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mirror of https://github.com/mariadb-corporation/mariadb-columnstore-engine.git synced 2025-04-18 21:44:02 +03:00
drrtuy 8ae5a3da40
Fix/mcol 5787 rgdata buffer max size dev (#3325)
* fix(rowgroup): RGData now uses uint64_t counter for the fixed sizes columns data buf.
	The buffer can utilize > 4GB RAM that is necessary for PM side join.
	RGData ctor uses uint32_t allocating data buffer.
 	This fact causes implicit heap overflow.

* feat(bytestream,serdes): BS buffer size type is uint64_t
	This necessary to handle 64bit RGData, that comes as
	a separate patch. The pair of patches would allow to
	have PM joins when SmallSide size > 4GB.

* feat(bytestream,serdes): Distribute BS buf size data type change to avoid implicit data type narrowing

* feat(rowgroup): this returns bits lost during cherry-pick. The bits lost caused the first RGData::serialize to crash a process
2024-11-09 19:44:02 +00:00

901 lines
21 KiB
C++

/* Copyright (C) 2014 InfiniDB, Inc.
Copyright (C) 2019 MariaDB Corporation
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; version 2 of
the License.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
MA 02110-1301, USA. */
#include "bytestream.h"
#define _CRT_RAND_S // for win rand_s
#include <unistd.h>
#include <boost/filesystem.hpp>
#include "configcpp.h"
#include "joinpartition.h"
#include "tuplejoiner.h"
#include "atomicops.h"
#include "installdir.h"
using namespace std;
using namespace utils;
using namespace rowgroup;
using namespace messageqcpp;
using namespace logging;
namespace joiner
{
// FIXME: Possible overflow, we have to null it after clearing files.
uint64_t uniqueNums = 0;
JoinPartition::JoinPartition()
{
compressor.reset(new compress::CompressInterfaceSnappy());
}
/* This is the ctor used by THJS */
JoinPartition::JoinPartition(const RowGroup& lRG, const RowGroup& sRG, const vector<uint32_t>& smallKeys,
const vector<uint32_t>& largeKeys, bool typeless, bool antiWMN, bool hasFEFilter,
uint64_t totalUMMemory, uint64_t partitionSize, uint32_t maxPartitionTreeDepth)
: smallRG(sRG)
, largeRG(lRG)
, smallKeyCols(smallKeys)
, largeKeyCols(largeKeys)
, typelessJoin(typeless)
, nextPartitionToReturn(0)
, htSizeEstimate(0)
, htTargetSize(partitionSize)
, rootNode(true)
, canSplit(true)
, antiWithMatchNulls(antiWMN)
, needsAllNullRows(hasFEFilter)
, gotNullRow(false)
, totalBytesRead(0)
, totalBytesWritten(0)
, maxLargeSize(0)
, maxSmallSize(0)
, nextSmallOffset(0)
, nextLargeOffset(0)
, currentPartitionTreeDepth(0)
, maxPartitionTreeDepth(maxPartitionTreeDepth)
{
config::Config* config = config::Config::makeConfig();
string cfgTxt;
smallSizeOnDisk = largeSizeOnDisk = 0;
/* Debugging, rand() is used to simulate failures
time_t t = time(NULL);
srand(t);
*/
cfgTxt = config->getConfig("HashJoin", "TempFileCompression");
if (cfgTxt == "n" || cfgTxt == "N")
useCompression = false;
else
useCompression = true;
fileMode = false;
uniqueID = atomicops::atomicInc(&uniqueNums);
uint32_t tmp = uniqueID;
hashSeed = rand_r(&tmp);
hashSeed = hasher((char*)&hashSeed, sizeof(hashSeed), uniqueID);
hashSeed = hasher.finalize(hashSeed, sizeof(hashSeed));
// start with initial capacity = 2 * totalUMMemory
bucketCount = (totalUMMemory * 2) / htTargetSize + 1;
largeRG.initRow(&largeRow);
smallRG.initRow(&smallRow);
buckets.reserve(bucketCount);
string compressionType;
try
{
compressionType = config->getConfig("HashJoin", "TempFileCompressionType");
}
catch (...)
