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Merge the sorter-coalesce-writes branch into the trunk. This improves CREATE INDEX performance on some platforms.

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FossilOrigin-Name: e1e9cb08b011e67b767091e42225f22ec862fa64
This commit is contained in:
dan
2012-08-06 19:28:20 +00:00
parent e2e2ab3a2d 243be2b0e1
commit 09ac7ec544
12 changed files with 420 additions and 142 deletions
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408
src/vdbesort.c
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@@ -22,6 +22,7 @@
typedef struct VdbeSorterIter VdbeSorterIter;
typedef struct SorterRecord SorterRecord;
typedef struct FileWriter FileWriter;
/*
** NOTES ON DATA STRUCTURE USED FOR N-WAY MERGES:
@@ -119,6 +120,22 @@ struct VdbeSorterIter {
sqlite3_file *pFile; /* File iterator is reading from */
u8 *aAlloc; /* Allocated space */
u8 *aKey; /* Pointer to current key */
u8 *aBuffer; /* Current read buffer */
int nBuffer; /* Size of read buffer in bytes */
};
/*
** An instance of this structure is used to separate the stream of records
** being written to files by the merge-sort code into aligned, page-sized
** blocks.
*/
struct FileWriter {
u8 *aBuffer; /* Pointer to write buffer */
int nBuffer; /* Size of write buffer in bytes */
int iBufStart; /* First byte of buffer to write */
int iBufEnd; /* Last byte of buffer to write */
i64 iWriteOff; /* Offset of start of buffer in file */
sqlite3_file *pFile; /* File to write to */
};
/*
@@ -144,9 +161,125 @@ struct SorterRecord {
*/
static void vdbeSorterIterZero(sqlite3 *db, VdbeSorterIter *pIter){
sqlite3DbFree(db, pIter->aAlloc);
sqlite3DbFree(db, pIter->aBuffer);
memset(pIter, 0, sizeof(VdbeSorterIter));
}
/*
** Read nByte bytes of data from the stream of data iterated by object p.
** If successful, set *ppOut to point to a buffer containing the data
** and return SQLITE_OK. Otherwise, if an error occurs, return an SQLite
** error code.
**
** The buffer indicated by *ppOut may only be considered valid until the
** next call to this function.
*/
static int vdbeSorterIterRead(
sqlite3 *db, /* Database handle (for malloc) */
VdbeSorterIter *p, /* Iterator */
int nByte, /* Bytes of data to read */
u8 **ppOut /* OUT: Pointer to buffer containing data */
){
int iBuf; /* Offset within buffer to read from */
int nAvail; /* Bytes of data available in buffer */
assert( p->aBuffer );
/* If there is no more data to be read from the buffer, read the next
** p->nBuffer bytes of data from the file into it. Or, if there are less
** than p->nBuffer bytes remaining in the PMA, read all remaining data. */
iBuf = p->iReadOff % p->nBuffer;
if( iBuf==0 ){
int nRead; /* Bytes to read from disk */
int rc; /* sqlite3OsRead() return code */
/* Determine how many bytes of data to read. */
nRead = p->iEof - p->iReadOff;
if( nRead>p->nBuffer ) nRead = p->nBuffer;
assert( nRead>0 );
/* Read data from the file. Return early if an error occurs. */
rc = sqlite3OsRead(p->pFile, p->aBuffer, nRead, p->iReadOff);
assert( rc!=SQLITE_IOERR_SHORT_READ );
if( rc!=SQLITE_OK ) return rc;
}
nAvail = p->nBuffer - iBuf;
if( nByte<=nAvail ){
/* The requested data is available in the in-memory buffer. In this
** case there is no need to make a copy of the data, just return a
** pointer into the buffer to the caller. */
*ppOut = &p->aBuffer[iBuf];
p->iReadOff += nByte;
}else{
/* The requested data is not all available in the in-memory buffer.
