238 lines
7.4 KiB
C++
238 lines
7.4 KiB
C++
#include "parquet_cursor.h"
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ParquetCursor::ParquetCursor(ParquetTable* table) {
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this->table = table;
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this->rowId = -1;
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// TODO: consider having a long lived handle in ParquetTable that can be borrowed
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// without incurring the cost of opening the file from scratch twice
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this->reader = parquet::ParquetFileReader::OpenFile(this->table->file.data());
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this->rowGroupId = -1;
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// TODO: handle the case where rowgroups have disjoint schemas?
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// TODO: or at least, fail fast if detected
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this->rowsLeftInRowGroup = 0;
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this->numRows = reader->metadata()->num_rows();
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this->numRowGroups = reader->metadata()->num_row_groups();
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}
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bool ParquetCursor::nextRowGroup() {
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// TODO: skip row groups that cannot satisfy the constraints
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if((this->rowGroupId + 1) >= this->numRowGroups)
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return false;
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rowGroupId++;
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rowGroupMetadata = this->reader->metadata()->RowGroup(0);
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rowsLeftInRowGroup = rowGroupMetadata->num_rows();
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rowGroup = reader->RowGroup(rowGroupId);
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for(unsigned int i = 0; i < scanners.size(); i++)
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scanners[i] = NULL;
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while(types.size() < (unsigned int)rowGroupMetadata->num_columns()) {
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types.push_back(rowGroupMetadata->schema()->Column(0)->physical_type());
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}
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while(logicalTypes.size() < (unsigned int)rowGroupMetadata->num_columns()) {
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logicalTypes.push_back(rowGroupMetadata->schema()->Column(0)->logical_type());
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}
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for(unsigned int i = 0; i < (unsigned int)rowGroupMetadata->num_columns(); i++) {
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types[i] = rowGroupMetadata->schema()->Column(i)->physical_type();
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logicalTypes[i] = rowGroupMetadata->schema()->Column(i)->logical_type();
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}
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return true;
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}
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void ParquetCursor::next() {
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if(rowsLeftInRowGroup == 0) {
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if(!nextRowGroup()) {
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// put rowId over the edge so eof returns true
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rowId++;
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return;
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}
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}
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rowsLeftInRowGroup--;
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rowId++;
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}
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int ParquetCursor::getRowId() {
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return rowId;
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}
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bool ParquetCursor::eof() {
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return rowId >= numRows;
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}
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void ParquetCursor::ensureColumn(int col) {
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// need to ensure a scanner exists (and skip the # of rows in the rowgroup)
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while((unsigned int)col >= scanners.size()) {
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scanners.push_back(std::shared_ptr<parquet::Scanner>());
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colRows.push_back(-1);
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colNulls.push_back(false);
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colIntValues.push_back(0);
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colDoubleValues.push_back(0);
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colByteArrayValues.push_back(parquet::ByteArray());
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}
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if(scanners[col].get() == NULL) {
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std::shared_ptr<parquet::ColumnReader> colReader = rowGroup->Column(col);
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scanners[col] = parquet::Scanner::Make(colReader);
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// TODO: potentially skip rows if rowsLeftInRowGroup != rowGroupMetadata->num_rows()
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}
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// Actually fetch a value, stash data in colRows, colNulls, colValues
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if(colRows[col] != rowId) {
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colRows[col] = rowId;
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bool wasNull = false;
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switch(types[col]) {
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case parquet::Type::INT32:
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{
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parquet::Int32Scanner* s = (parquet::Int32Scanner*)scanners[col].get();
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int rv = 0;
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if(s->NextValue(&rv, &wasNull)) {
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colIntValues[col] = rv;
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} else {
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throw std::invalid_argument("unexpectedly lacking a next value");
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}
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break;
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}
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case parquet::Type::FLOAT:
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{
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parquet::FloatScanner* s = (parquet::FloatScanner*)scanners[col].get();
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float rv = 0;
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if(s->NextValue(&rv, &wasNull)) {
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colDoubleValues[col] = rv;
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} else {
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throw std::invalid_argument("unexpectedly lacking a next value");
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}
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break;
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}
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case parquet::Type::DOUBLE:
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{
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parquet::DoubleScanner* s = (parquet::DoubleScanner*)scanners[col].get();
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double rv = 0;
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if(s->NextValue(&rv, &wasNull)) {
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colDoubleValues[col] = rv;
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} else {
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throw std::invalid_argument("unexpectedly lacking a next value");
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}
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break;
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}
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case parquet::Type::BYTE_ARRAY:
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{
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parquet::ByteArrayScanner* s = (parquet::ByteArrayScanner*)scanners[col].get();
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if(!s->NextValue(&colByteArrayValues[col], &wasNull)) {
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throw std::invalid_argument("unexpectedly lacking a next value");
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}
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break;
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}
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case parquet::Type::INT96:
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{
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// INT96 tracks a date with nanosecond precision, convert to ms since epoch.