{
}
if (compressionType == "LZ4")
compressor.reset(new compress::CompressInterfaceLZ4());
else
compressor.reset(new compress::CompressInterfaceSnappy());
for (uint32_t i = 0; i < bucketCount; i++)
buckets.push_back(
boost::shared_ptr<JoinPartition>(new JoinPartition(*this, false, currentPartitionTreeDepth + 1)));
}
/* Ctor used by JoinPartition on expansion, creates JP's in filemode */
JoinPartition::JoinPartition(const JoinPartition& jp, bool splitMode, uint32_t currentPartitionTreeDepth)
: smallRG(jp.smallRG)
, largeRG(jp.largeRG)
, smallKeyCols(jp.smallKeyCols)
, largeKeyCols(jp.largeKeyCols)
, typelessJoin(jp.typelessJoin)
, bucketCount(jp.bucketCount)
, smallRow(jp.smallRow)
, largeRow(jp.largeRow)
, nextPartitionToReturn(0)
, htSizeEstimate(0)
, htTargetSize(jp.htTargetSize)
, rootNode(false)
, canSplit(true)
, antiWithMatchNulls(jp.antiWithMatchNulls)
, needsAllNullRows(jp.needsAllNullRows)
, gotNullRow(false)
, useCompression(jp.useCompression)
, totalBytesRead(0)
, totalBytesWritten(0)
, maxLargeSize(0)
, maxSmallSize(0)
, nextSmallOffset(0)
, nextLargeOffset(0)
, currentPartitionTreeDepth(currentPartitionTreeDepth)
, maxPartitionTreeDepth(jp.maxPartitionTreeDepth)
{
ostringstream os;
fileMode = true;
config::Config* config = config::Config::makeConfig();
filenamePrefix = config->getTempFileDir(config::Config::TempDirPurpose::Joins);
filenamePrefix += "/Columnstore-join-data-";
uniqueID = atomicops::atomicInc(&uniqueNums);
uint32_t tmp = uniqueID;
hashSeed = rand_r(&tmp);
hashSeed = hasher((char*)&hashSeed, sizeof(hashSeed), uniqueID);
hashSeed = hasher.finalize(hashSeed, sizeof(hashSeed));
os << filenamePrefix << uniqueID;
filenamePrefix = os.str();
smallFilename = filenamePrefix + "-small";
largeFilename = filenamePrefix + "-large";
// FIXME(MCOL-5597):Tuning issue: with the defaults, each 100MB bucket would split s.t.
// the children could store another 4GB total.
// Given a good hash and evenly distributed data,
// the first level of expansion would happen for all JPs at once, giving a total
// capacity of (4GB * 40) = 160GB, when actual usage at that point is a little over 4GB.
// Instead, each will double in size, giving a capacity of 8GB -> 16 -> 32, and so on.
bucketCount = 2;
smallSizeOnDisk = largeSizeOnDisk = 0;
buffer.reinit(smallRG);
smallRG.setData(&buffer);
smallRG.resetRowGroup(0);
smallRG.getRow(0, &smallRow);
compressor = jp.compressor;
}
JoinPartition::~JoinPartition()
{
if (fileMode)
{
smallFile.close();
largeFile.close();
boost::filesystem::remove(smallFilename);
boost::filesystem::remove(largeFilename);
}
}
int64_t JoinPartition::insertSmallSideRGData(RGData& rgData)
{
int64_t ret;
ret = processSmallBuffer(rgData);
return ret;
}
int64_t JoinPartition::insertSmallSideRGData(vector<RGData>& rgData)
{
int64_t ret = 0;
// this iterates over the vector backward to free mem asap
while (rgData.size() > 0)
{
ret += insertSmallSideRGData(rgData.back());
rgData.pop_back();
}
return ret;
}
int64_t JoinPartition::insertSmallSideRow(const Row& row)
{
int64_t ret = 0;
copyRow(row, &smallRow);
smallRG.incRowCount();
if (smallRG.getRowCount() == 8192)
ret = processSmallBuffer();
else
