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Defer loading result column values into registers on an ORDER BY LIMIT until

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we know that the LIMIT does not exclude the current row.

FossilOrigin-Name: ce4ef46058f4aaea6623a41255a2e4b69bb24f16a287391df48f6bacdb4c4989
This commit is contained in:
drh
2018-04-30 19:32:49 +00:00
parent b57e3ec5d8
commit bbd4ae5a2f
4 changed files with 139 additions and 36 deletions
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17
manifest
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@@ -1,5 +1,5 @@
C Test\scases\sadded\sfor\sSQLITE_DBCONFIG_RESET_DATABASE.
D 2018-04-28T19:08:02.897
C Defer\sloading\sresult\scolumn\svalues\sinto\sregisters\son\san\sORDER\sBY\sLIMIT\suntil\nwe\sknow\sthat\sthe\sLIMIT\sdoes\snot\sexclude\sthe\scurrent\srow.
D 2018-04-30T19:32:49.040
F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
F Makefile.in 5ce9343cba9c189046f1afe6d2bcc1f68079439febc05267b98aec6ecc752439
@@ -493,12 +493,12 @@ F src/printf.c d3b7844ddeb11fbbdd38dd84d09c9c1ac171d21fb038473c3aa97981201cc660
F src/random.c 80f5d666f23feb3e6665a6ce04c7197212a88384
F src/resolve.c 6415381a0e9d22c0e7cba33ca4a53f81474190862f5d4838190f5eb5b0b47bc9
F src/rowset.c 7b7e7e479212e65b723bf40128c7b36dc5afdfac
F src/select.c daf07d8defce3311f9e69f1280a874d78bc1d16c305f6aa689640f7afa02842f
F src/select.c 170834c5b9710676b192fc9b0fe0cf7970250b1a72b396435deb923f3670a58f
F src/shell.c.in 54b902ab7d840f60ddfabc13124c85d4980342c88aff7679f2cc25f67c21ade7
F src/sqlite.h.in d669de545f18f2f01362de02e309cd7f15185958c71bac8f53cd5438b46d2bea
F src/sqlite3.rc 5121c9e10c3964d5755191c80dd1180c122fc3a8
F src/sqlite3ext.h 83a3c4ce93d650bedfd1aa558cb85a516bd6d094445ee989740827d0d944368d
F src/sqliteInt.h 8ac0138eae10337b745b03dad0124fd63ae911c0503e795729503e7fc6234d57
F src/sqliteInt.h 3e354edb3090e31b51593e21ae54c541330987cfd87d69d86adf6e4d186408ca
F src/sqliteLimit.h 1513bfb7b20378aa0041e7022d04acb73525de35b80b252f1b83fedb4de6a76b
F src/status.c 46e7aec11f79dad50965a5ca5fa9de009f7d6bde08be2156f1538a0a296d4d0e
F src/table.c b46ad567748f24a326d9de40e5b9659f96ffff34
@@ -1727,7 +1727,10 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
P 564ae8297d417ba4b7978e430d41f125007177673163f6ed9adc3a3974f73d24
R f62951ddf79b7c70897c7cedc3fc5902
P 08665a9e2e50a0a1e62529884cf65f8090debe89a306a3904b53268729ab5ad5
R 4667c6ddbdfa5ae61d508da23236434a
T *branch * faster-order-by-limit
T *sym-faster-order-by-limit *
T -sym-trunk *
U drh
Z d48406f4893f856e5db8717a8971e33f
Z 8bfebc9ee79b135d90912539998ba9b3

2
manifest.uuid
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@@ -1 +1 @@
08665a9e2e50a0a1e62529884cf65f8090debe89a306a3904b53268729ab5ad5
ce4ef46058f4aaea6623a41255a2e4b69bb24f16a287391df48f6bacdb4c4989