** In this case, allocate space at p->aAlloc[] to copy the requested
** range into. Then return a copy of pointer p->aAlloc to the caller. */
int nRem; /* Bytes remaining to copy */
/* Extend the p->aAlloc[] allocation if required. */
if( p->nAlloc<nByte ){
int nNew = p->nAlloc*2;
while( nByte>nNew ) nNew = nNew*2;
p->aAlloc = sqlite3DbReallocOrFree(db, p->aAlloc, nNew);
if( !p->aAlloc ) return SQLITE_NOMEM;
p->nAlloc = nNew;
}
/* Copy as much data as is available in the buffer into the start of
** p->aAlloc[]. */
memcpy(p->aAlloc, &p->aBuffer[iBuf], nAvail);
p->iReadOff += nAvail;
nRem = nByte - nAvail;
/* The following loop copies up to p->nBuffer bytes per iteration into
** the p->aAlloc[] buffer. */
while( nRem>0 ){
int rc; /* vdbeSorterIterRead() return code */
int nCopy; /* Number of bytes to copy */
u8 *aNext; /* Pointer to buffer to copy data from */
nCopy = nRem;
if( nRem>p->nBuffer ) nCopy = p->nBuffer;
rc = vdbeSorterIterRead(db, p, nCopy, &aNext);
if( rc!=SQLITE_OK ) return rc;
assert( aNext!=p->aAlloc );
memcpy(&p->aAlloc[nByte - nRem], aNext, nCopy);
nRem -= nCopy;
}
*ppOut = p->aAlloc;
}
return SQLITE_OK;
}
/*
** Read a varint from the stream of data accessed by p. Set *pnOut to
** the value read.
*/
static int vdbeSorterIterVarint(sqlite3 *db, VdbeSorterIter *p, u64 *pnOut){
int iBuf;
iBuf = p->iReadOff % p->nBuffer;
if( iBuf && (p->nBuffer-iBuf)>=9 ){
p->iReadOff += sqlite3GetVarint(&p->aBuffer[iBuf], pnOut);
}else{
u8 aVarint[9];
int i;
for(i=0; i<sizeof(aVarint); i++){
u8 *a;
int rc = vdbeSorterIterRead(db, p, 1, &a);
if( rc ) return rc;
aVarint[i] = *a;
if( (aVarint[i] & 0x80)==0 ) break;
}
sqlite3GetVarint(aVarint, pnOut);
}
return SQLITE_OK;
}
/*
** Advance iterator pIter to the next key in its PMA. Return SQLITE_OK if
** no error occurs, or an SQLite error code if one does.
@@ -156,96 +289,18 @@ static int vdbeSorterIterNext(
VdbeSorterIter *pIter /* Iterator to advance */
){
int rc; /* Return Code */
int nRead; /* Number of bytes read */
int nRec = 0; /* Size of record in bytes */
int iOff = 0; /* Size of serialized size varint in bytes */
u64 nRec = 0; /* Size of record in bytes */
assert( pIter->iEof>=pIter->iReadOff );
if( pIter->iEof-pIter->iReadOff>5 ){
nRead = 5;
}else{
nRead = (int)(pIter->iEof - pIter->iReadOff);
}
if( nRead<=0 ){
if( pIter->iReadOff>=pIter->iEof ){
/* This is an EOF condition */
vdbeSorterIterZero(db, pIter);
return SQLITE_OK;
}
rc = sqlite3OsRead(pIter->pFile, pIter->aAlloc, nRead, pIter->iReadOff);
rc = vdbeSorterIterVarint(db, pIter, &nRec);
if( rc==SQLITE_OK ){
iOff = getVarint32(pIter->aAlloc, nRec);
if( (iOff+nRec)>nRead ){
int nRead2; /* Number of extra bytes to read */
if( (iOff+nRec)>pIter->nAlloc ){
int nNew = pIter->nAlloc*2;
while( (iOff+nRec)>nNew ) nNew = nNew*2;
pIter->aAlloc = sqlite3DbReallocOrFree(db, pIter->aAlloc, nNew);
if( !pIter->aAlloc ) return SQLITE_NOMEM;
pIter->nAlloc = nNew;
}
nRead2 = iOff + nRec - nRead;
rc = sqlite3OsRead(
pIter->pFile, &pIter->aAlloc[nRead], nRead2, pIter->iReadOff+nRead
);
}
}
assert( rc!=SQLITE_OK || nRec>0 );
pIter->iReadOff += iOff+nRec;
pIter->nKey = nRec;
pIter->aKey = &pIter->aAlloc[iOff];
return rc;
