reuse FileMetaData

For the statscan dataset, parsing the file metadata takes ~30-40ms,
so stash it away for future re-use.

parquet/Makefile

@@ -5,7 +5,7 @@ CC = g++
 CFLAGS = -I ../sqlite -O3 -std=c++11 -Wall -fPIC -g
 PARQUET_LIB = $(PARQUET_CPP)/build/release/libparquet.a
 THRIFT_LIB = $(PARQUET_CPP)/thrift_ep/src/thrift_ep-install/lib/libthrift.a
-ARROW_LIB = $(PARQUET_CPP)/build/release/libarrow.so
+ARROW_LIB = /usr/local/lib/libarrow.so
 BOOST_LIB = /usr/lib/x86_64-linux-gnu/libboost_regex.so
 
 LDFLAGS = -O3 $(PARQUET_LIB) $(THRIFT_LIB) $(ARROW_LIB) $(BOOST_LIB)

parquet/parquet_cursor.cc

@@ -34,21 +34,15 @@ bool ParquetCursor::currentRowGroupSatisfiesTextFilter(Constraint constraint, st
   parquet::TypedRowGroupStatistics<parquet::DataType<parquet::Type::BYTE_ARRAY>>* stats =
     (parquet::TypedRowGroupStatistics<parquet::DataType<parquet::Type::BYTE_ARRAY>>*)_stats.get();
 
-  // TODO: parquet-cpp doesn't seem to support stats for UTF8?
-  // 1) empirically, the following is false on a few parquets I've tested
-  // 2) https://github.com/apache/parquet-cpp/blob/master/src/parquet/metadata.cc#L116 seems to say UTF8 not supported
-  // 3) OTOH, https://issues.apache.org/jira/browse/ARROW-1982 seems to say it's supported
   if(!stats->HasMinMax()) {
     return true;
   }
 
-  /*
   parquet::ByteArray min = stats->min();
   parquet::ByteArray max = stats->max();
   std::string minStr((const char*)min.ptr, min.len);
   std::string maxStr((const char*)max.ptr, max.len);
   printf("min=%s [%d], max=%s [%d]\n", minStr.data(), min.len, maxStr.data(), max.len);
-  */
 
   switch(constraint.getOperator()) {
     case Is:
@@ -483,7 +477,11 @@ void ParquetCursor::reset(std::vector<Constraint> constraints) {
   rowId = -1;
   // TODO: consider having a long lived handle in ParquetTable that can be borrowed
   // without incurring the cost of opening the file from scratch twice
-  reader = parquet::ParquetFileReader::OpenFile(table->file.data());
+  reader = parquet::ParquetFileReader::OpenFile(
+      table->file.data(),
+      true,
+      parquet::default_reader_properties(),
+      table->getMetadata());
 
   rowGroupId = -1;
   rowGroupSize = 0;

parquet/parquet_table.cc

@@ -4,6 +4,9 @@
 
 ParquetTable::ParquetTable(std::string file) {
   this->file = file;
+
+  std::unique_ptr<parquet::ParquetFileReader> reader = parquet::ParquetFileReader::OpenFile(file.data());
+  metadata = reader->metadata();
 }
 
 std::string ParquetTable::columnName(int i) {
@@ -13,7 +16,11 @@ std::string ParquetTable::columnName(int i) {
 }
 
 std::string ParquetTable::CreateStatement() {
-  std::unique_ptr<parquet::ParquetFileReader> reader = parquet::ParquetFileReader::OpenFile(file.data());
+  std::unique_ptr<parquet::ParquetFileReader> reader = parquet::ParquetFileReader::OpenFile(
+      file.data(),
+      true,
+      parquet::default_reader_properties(),
+      metadata);
   std::string text("CREATE TABLE x(");
   auto schema = reader->metadata()->schema();
 
@@ -129,3 +136,5 @@ std::string ParquetTable::CreateStatement() {
   text +=");";
   return text;
 }
+
+std::shared_ptr<parquet::FileMetaData> ParquetTable::getMetadata() { return metadata; }

parquet/parquet_table.h

@@ -3,15 +3,19 @@
 
 #include <vector>
 #include <string>
+#include "parquet/api/reader.h"
 
 class ParquetTable {
   std::vector<std::string> columnNames;
+  std::shared_ptr<parquet::FileMetaData> metadata;
+
 
 public:
   ParquetTable(std::string file);
   std::string CreateStatement();
   std::string file;
   std::string columnName(int idx);
+  std::shared_ptr<parquet::FileMetaData> getMetadata();
 };
 
 #endif