smallRow.nextRow();
return ret;
}
int64_t JoinPartition::insertLargeSideRGData(RGData& rgData)
{
int64_t ret;
ret = processLargeBuffer(rgData);
return ret;
}
int64_t JoinPartition::insertLargeSideRow(const Row& row)
{
int64_t ret = 0;
copyRow(row, &largeRow);
largeRG.incRowCount();
if (largeRG.getRowCount() == 8192)
ret = processLargeBuffer();
else
largeRow.nextRow();
return ret;
}
int64_t JoinPartition::doneInsertingSmallData()
{
/*
flush buffers to leaf nodes
config for large-side insertion
*/
int64_t ret = 0;
int64_t leafNodeIncrement;
/* flushing doesn't apply to the root node b/c it inserts entire RGs at once */
if (!rootNode)
ret = processSmallBuffer();
if (!fileMode)
for (int i = 0; i < (int)buckets.size(); i++)
{
leafNodeIncrement = buckets[i]->doneInsertingSmallData();
ret += leafNodeIncrement;
smallSizeOnDisk += leafNodeIncrement;
}
if (!rootNode)
{
buffer.reinit(largeRG);
largeRG.setData(&buffer);
largeRG.resetRowGroup(0);
largeRG.getRow(0, &largeRow);
}
if (maxSmallSize < smallSizeOnDisk)
maxSmallSize = smallSizeOnDisk;
return ret;
}
int64_t JoinPartition::doneInsertingLargeData()
{
/*
flush buffers to leaf nodes
*/
int64_t ret = 0;
int64_t leafNodeIncrement;
/* flushing doesn't apply to the root node b/c it inserts entire RGs at once */
if (!rootNode)
ret = processLargeBuffer();
if (!fileMode)
for (int i = 0; i < (int)buckets.size(); i++)
{
leafNodeIncrement = buckets[i]->doneInsertingLargeData();
ret += leafNodeIncrement;
largeSizeOnDisk += leafNodeIncrement;
}
if (maxLargeSize < largeSizeOnDisk)
maxLargeSize = largeSizeOnDisk;
return ret;
}
bool JoinPartition::canConvertToSplitMode()
{
// TODO: Make depth configurable.
if (!canSplit || currentPartitionTreeDepth >= maxPartitionTreeDepth)
return false;
ByteStream bs;
RowGroup& rg = smallRG;
Row& row = smallRow;
RGData rgData;
uint64_t totalRowCount = 0;
std::unordered_map<uint32_t, uint32_t> rowDist;
nextSmallOffset = 0;
while (1)
{
uint32_t hash;
readByteStream(0, &bs);
if (bs.length() == 0)
break;
rgData.deserialize(bs);
rg.setData(&rgData);
for (uint32_t j = 0, e = rg.getRowCount(); j < e; ++j)
{
rg.getRow(j, &row);
if (antiWithMatchNulls && hasNullJoinColumn(row))
continue;
uint64_t tmp;
if (typelessJoin)
hash = getHashOfTypelessKey(row, smallKeyCols, hashSeed) % bucketCount;
else
{
if (UNLIKELY(row.isUnsigned(smallKeyCols[0])))
tmp = row.getUintField(smallKeyCols[0]);
else
tmp = row.getIntField(smallKeyCols[0]);
hash = hasher((char*)&tmp, 8, hashSeed);
hash = hasher.finalize(hash, 8) % bucketCount;
}
totalRowCount++;
rowDist[hash]++;
}
}
for (const auto& [hash, currentRowCount] : rowDist)
{
if (currentRowCount == totalRowCount)
{
canSplit = false;
break;
}
}
rg.setData(&buffer);
rg.resetRowGroup(0);
rg.getRow(0, &row);
return canSplit;
}
int64_t JoinPartition::convertToSplitMode()
{
#ifdef DEBUG_DJS
cout << "Convert to split mode " << endl;
#endif
ByteStream bs;
RGData rgData;
uint32_t hash;
uint64_t tmp;
int64_t ret = -(int64_t)smallSizeOnDisk; // smallFile gets deleted
fileMode = false;
htSizeEstimate = 0;
smallSizeOnDisk = 0;
buckets.reserve(bucketCount);
for (uint32_t i = 0; i < bucketCount; i++)
buckets.push_back(