}
/*
** Write a single varint, value iVal, to file-descriptor pFile. Return
** SQLITE_OK if successful, or an SQLite error code if some error occurs.
**
** The value of *piOffset when this function is called is used as the byte
** offset in file pFile to write to. Before returning, *piOffset is
** incremented by the number of bytes written.
*/
static int vdbeSorterWriteVarint(
sqlite3_file *pFile, /* File to write to */
i64 iVal, /* Value to write as a varint */
i64 *piOffset /* IN/OUT: Write offset in file pFile */
){
u8 aVarint[9]; /* Buffer large enough for a varint */
int nVarint; /* Number of used bytes in varint */
int rc; /* Result of write() call */
nVarint = sqlite3PutVarint(aVarint, iVal);
rc = sqlite3OsWrite(pFile, aVarint, nVarint, *piOffset);
*piOffset += nVarint;
return rc;
}
/*
** Read a single varint from file-descriptor pFile. Return SQLITE_OK if
** successful, or an SQLite error code if some error occurs.
**
** The value of *piOffset when this function is called is used as the
** byte offset in file pFile from whence to read the varint. If successful
** (i.e. if no IO error occurs), then *piOffset is set to the offset of
** the first byte past the end of the varint before returning. *piVal is
** set to the integer value read. If an error occurs, the final values of
** both *piOffset and *piVal are undefined.
*/
static int vdbeSorterReadVarint(
sqlite3_file *pFile, /* File to read from */
i64 *piOffset, /* IN/OUT: Read offset in pFile */
i64 *piVal /* OUT: Value read from file */
){
u8 aVarint[9]; /* Buffer large enough for a varint */
i64 iOff = *piOffset; /* Offset in file to read from */
int rc; /* Return code */
rc = sqlite3OsRead(pFile, aVarint, 9, iOff);
if( rc==SQLITE_OK ){
*piOffset += getVarint(aVarint, (u64 *)piVal);
pIter->nKey = (int)nRec;
rc = vdbeSorterIterRead(db, pIter, nRec, &pIter->aKey);
}
return rc;
@@ -264,22 +319,47 @@ static int vdbeSorterIterInit(
VdbeSorterIter *pIter, /* Iterator to populate */
i64 *pnByte /* IN/OUT: Increment this value by PMA size */
){
int rc;
int rc = SQLITE_OK;
int nBuf;
nBuf = sqlite3BtreeGetPageSize(db->aDb[0].pBt);
assert( pSorter->iWriteOff>iStart );
assert( pIter->aAlloc==0 );
assert( pIter->aBuffer==0 );
pIter->pFile = pSorter->pTemp1;
pIter->iReadOff = iStart;
pIter->nAlloc = 128;
pIter->aAlloc = (u8 *)sqlite3DbMallocRaw(db, pIter->nAlloc);
if( !pIter->aAlloc ){
pIter->nBuffer = nBuf;
pIter->aBuffer = (u8 *)sqlite3DbMallocRaw(db, nBuf);
if( !pIter->aBuffer ){
rc = SQLITE_NOMEM;
}else{
i64 nByte; /* Total size of PMA in bytes */
rc = vdbeSorterReadVarint(pSorter->pTemp1, &pIter->iReadOff, &nByte);
*pnByte += nByte;
pIter->iEof = pIter->iReadOff + nByte;
int iBuf;
iBuf = iStart % nBuf;
if( iBuf ){
int nRead = nBuf - iBuf;
if( (iStart + nRead) > pSorter->iWriteOff ){
nRead = pSorter->iWriteOff - iStart;
}
rc = sqlite3OsRead(
pSorter->pTemp1, &pIter->aBuffer[iBuf], nRead, iStart
);
assert( rc!=SQLITE_IOERR_SHORT_READ );
}
if( rc==SQLITE_OK ){
u64 nByte; /* Size of PMA in bytes */
pIter->iEof = pSorter->iWriteOff;
rc = vdbeSorterIterVarint(db, pIter, &nByte);
pIter->iEof = pIter->iReadOff + nByte;
*pnByte += nByte;
}
}
if( rc==SQLITE_OK ){
rc = vdbeSorterIterNext(db, pIter);
}
@@ -531,6 +611,92 @@ static int vdbeSorterSort(const VdbeCursor *pCsr){
return SQLITE_OK;
}
/*
** Initialize a file-writer object.
*/
static int fileWriterInit(
sqlite3 *db, /* Database (for malloc) */
sqlite3_file *pFile, /* File to write to */
FileWriter *p, /* Object to populate */
i64 iStart /* Offset of pFile to begin writing at */
){
int nBuf = sqlite3BtreeGetPageSize(db->aDb[0].pBt);
memset(p, 0, sizeof(FileWriter));
p->aBuffer = (u8 *)sqlite3DbMallocRaw(db, nBuf);
if( !p->aBuffer ) return SQLITE_NOMEM;
p->iBufEnd = p->iBufStart = (iStart % nBuf);
p->iWriteOff = iStart - p->iBufStart;
p->nBuffer = nBuf;
p->pFile = pFile;
return SQLITE_OK;