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// ...see https://github.com/apache/parquet-format/pull/49 for more
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//
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// First 8 bytes: nanoseconds into the day
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// Last 4 bytes: Julian day
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// To get nanoseconds since the epoch:
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// (julian_day - 2440588) * (86400 * 1000 * 1000 * 1000) + nanoseconds
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parquet::Int96Scanner* s = (parquet::Int96Scanner*)scanners[col].get();
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parquet::Int96 rv;
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rv.value[0] = 0;
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rv.value[1] = 0;
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rv.value[2] = 0;
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if(s->NextValue(&rv, &wasNull)) {
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__int128 ns = rv.value[0] + ((unsigned long)rv.value[1] << 32);
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__int128 julianDay = rv.value[2];
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__int128 nsSinceEpoch = (julianDay - 2440588);
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nsSinceEpoch *= 86400;
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nsSinceEpoch *= 1000 * 1000 * 1000;
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nsSinceEpoch += ns;
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nsSinceEpoch /= 1000000;
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colIntValues[col] = nsSinceEpoch;
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} else {
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throw std::invalid_argument("unexpectedly lacking a next value");
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}
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break;
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}
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case parquet::Type::INT64:
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{
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parquet::Int64Scanner* s = (parquet::Int64Scanner*)scanners[col].get();
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long rv = 0;
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if(s->NextValue(&rv, &wasNull)) {
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colIntValues[col] = rv;
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} else {
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throw std::invalid_argument("unexpectedly lacking a next value");
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}
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break;
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}
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case parquet::Type::BOOLEAN:
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{
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parquet::BoolScanner* s = (parquet::BoolScanner*)scanners[col].get();
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bool rv = false;
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if(s->NextValue(&rv, &wasNull)) {
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colIntValues[col] = rv ? 1 : 0;
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} else {
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throw std::invalid_argument("unexpectedly lacking a next value");
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}
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break;
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}
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case parquet::Type::FIXED_LEN_BYTE_ARRAY:
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{
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parquet::FixedLenByteArrayScanner* s = (parquet::FixedLenByteArrayScanner*)scanners[col].get();
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parquet::FixedLenByteArray flba;
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if(s->NextValue(&flba, &wasNull)) {
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colByteArrayValues[col].ptr = flba.ptr;
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// TODO: cache this
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colByteArrayValues[col].len = rowGroupMetadata->schema()->Column(col)->type_length();
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} else {
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throw std::invalid_argument("unexpectedly lacking a next value");
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}
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break;
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}
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default:
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// Should be impossible to get here as we should have forbidden this at
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// CREATE time -- maybe file changed underneath us?
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std::ostringstream ss;
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ss << __FILE__ << ":" << __LINE__ << ": column " << col << " has unsupported type: " <<
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parquet::TypeToString(types[col]);
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throw std::invalid_argument(ss.str());
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break;
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}
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colNulls[col] = wasNull;
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}
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}
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bool ParquetCursor::isNull(int col) {
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return colNulls[col];
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}
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int ParquetCursor::getInt32(int col) {
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return colIntValues[col];
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}
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long ParquetCursor::getInt64(int col) {
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return colIntValues[col];
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}
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double ParquetCursor::getDouble(int col) {
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return colDoubleValues[col];
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}
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parquet::ByteArray* ParquetCursor::getByteArray(int col) {
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return &colByteArrayValues[col];
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}
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parquet::Type::type ParquetCursor::getPhysicalType(int col) {
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return types[col];
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}
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parquet::LogicalType::type ParquetCursor::getLogicalType(int col) {
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return logicalTypes[col];
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}
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