boost::shared_ptr<JoinPartition>(new JoinPartition(*this, false, currentPartitionTreeDepth + 1)));
RowGroup& rg = smallRG;
Row& row = smallRow;
nextSmallOffset = 0;
while (1)
{
readByteStream(0, &bs);
if (bs.length() == 0)
break;
rgData.deserialize(bs);
rg.setData(&rgData);
for (uint32_t j = 0; j < rg.getRowCount(); j++)
{
rg.getRow(j, &row);
if (antiWithMatchNulls && hasNullJoinColumn(row))
{
if (needsAllNullRows || !gotNullRow)
{
for (j = 0; j < bucketCount; j++)
ret += buckets[j]->insertSmallSideRow(row);
gotNullRow = true;
}
continue;
}
if (typelessJoin)
hash = getHashOfTypelessKey(row, smallKeyCols, hashSeed) % bucketCount;
else
{
if (UNLIKELY(row.isUnsigned(smallKeyCols[0])))
tmp = row.getUintField(smallKeyCols[0]);
else
tmp = row.getIntField(smallKeyCols[0]);
hash = hasher((char*)&tmp, 8, hashSeed);
hash = hasher.finalize(hash, 8) % bucketCount;
}
buckets[hash]->insertSmallSideRow(row);
}
}
boost::filesystem::remove(smallFilename);
smallFilename.clear();
rg.setData(&buffer);
rg.resetRowGroup(0);
rg.getRow(0, &row);
return ret;
}
/* either forwards the specified buffer to the next level of JP's or
writes it to a file, returns the # of bytes written to the file */
int64_t JoinPartition::processSmallBuffer()
{
int64_t ret;
ret = processSmallBuffer(buffer);
smallRG.resetRowGroup(0);
smallRG.getRow(0, &smallRow);
return ret;
}
int64_t JoinPartition::processSmallBuffer(RGData& rgData)
{
RowGroup& rg = smallRG;
Row& row = smallRow;
int64_t ret = 0;
rg.setData(&rgData);
if (fileMode)
{
ByteStream bs;
rg.serializeRGData(bs);
ret = writeByteStream(0, bs);
// FIXME(MCOL-5597): Properly calculate the size of the bucket.
htSizeEstimate += rg.getRowCount() * rg.getColumnCount();
// Check whether this partition is now too big -> convert to split mode.
if (htTargetSize < htSizeEstimate && canConvertToSplitMode())
ret += convertToSplitMode();
}
else
{
uint64_t hash, tmp;
int i, j;
for (i = 0; i < (int)rg.getRowCount(); i++)
{
rg.getRow(i, &row);
if (antiWithMatchNulls && hasNullJoinColumn(row))
{
if (needsAllNullRows || !gotNullRow)
{
for (j = 0; j < (int)bucketCount; j++)
ret += buckets[j]->insertSmallSideRow(row);
gotNullRow = true;
}
continue;
}
if (typelessJoin)
hash = getHashOfTypelessKey(row, smallKeyCols, hashSeed) % bucketCount;
else
{
if (UNLIKELY(row.isUnsigned(smallKeyCols[0])))
tmp = row.getUintField(smallKeyCols[0]);
else
tmp = row.getIntField(smallKeyCols[0]);
hash = hasher((char*)&tmp, 8, hashSeed);
hash = hasher.finalize(hash, 8) % bucketCount;
}
ret += buckets[hash]->insertSmallSideRow(row);
}
}
smallSizeOnDisk += ret;
return ret;
}
// the difference between processSmall & processLarge is mostly the names of
// variables being small* -> large*, template? */
int64_t JoinPartition::processLargeBuffer()
{
int64_t ret;
ret = processLargeBuffer(buffer);
largeRG.resetRowGroup(0);
largeRG.getRow(0, &largeRow);
return ret;
}
int64_t JoinPartition::processLargeBuffer(RGData& rgData)
{
RowGroup& rg = largeRG;
Row& row = largeRow;
int64_t ret = 0;
int i, j;
rg.setData(&rgData);
// Need to fail a query with an anti join, an FE filter, and a NULL row on the
// large side b/c it needs to be joined with the entire small side table.