}
/*
** Write nData bytes of data to the file-write object. Return SQLITE_OK
** if successful, or an SQLite error code if an error occurs.
*/
static int fileWriterWrite(FileWriter *p, u8 *pData, int nData){
int nRem = nData;
while( nRem>0 ){
int nCopy = nRem;
if( nCopy>(p->nBuffer - p->iBufEnd) ){
nCopy = p->nBuffer - p->iBufEnd;
}
memcpy(&p->aBuffer[p->iBufEnd], &pData[nData-nRem], nCopy);
p->iBufEnd += nCopy;
if( p->iBufEnd==p->nBuffer ){
int rc = sqlite3OsWrite(p->pFile,
&p->aBuffer[p->iBufStart], p->iBufEnd - p->iBufStart,
p->iWriteOff + p->iBufStart
);
if( rc!=SQLITE_OK ) return rc;
p->iBufStart = p->iBufEnd = 0;
p->iWriteOff += p->nBuffer;
}
assert( p->iBufEnd<p->nBuffer );
nRem -= nCopy;
}
return SQLITE_OK;
}
/*
** Flush any buffered data to disk and clean up the file-writer object.
** The results of using the file-writer after this call are undefined.
** Return SQLITE_OK if flushing the buffered data succeeds or is not
** required. Otherwise, return an SQLite error code.
**
** Before returning, set *piEof to the offset immediately following the
** last byte written to the file.
*/
static int fileWriterFinish(sqlite3 *db, FileWriter *p, i64 *piEof){
int rc = SQLITE_OK;
if( p->aBuffer && p->iBufEnd>p->iBufStart ){
rc = sqlite3OsWrite(p->pFile,
&p->aBuffer[p->iBufStart], p->iBufEnd - p->iBufStart,
p->iWriteOff + p->iBufStart
);
}
*piEof = (p->iWriteOff + p->iBufEnd);
sqlite3DbFree(db, p->aBuffer);
memset(p, 0, sizeof(FileWriter));
return rc;
}
/*
** Write value iVal encoded as a varint to the file-write object. Return
** SQLITE_OK if successful, or an SQLite error code if an error occurs.
*/
static int fileWriterWriteVarint(FileWriter *p, u64 iVal){
int nByte;
u8 aByte[10];
nByte = sqlite3PutVarint(aByte, iVal);
return fileWriterWrite(p, aByte, nByte);
}
/*
** Write the current contents of the in-memory linked-list to a PMA. Return
@@ -547,7 +713,11 @@ static int vdbeSorterSort(const VdbeCursor *pCsr){
*/
static int vdbeSorterListToPMA(sqlite3 *db, const VdbeCursor *pCsr){
int rc = SQLITE_OK; /* Return code */
int rc2; /* fileWriterFinish return code */
VdbeSorter *pSorter = pCsr->pSorter;
FileWriter writer;
memset(&writer, 0, sizeof(FileWriter));
if( pSorter->nInMemory==0 ){
assert( pSorter->pRecord==0 );
@@ -565,41 +735,32 @@ static int vdbeSorterListToPMA(sqlite3 *db, const VdbeCursor *pCsr){
}
if( rc==SQLITE_OK ){
i64 iOff = pSorter->iWriteOff;
rc = fileWriterInit(db, pSorter->pTemp1, &writer, pSorter->iWriteOff);
}
if( rc==SQLITE_OK ){
SorterRecord *p;
SorterRecord *pNext = 0;
static const char eightZeros[8] = { 0, 0, 0, 0, 0, 0, 0, 0 };
pSorter->nPMA++;
rc = vdbeSorterWriteVarint(pSorter->pTemp1, pSorter->nInMemory, &iOff);
rc = fileWriterWriteVarint(&writer, pSorter->nInMemory);
for(p=pSorter->pRecord; rc==SQLITE_OK && p; p=pNext){
pNext = p->pNext;
rc = vdbeSorterWriteVarint(pSorter->pTemp1, p->nVal, &iOff);
rc = fileWriterWriteVarint(&writer, p->nVal);
if( rc==SQLITE_OK ){
rc = sqlite3OsWrite(pSorter->pTemp1, p->pVal, p->nVal, iOff);
