database/sqlite
1
0
Fork 0
mirror of https://github.com/sqlite/sqlite.git synced 2025-11-12 13:01:09 +03:00
Code Activity

Avoid storing redundant fields in sorter records when the sort-key

Browse Source 
and data have fields in common.

FossilOrigin-Name: b835cf3e507b910b6a3e0f802ce2c40a72d0c227
This commit is contained in:
drh
2016-11-11 19:08:00 +00:00
parent 4b727f17d6 04cd7aa373
commit 66adb0a848
5 changed files with 66 additions and 28 deletions
Download Patch File Download Diff File Expand all files Collapse all files

64
src/select.c
View File

@@ -521,7 +521,7 @@ static void pushOntoSorter(
int iLimit; /* LIMIT counter */
assert( bSeq==0 || bSeq==1 );
assert( nData==1 || regData==regOrigData );
assert( nData==1 || regData==regOrigData || regOrigData==0 );
if( nPrefixReg ){
assert( nPrefixReg==nExpr+bSeq );
regBase = regData - nExpr - bSeq;
@@ -533,11 +533,11 @@ static void pushOntoSorter(
iLimit = pSelect->iOffset ? pSelect->iOffset+1 : pSelect->iLimit;
pSort->labelDone = sqlite3VdbeMakeLabel(v);
sqlite3ExprCodeExprList(pParse, pSort->pOrderBy, regBase, regOrigData,
SQLITE_ECEL_DUP|SQLITE_ECEL_REF);
SQLITE_ECEL_DUP | (regOrigData? SQLITE_ECEL_REF : 0));
if( bSeq ){
sqlite3VdbeAddOp2(v, OP_Sequence, pSort->iECursor, regBase+nExpr);
}
if( nPrefixReg==0 ){
if( nPrefixReg==0 && nData>0 ){
sqlite3ExprCodeMove(pParse, regData, regBase+nExpr+bSeq, nData);
}
sqlite3VdbeAddOp3(v, OP_MakeRecord, regBase+nOBSat, nBase-nOBSat, regRecord);
@@ -667,7 +667,7 @@ static void codeDistinct(
** If srcTab is negative, then the pEList expressions
** are evaluated in order to get the data for this row. If srcTab is
** zero or more, then data is pulled from srcTab and pEList is used only
** to get number columns and the datatype for each column.
** to get the number of columns and the collation sequence for each column.
*/
static void selectInnerLoop(
Parse *pParse, /* The parser context */
@@ -682,13 +682,20 @@ static void selectInnerLoop(
){
Vdbe *v = pParse->pVdbe;
int i;
int hasDistinct; /* True if the DISTINCT keyword is present */
int regResult; /* Start of memory holding result set */
int hasDistinct; /* True if the DISTINCT keyword is present */
int eDest = pDest->eDest; /* How to dispose of results */
int iParm = pDest->iSDParm; /* First argument to disposal method */
int nResultCol; /* Number of result columns */
int nPrefixReg = 0; /* Number of extra registers before regResult */
/* Usually, regResult is the first cell in an array of memory cells
** containing the current result row. In this case regOrig is set to the
** same value. However, if the results are being sent to the sorter, the
** values for any expressions that are also part of the sort-key are omitted
** from this array. In this case regOrig is set to zero. */
int regResult; /* Start of memory holding current results */
int regOrig; /* Start of memory holding full result (or 0) */
assert( v );
assert( pEList!=0 );
hasDistinct = pDistinct ? pDistinct->eTnctType : WHERE_DISTINCT_NOOP;
@@ -719,7 +726,7 @@ static void selectInnerLoop(
pParse->nMem += nResultCol;
}
pDest->nSdst = nResultCol;
regResult = pDest->iSdst;
regOrig = regResult = pDest->iSdst;
if( srcTab>=0 ){
for(i=0; i<nResultCol; i++){