if (antiWithMatchNulls && needsAllNullRows)
{
rg.getRow(0, &row);
for (i = 0; i < (int)rg.getRowCount(); i++, row.nextRow())
{
for (j = 0; j < (int)largeKeyCols.size(); j++)
{
if (row.isNullValue(largeKeyCols[j]))
throw QueryDataExcept("", ERR_DBJ_ANTI_NULL);
}
}
}
if (fileMode)
{
ByteStream bs;
rg.serializeRGData(bs);
ret = writeByteStream(1, bs);
}
else
{
uint64_t hash, tmp;
int i;
for (i = 0; i < (int)rg.getRowCount(); i++)
{
rg.getRow(i, &row);
if (typelessJoin)
hash = getHashOfTypelessKey(row, largeKeyCols, hashSeed) % bucketCount;
else
{
if (UNLIKELY(row.isUnsigned(largeKeyCols[0])))
tmp = row.getUintField(largeKeyCols[0]);
else
tmp = row.getIntField(largeKeyCols[0]);
hash = hasher((char*)&tmp, 8, hashSeed);
hash = hasher.finalize(hash, 8) % bucketCount;
}
ret += buckets[hash]->insertLargeSideRow(row);
}
}
largeSizeOnDisk += ret;
return ret;
}
void JoinPartition::collectJoinPartitions(std::vector<JoinPartition*>& joinPartitions)
{
if (fileMode)
{
joinPartitions.push_back(this);
return;
}
for (uint32_t currentBucket = 0; currentBucket < bucketCount; ++currentBucket)
{
buckets[currentBucket]->collectJoinPartitions(joinPartitions);
}
}
boost::shared_ptr<RGData> JoinPartition::getNextLargeRGData()
{
boost::shared_ptr<RGData> ret;
ByteStream bs;
readByteStream(1, &bs);
if (bs.length() != 0)
{
ret.reset(new RGData());
ret->deserialize(bs);
}
else
nextLargeOffset = 0;
return ret;
}
bool JoinPartition::hasNullJoinColumn(Row& r)
{
for (uint32_t i = 0; i < smallKeyCols.size(); i++)
{
if (r.isNullValue(smallKeyCols[i]))
return true;
}
return false;
}
void JoinPartition::initForProcessing()
{
int i;
nextPartitionToReturn = 0;
if (!fileMode)
for (i = 0; i < (int)bucketCount; i++)
buckets[i]->initForProcessing();
else
nextLargeOffset = 0;
}
void JoinPartition::initForLargeSideFeed()
{
int i;
if (!rootNode)
{
buffer.reinit(largeRG);
largeRG.setData(&buffer);
largeRG.resetRowGroup(0);
largeRG.getRow(0, &largeRow);
}
largeSizeOnDisk = 0;
if (fileMode)
nextLargeOffset = 0;
else
for (i = 0; i < (int)bucketCount; i++)
buckets[i]->initForLargeSideFeed();
}
void JoinPartition::saveSmallSidePartition(vector<RGData>& rgData)
{
htSizeEstimate = 0;
smallSizeOnDisk = 0;
nextSmallOffset = 0;
boost::filesystem::remove(smallFilename);
insertSmallSideRGData(rgData);
doneInsertingSmallData();
}
void JoinPartition::readByteStream(int which, ByteStream* bs)
{
size_t& offset = (which == 0 ? nextSmallOffset : nextLargeOffset);
fstream& fs = (which == 0 ? smallFile : largeFile);
const char* filename = (which == 0 ? smallFilename.c_str() : largeFilename.c_str());
size_t len;
bs->restart();
fs.open(filename, ios::binary | ios::in);
int saveErrno = errno;
if (!fs)
{
fs.close();
ostringstream os;
os << "Disk join could not open file (read access) " << filename << ": " << strerror(saveErrno) << endl;
throw IDBExcept(os.str().c_str(), ERR_DBJ_FILE_IO_ERROR);
}
fs.seekg(offset);
fs.read((char*)&len, sizeof(len));
saveErrno = errno;
if (!fs)
{
if (fs.eof())
{
fs.close();
return;
}
else
{
fs.close();
ostringstream os;
os << "Disk join could not read file " << filename << ": " << strerror(saveErrno) << endl;
throw IDBExcept(os.str().c_str(), ERR_DBJ_FILE_IO_ERROR);
}
}
idbassert(len != 0);
totalBytesRead += sizeof(len);
if (!useCompression)
{
bs->needAtLeast(len);
fs.read((char*)bs->getInputPtr(), len);