iOff += p->nVal;
rc = fileWriterWrite(&writer, p->pVal, p->nVal);
}
sqlite3DbFree(db, p);
}
/* This assert verifies that unless an error has occurred, the size of
** the PMA on disk is the same as the expected size stored in
** pSorter->nInMemory. */
assert( rc!=SQLITE_OK || pSorter->nInMemory==(
iOff-pSorter->iWriteOff-sqlite3VarintLen(pSorter->nInMemory)
));
pSorter->iWriteOff = iOff;
if( rc==SQLITE_OK ){
/* Terminate each file with 8 extra bytes so that from any offset
** in the file we can always read 9 bytes without a SHORT_READ error */
rc = sqlite3OsWrite(pSorter->pTemp1, eightZeros, 8, iOff);
}
pSorter->pRecord = p;
}
rc2 = fileWriterFinish(db, &writer, &pSorter->iWriteOff);
if( rc==SQLITE_OK ) rc = rc2;
return rc;
}
@@ -642,8 +803,14 @@ int sqlite3VdbeSorterWrite(
(pSorter->nInMemory>pSorter->mxPmaSize)
|| (pSorter->nInMemory>pSorter->mnPmaSize && sqlite3HeapNearlyFull())
)){
#ifdef SQLITE_DEBUG
i64 nExpect = pSorter->iWriteOff
+ sqlite3VarintLen(pSorter->nInMemory)
+ pSorter->nInMemory;
#endif
rc = vdbeSorterListToPMA(db, pCsr);
pSorter->nInMemory = 0;
assert( rc!=SQLITE_OK || (nExpect==pSorter->iWriteOff) );
}
return rc;
@@ -704,7 +871,7 @@ int sqlite3VdbeSorterRewind(sqlite3 *db, const VdbeCursor *pCsr, int *pbEof){
return vdbeSorterSort(pCsr);
}
/* Write the current b-tree to a PMA. Close the b-tree cursor. */
/* Write the current in-memory list to a PMA. */
rc = vdbeSorterListToPMA(db, pCsr);
if( rc!=SQLITE_OK ) return rc;
@@ -726,8 +893,12 @@ int sqlite3VdbeSorterRewind(sqlite3 *db, const VdbeCursor *pCsr, int *pbEof){
rc==SQLITE_OK && iNew*SORTER_MAX_MERGE_COUNT<pSorter->nPMA;
iNew++
){
int rc2; /* Return code from fileWriterFinish() */
FileWriter writer; /* Object used to write to disk */
i64 nWrite; /* Number of bytes in new PMA */
memset(&writer, 0, sizeof(FileWriter));
/* If there are SORTER_MAX_MERGE_COUNT or less PMAs in file pTemp1,
** initialize an iterator for each of them and break out of the loop.
** These iterators will be incrementally merged as the VDBE layer calls
@@ -750,23 +921,30 @@ int sqlite3VdbeSorterRewind(sqlite3 *db, const VdbeCursor *pCsr, int *pbEof){
}
if( rc==SQLITE_OK ){
rc = vdbeSorterWriteVarint(pTemp2, nWrite, &iWrite2);
rc = fileWriterInit(db, pTemp2, &writer, iWrite2);
}
if( rc==SQLITE_OK ){
rc = fileWriterWriteVarint(&writer, nWrite);
}
if( rc==SQLITE_OK ){
int bEof = 0;
while( rc==SQLITE_OK && bEof==0 ){
int nToWrite;
VdbeSorterIter *pIter = &pSorter->aIter[ pSorter->aTree[1] ];
assert( pIter->pFile );
nToWrite = pIter->nKey + sqlite3VarintLen(pIter->nKey);
rc = sqlite3OsWrite(pTemp2, pIter->aAlloc, nToWrite, iWrite2);
iWrite2 += nToWrite;
rc = fileWriterWriteVarint(&writer, pIter->nKey);
if( rc==SQLITE_OK ){
rc = fileWriterWrite(&writer, pIter->aKey, pIter->nKey);
}
if( rc==SQLITE_OK ){
rc = sqlite3VdbeSorterNext(db, pCsr, &bEof);
}
}
}
rc2 = fileWriterFinish(db, &writer, &iWrite2);
if( rc==SQLITE_OK ) rc = rc2;
}
if( pSorter->nPMA<=SORTER_MAX_MERGE_COUNT ){