krisnaru commented on code in PR #14355:
URL: https://github.com/apache/iceberg/pull/14355#discussion_r3186041706
##########
core/src/main/java/org/apache/iceberg/RewriteTablePathUtil.java:
##########
@@ -608,6 +610,43 @@ private static PositionDelete newPositionDeleteRecord(
return delete;
}
+ /**
+ * Lookup the longest matching prefix mapping for a given path.
+ *
+ * @param path the path to find a prefix mapping for
+ * @param prefixMappings map of source prefix to target prefix mappings
+ * @return the Map.Entry with the longest matching source prefix, or null if
no match found
+ */
+ public static Map.Entry<String, String> lookupPrefixMappings(
+ String path, Map<String, String> prefixMappings) {
+ if (prefixMappings == null || prefixMappings.isEmpty() || path == null) {
+ return null;
+ }
+
+ // Sort entries by key length in descending order to find the longest
matching prefix
+ return prefixMappings.entrySet().stream()
+ .filter(entry -> path.startsWith(entry.getKey()))
+ .max(java.util.Comparator.comparing(entry ->
entry.getKey().length()))
+ .orElse(null);
Review Comment:
If you have multiple prefix mappings like:
```
s3://bucket/warehouse/ → s3://new-bucket/warehouse/
s3://bucket/warehouse/db/tbl/ → s3://other-bucket/data/
```
And a file path is s3://bucket/warehouse/db/tbl/data.parquet, both
prefixes match (both are valid startsWith matches). By picking the longest
matching prefix, you ensure the most specific mapping wins — the
file gets rewritten to s3://other-bucket/data/data.parquet rather than
s3://new-bucket/warehouse/db/tbl/data.parquet.
Without the length-based sorting, the result would be non-deterministic
(depends on map iteration order) and could apply the wrong, less-specific
prefix.
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