saveErrno = errno;
if (!fs)
{
fs.close();
ostringstream os;
os << "Disk join could not read file " << filename << ": " << strerror(saveErrno) << endl;
throw IDBExcept(os.str().c_str(), ERR_DBJ_FILE_IO_ERROR);
}
totalBytesRead += len;
bs->advanceInputPtr(len);
}
else
{
size_t uncompressedSize;
fs.read((char*)&uncompressedSize, sizeof(uncompressedSize));
boost::scoped_array<char> buf(new char[len]);
fs.read(buf.get(), len);
saveErrno = errno;
if (!fs || !uncompressedSize)
{
fs.close();
ostringstream os;
os << "Disk join could not read file " << filename << ": " << strerror(saveErrno) << endl;
throw IDBExcept(os.str().c_str(), ERR_DBJ_FILE_IO_ERROR);
}
totalBytesRead += len;
bs->needAtLeast(uncompressedSize);
compressor->uncompress(buf.get(), len, (char*)bs->getInputPtr(), &uncompressedSize);
bs->advanceInputPtr(uncompressedSize);
}
offset = fs.tellg();
fs.close();
}
uint64_t JoinPartition::writeByteStream(int which, ByteStream& bs)
{
size_t& offset = (which == 0 ? nextSmallOffset : nextLargeOffset);
fstream& fs = (which == 0 ? smallFile : largeFile);
const char* filename = (which == 0 ? smallFilename.c_str() : largeFilename.c_str());
fs.open(filename, ios::binary | ios::out | ios::app);
int saveErrno = errno;
if (!fs)
{
fs.close();
ostringstream os;
os << "Disk join could not open file (write access) " << filename << ": " << strerror(saveErrno) << endl;
throw IDBExcept(os.str().c_str(), ERR_DBJ_FILE_IO_ERROR);
}
uint64_t ret = 0;
BSSizeType len = bs.length();
idbassert(len != 0);
fs.seekp(offset);
if (!useCompression)
{
ret = len + sizeof(len);
fs.write((char*)&len, sizeof(len));
fs.write((char*)bs.buf(), len);
saveErrno = errno;
if (!fs)
{
fs.close();
ostringstream os;
os << "Disk join could not write file " << filename << ": " << strerror(saveErrno) << endl;
throw IDBExcept(os.str().c_str(), ERR_DBJ_FILE_IO_ERROR);
}
totalBytesWritten += sizeof(len) + len;
}
else
{
size_t maxSize = compressor->maxCompressedSize(len);
size_t actualSize = maxSize;
boost::scoped_array<uint8_t> compressed(new uint8_t[maxSize]);
compressor->compress((char*)bs.buf(), len, (char*)compressed.get(), &actualSize);
ret = actualSize + sizeof(len); // sizeof (size_t) == 8. Why 4?
fs.write((char*)&actualSize, sizeof(actualSize));
// Save uncompressed len.
fs.write((char*)&len, sizeof(len));
fs.write((char*)compressed.get(), actualSize);
saveErrno = errno;
if (!fs)
{
fs.close();
ostringstream os;
os << "Disk join could not write file " << filename << ": " << strerror(saveErrno) << endl;
throw IDBExcept(os.str().c_str(), ERR_DBJ_FILE_IO_ERROR);
}
totalBytesWritten += sizeof(len) + actualSize;
}
bs.advance(len);
offset = fs.tellp();
fs.close();
if (fs.fail())
{
ostringstream os;
os << "Disk join file " << filename << ": close() failure, probable exhaustion of disk space." << endl;
throw IDBExcept(os.str().c_str(), ERR_DBJ_FILE_IO_ERROR);
}
return ret;
}
uint64_t JoinPartition::getBytesRead()
{
uint64_t ret;
if (fileMode)
return totalBytesRead;
ret = totalBytesRead;
for (int i = 0; i < (int)bucketCount; i++)
ret += buckets[i]->getBytesRead();
return ret;
}
uint64_t JoinPartition::getBytesWritten()
{
uint64_t ret;
if (fileMode)
return totalBytesWritten;
ret = totalBytesWritten;
for (int i = 0; i < (int)bucketCount; i++)
ret += buckets[i]->getBytesWritten();
return ret;
}
} // namespace joiner