Bug hunting

presto-main/src/main/java/com/facebook/presto/server/protocol/Query.java

@@ -22,6 +22,7 @@
 import com.facebook.presto.client.StatementStats;
 import com.facebook.presto.common.ErrorCode;
 import com.facebook.presto.common.Page;
+import com.facebook.presto.common.block.Block;
 import com.facebook.presto.common.block.BlockEncodingSerde;
 import com.facebook.presto.common.transaction.TransactionId;
 import com.facebook.presto.common.type.BooleanType;
@@ -445,6 +446,19 @@ else if (queryManager.getQueryRetryCount(queryId) == 1 && retryQueryWithHistoryB
  queryResults.getUpdateCount());
  }
 
+ private static void validateBlockSizesInPage(Page page)
+ {
+ // debugging
+ for (int channel = 0; channel < page.getChannelCount(); channel++) {
+ Block block = page.getBlock(channel);
+ if (block.getPositionCount() != page.getPositionCount()) {
+ throw new IllegalArgumentException(
+ format("Wrongly sized block: channel: %d block poition count: %d page position count: %d %s",
+ channel, block.getPositionCount(), page.getPositionCount(), block.getClass().getCanonicalName()));
+ }
+ }
+ }
+
  private synchronized QueryResults getNextResult(long token, UriInfo uriInfo, String scheme, DataSize targetResultSize, boolean binaryResults)
  {
  // check if the result for the token have already been created
@@ -502,6 +516,7 @@ private synchronized QueryResults getNextResult(long token, UriInfo uriInfo, Str
  }
 
  Page page = serde.deserialize(serializedPage);
+ validateBlockSizesInPage(page);
  bytes += page.getLogicalSizeInBytes();
  rows += page.getPositionCount();
  pages.add(new RowIterable(session.toConnectorSession(), types, page));

presto-main/src/main/java/com/facebook/presto/server/protocol/RowIterable.java

@@ -25,6 +25,7 @@
 import java.util.Iterator;
 import java.util.List;
 
+import static java.lang.String.format;
 import static java.util.Objects.requireNonNull;
 
 class RowIterable
@@ -39,6 +40,8 @@ class RowIterable
  this.session = session;
  this.types = ImmutableList.copyOf(requireNonNull(types, "types is null"));
  this.page = requireNonNull(page, "page is null");
+
+ validateBlockSizesInPage(page);
  }
 
  @Override
@@ -60,6 +63,8 @@ private RowIterator(ConnectorSession session, List<Type> types, Page page)
  this.session = session;
  this.types = types;
  this.page = page;
+
+ validateBlockSizesInPage(page);
  }
 
  @Override
@@ -74,9 +79,29 @@ protected List<Object> computeNext()
  for (int channel = 0; channel < page.getChannelCount(); channel++) {
  Type type = types.get(channel);
  Block block = page.getBlock(channel);
+ // Caused by: java.lang.IllegalArgumentException: Invalid position 1 in block with 1 positions
+ // why does block onlly have one position when we're asking for at least 12?
+ // It's not an off by one error. It's that there's only one row ID in the block.
+ // That's why it works with LIMIT 1 and not LIMIT 2
+ // maybe an issue with compressed dictionary blocks or something like that?
+ // only some tables/rows use dictionary blocks
+ // and exception changes from LIMIT 2 to 3
  values.add(type.getObjectValue(session.getSqlFunctionProperties(), block, position));
  }
  return Collections.unmodifiableList(values);
  }
  }
+
+ private static void validateBlockSizesInPage(Page page)
+ {
+ // debugging
+ for (int channel = 0; channel < page.getChannelCount(); channel++) {
+ Block block = page.getBlock(channel);
+ if (block.getPositionCount() != page.getPositionCount()) {
+ throw new IllegalArgumentException(
+ format("Wrongly sized block: channel: %d block poition count: %d page position count: %d %s",
+ channel, block.getPositionCount(), page.getPositionCount(), block.getClass().getCanonicalName()));
+ }
+ }
+ }
 }