the column's data.
+
Compatibility considerations are mentioned for each annotation in the
corresponding section.
## String Types
