[GitHub] [iceberg] rdblue commented on a change in pull request #1508: Use schema at the time of the snapshot when reading a snapshot.

[GitBox]

rdblue commented on a change in pull request #1508:
URL: https://github.com/apache/iceberg/pull/1508#discussion_r496938533



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File path: spark2/src/main/java/org/apache/iceberg/spark/source/Reader.java
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@@ -165,13 +165,23 @@
           TableProperties.PARQUET_BATCH_SIZE, 
TableProperties.PARQUET_BATCH_SIZE_DEFAULT));
   }
 
+  private Schema getTableSchema() {
+    if (snapshotId != null) {
+      return table.schemaForSnapshot(snapshotId);
+    } else if (asOfTimestamp != null) {
+      return table.schemaForSnapshotAsOfTime(asOfTimestamp);
+    } else {
+      return table.schema();
+    }
+  }
+
   private Schema lazySchema() {
     if (schema == null) {
       if (requestedSchema != null) {
         // the projection should include all columns that will be returned, 
including those only used in filters
-        this.schema = SparkSchemaUtil.prune(table.schema(), requestedSchema, 
filterExpression(), caseSensitive);
+        this.schema = SparkSchemaUtil.prune(getTableSchema(), requestedSchema, 
filterExpression(), caseSensitive);
       } else {
-        this.schema = table.schema();
+        this.schema = getTableSchema();

Review comment:
       In addition to updates here, we will need to update schema handling in 
`BaseTableScan` so that the projection returned by the scan is based on the 
schema of the `Snapshot` that will be scanned.




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