[GitHub] arina-ielchiieva closed pull request #976: DRILL-5797: Choose parquet reader from read columns

[GitBox <gi...@apache.org>]

arina-ielchiieva closed pull request #976: DRILL-5797: Choose parquet reader from read columns
URL: https://github.com/apache/drill/pull/976
 
 
   

This is a PR merged from a forked repository.
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the sake of provenance:

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diff --git a/exec/java-exec/src/main/java/org/apache/drill/exec/store/parquet/ParquetScanBatchCreator.java b/exec/java-exec/src/main/java/org/apache/drill/exec/store/parquet/ParquetScanBatchCreator.java
index 60179482fc3..82764285e99 100644
--- a/exec/java-exec/src/main/java/org/apache/drill/exec/store/parquet/ParquetScanBatchCreator.java
+++ b/exec/java-exec/src/main/java/org/apache/drill/exec/store/parquet/ParquetScanBatchCreator.java
@@ -26,6 +26,8 @@
 import com.google.common.base.Stopwatch;
 import com.google.common.collect.Maps;
 import org.apache.drill.common.exceptions.ExecutionSetupException;
+import org.apache.drill.common.expression.PathSegment;
+import org.apache.drill.common.expression.SchemaPath;
 import org.apache.drill.exec.ExecConstants;
 import org.apache.drill.exec.ops.FragmentContext;
 import org.apache.drill.exec.ops.OperatorContext;
@@ -37,12 +39,15 @@
 import org.apache.drill.exec.store.dfs.DrillFileSystem;
 import org.apache.drill.exec.store.parquet.columnreaders.ParquetRecordReader;
 import org.apache.drill.exec.store.parquet2.DrillParquetReader;
+import org.apache.drill.exec.util.Utilities;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.fs.Path;
 import org.apache.parquet.column.ColumnDescriptor;
 import org.apache.parquet.hadoop.CodecFactory;
 import org.apache.parquet.hadoop.ParquetFileReader;
 import org.apache.parquet.hadoop.metadata.ParquetMetadata;
+import org.apache.parquet.io.InvalidRecordException;
+import org.apache.parquet.schema.GroupType;
 import org.apache.parquet.schema.MessageType;
 import org.apache.parquet.schema.Type;
 
@@ -119,7 +124,7 @@ public ScanBatch getBatch(FragmentContext context, ParquetRowGroupScan rowGroupS
         if (logger.isDebugEnabled()) {
           logger.debug(containsCorruptDates.toString());
         }
-        if (!context.getOptions().getOption(ExecConstants.PARQUET_NEW_RECORD_READER).bool_val && !isComplex(footers.get(e.getPath()))) {
+        if (!context.getOptions().getOption(ExecConstants.PARQUET_NEW_RECORD_READER).bool_val && !isComplex(footers.get(e.getPath()), rowGroupScan.getColumns())) {
           readers.add(
               new ParquetRecordReader(
                   context, e.getPath(), e.getRowGroupIndex(), e.getNumRecordsToRead(), fs,
@@ -156,20 +161,49 @@ public ScanBatch getBatch(FragmentContext context, ParquetRowGroupScan rowGroupS
     return new ScanBatch(rowGroupScan, context, oContext, readers, implicitColumns);
   }
 
-  private static boolean isComplex(ParquetMetadata footer) {
+  private static boolean isComplex(ParquetMetadata footer, List<SchemaPath> columns) {
+    /**
+     * ParquetRecordReader is not able to read any nested columns and is not able to handle repeated columns.
+     * It only handles flat column and optional column.
+     * If it is a wildcard query, we check every columns in the metadata.
+     * If not, we only check the projected columns.
+     * We only check the first level columns because :
+     *   - if we need a.b, it means a is a complex type, no need to check b as we don't handle complex type.
+     *   - if we need a[10], a is repeated, ie its repetiton level is greater than 0
+     *   - if we need a, it is at the first level of the schema.
+     */
     MessageType schema = footer.getFileMetaData().getSchema();
-
-    for (Type type : schema.getFields()) {
-      if (!type.isPrimitive()) {
-        return true;
+    if (Utilities.isStarQuery(columns)) {
+      for (Type type : schema.getFields()) {
+        if (!type.isPrimitive()) {
+          return true;
+        }
       }
-    }
-    for (ColumnDescriptor col : schema.getColumns()) {
-      if (col.getMaxRepetitionLevel() > 0) {
-        return true;
+      for (ColumnDescriptor col : schema.getColumns()) {
+        if (col.getMaxRepetitionLevel() > 0) {
+          return true;
+        }
+      }
+      return false;
+    } else {
+      for (SchemaPath column : columns) {
+        if (isColumnComplex(schema, column)) {
+          return true;
+        }
       }
+      return false;
+    }
+  }
+
+  private static boolean isColumnComplex(GroupType grouptype, SchemaPath column) {
+    try {
+      Type type = grouptype.getType(column.getRootSegment().getPath().toLowerCase());
+      return type.isRepetition(Type.Repetition.REPEATED) || !type.isPrimitive();
+    }
+    catch(InvalidRecordException e) {
+      //if the type does exist, we will fill with null so it is a simple type.
+      return false;
     }
-    return false;
   }
 
 }


 

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