paul-rogers commented on a change in pull request #1985: DRILL-7565: ANALYZE
TABLE ... REFRESH METADATA does not work for empty Parquet files
URL: https://github.com/apache/drill/pull/1985#discussion_r379850140
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File path:
exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/ScanBatch.java
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@@ -237,6 +238,18 @@ private IterOutcome internalNext() {
logger.trace("currentReader.next return recordCount={}", recordCount);
Preconditions.checkArgument(recordCount >= 0, "recordCount from
RecordReader.next() should not be negative");
boolean isNewSchema = mutator.isNewSchema();
+ // adds additional record for the case of making scan for obtaining
metadata if required
+ if (implicitValues != null) {
+ String projectMetadataColumn =
context.getOptions().getOption(ExecConstants.IMPLICIT_PROJECT_METADATA_COLUMN_LABEL).string_val;
+ if (recordCount > 0) {
+ // sets implicit value to false to signalize that some results were
returned and there is no need for creating additional record
Review comment:
signalize --> signal
Maybe add a comment somewhere explaining this "additional record" concept.
On the surface, it seems odd. Either a) we are scanning the data and must use
the schema from the data to achieve a consistent result, or b) we are gathering
stats, which will have its own schema, whatever it is.
I'm struggling to see when we'd want to add some "additional" "record" to a
scan. With the same schema as other records? Or, with a different schema?
Really could use explanation, please.
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