sqlite3VdbeAddOp3(v, OP_Column, srcTab, i, regResult+i);
@@ -735,7 +742,26 @@ static void selectInnerLoop(
}else{
ecelFlags = 0;
}
sqlite3ExprCodeExprList(pParse, pEList, regResult, 0, ecelFlags);
assert( eDest!=SRT_Table || pSort==0 );
if( pSort && hasDistinct==0 && eDest!=SRT_EphemTab ){
/* For each expression in pEList that is a copy of an expression in
** the ORDER BY clause (pSort->pOrderBy), set the associated
** iOrderByCol value to one more than the index of the ORDER BY
** expression within the sort-key that pushOntoSorter() will generate.
** This allows the pEList field to be omitted from the sorted record,
** saving space and CPU cycles. */
ecelFlags |= (SQLITE_ECEL_OMITREF|SQLITE_ECEL_REF);
for(i=pSort->nOBSat; i<pSort->pOrderBy->nExpr; i++){
int j;
if( (j = pSort->pOrderBy->a[i].u.x.iOrderByCol)>0 ){
pEList->a[j-1].u.x.iOrderByCol = i+1-pSort->nOBSat;
}
}
regOrig = 0;
assert( eDest==SRT_Set || eDest==SRT_Mem
|| eDest==SRT_Coroutine || eDest==SRT_Output );
}
nResultCol = sqlite3ExprCodeExprList(pParse,pEList,regResult,0,ecelFlags);
}
/* If the DISTINCT keyword was present on the SELECT statement
@@ -875,7 +901,7 @@ static void selectInnerLoop(
** does not matter. But there might be a LIMIT clause, in which
** case the order does matter */
pushOntoSorter(
pParse, pSort, p, regResult, regResult, nResultCol, nPrefixReg);
pParse, pSort, p, regResult, regOrig, nResultCol, nPrefixReg);
}else{
int r1 = sqlite3GetTempReg(pParse);
assert( sqlite3Strlen30(pDest->zAffSdst)==nResultCol );
@@ -901,11 +927,12 @@ static void selectInnerLoop(
** memory cells and break out of the scan loop.
*/
case SRT_Mem: {
assert( nResultCol==pDest->nSdst );
if( pSort ){
assert( nResultCol<=pDest->nSdst );
pushOntoSorter(
pParse, pSort, p, regResult, regResult, nResultCol, nPrefixReg);
pParse, pSort, p, regResult, regOrig, nResultCol, nPrefixReg);
}else{
assert( nResultCol==pDest->nSdst );
assert( regResult==iParm );
/* The LIMIT clause will jump out of the loop for us */
}
@@ -918,7 +945,7 @@ static void selectInnerLoop(
testcase( eDest==SRT_Coroutine );
testcase( eDest==SRT_Output );
if( pSort ){
pushOntoSorter(pParse, pSort, p, regResult, regResult, nResultCol,
pushOntoSorter(pParse, pSort, p, regResult, regOrig, nResultCol,
nPrefixReg);
}else if( eDest==SRT_Coroutine ){
sqlite3VdbeAddOp1(v, OP_Yield, pDest->iSDParm);
@@ -1203,14 +1230,13 @@ static void generateSortTail(
int iParm = pDest->iSDParm;
int regRow;
int regRowid;
int iCol;
int nKey;
int iSortTab; /* Sorter cursor to read from */
int nSortData; /* Trailing values to read from sorter */
int i;
int bSeq; /* True if sorter record includes seq. no. */
#ifdef SQLITE_ENABLE_EXPLAIN_COMMENTS
struct ExprList_item *aOutEx = p->pEList->a;
#endif
assert( addrBreak<0 );
if( pSort->labelBkOut ){
@@ -1248,8 +1274,14 @@ static void generateSortTail(
iSortTab = iTab;
bSeq = 1;
}
for(i=0; i<nSortData; i++){
sqlite3VdbeAddOp3(v, OP_Column, iSortTab, nKey+bSeq+i, regRow+i);
for(i=0, iCol=nKey+bSeq; i<nSortData; i++){
int iRead;
if( aOutEx[i].u.x.iOrderByCol ){
iRead = aOutEx[i].u.x.iOrderByCol-1;
}else{
iRead = iCol++;
}
sqlite3VdbeAddOp3(v, OP_Column, iSortTab, iRead, regRow+i);
VdbeComment((v, "%s", aOutEx[i].zName ? aOutEx[i].zName : aOutEx[i].zSpan));
}
switch( eDest ){