147
src/select.c
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@@ -78,6 +78,7 @@ struct SortCtx {
int nKey; /* Number of PK columns for table pTab (>=1) */
} aDefer[4];
#endif
struct RowLoadInfo *pDeferredRowLoad; /* Deferred row loading info or NULL */
};
#define SORTFLAG_UseSorter 0x01 /* Use SorterOpen instead of OpenEphemeral */
@@ -536,6 +537,62 @@ static KeyInfo *keyInfoFromExprList(
int nExtra /* Add this many extra columns to the end */
);
/*
** An instance of this object holds information (beyond pParse and pSelect)
** needed to load the next result row that is to be added to the sorter.
*/
typedef struct RowLoadInfo RowLoadInfo;
struct RowLoadInfo {
int regResult; /* Store results in array of registers here */
u8 ecelFlags; /* Flag argument to ExprCodeExprList() */
#ifdef SQLITE_ENABLE_SORTER_REFERENCES
ExprList *pExtra; /* Extra columns needed by sorter refs */
int regExtraResult; /* Where to load the extra columns */
#endif
};
/*
** This routine does the work of loading query data into an array of
** registers so that it can be added to the sorter.
*/
static void innerLoopLoadRow(
Parse *pParse, /* Statement under construction */
Select *pSelect, /* The query being coded */
RowLoadInfo *pInfo /* Info needed to complete the row load */
){
sqlite3ExprCodeExprList(pParse, pSelect->pEList, pInfo->regResult,
0, pInfo->ecelFlags);
#ifdef SQLITE_ENABLE_SORTER_REFERENCES
if( pInfo->pExtra ){
sqlite3ExprCodeExprList(pParse, pInfo->pExtra, pInfo->regExtraResult, 0, 0);
sqlite3ExprListDelete(pParse->db, pInfo->pExtra);
}
#endif
}
/*
** Code the OP_MakeRecord instruction that generates the entry to be
** added into the sorter.
**
** Return the register in which the result is stored.
*/
static int makeSorterRecord(
Parse *pParse,
SortCtx *pSort,
Select *pSelect,
int regBase,
int nBase
){
int nOBSat = pSort->nOBSat;
Vdbe *v = pParse->pVdbe;
int regOut = ++pParse->nMem;
if( pSort->pDeferredRowLoad ){
innerLoopLoadRow(pParse, pSelect, pSort->pDeferredRowLoad);
}
sqlite3VdbeAddOp3(v, OP_MakeRecord, regBase+nOBSat, nBase-nOBSat, regOut);
return regOut;
}
/*
** Generate code that will push the record in registers regData
** through regData+nData-1 onto the sorter.
@@ -546,7 +603,7 @@ static void pushOntoSorter(
Select *pSelect, /* The whole SELECT statement */
int regData, /* First register holding data to be sorted */
int regOrigData, /* First register holding data before packing */
int nData, /* Number of elements in the data array */
int nData, /* Number of elements in the regData data array */
int nPrefixReg /* No. of reg prior to regData available for use */
){
Vdbe *v = pParse->pVdbe; /* Stmt under construction */
@@ -554,16 +611,31 @@ static void pushOntoSorter(
int nExpr = pSort->pOrderBy->nExpr; /* No. of ORDER BY terms */
int nBase = nExpr + bSeq + nData; /* Fields in sorter record */
int regBase; /* Regs for sorter record */
int regRecord = ++pParse->nMem; /* Assembled sorter record */
int regRecord = 0; /* Assembled sorter record */
int nOBSat = pSort->nOBSat; /* ORDER BY terms to skip */
int op; /* Opcode to add sorter record to sorter */
int iLimit; /* LIMIT counter */
int iSkip = 0; /* End of the sorter insert loop */
assert( bSeq==0 || bSeq==1 );
/* Three cases:
** (1) The data to be sorted has already been packed into a Record
** by a prior OP_MakeRecord. In this case nData==1 and regData
** will be completely unrelated to regOrigData.
** (2) All output columns are included in the sort record. In that
** case regData==regOrigData.
** (3) Some output columns are omitted from the sort record due to
** the SQLITE_ENABLE_SORTER_REFERENCE optimization, or due to the
** SQLITE_ECEL_OMITREF optimization. In that case, regOrigData==0
** to prevent this routine from trying to copy values that might
** not exist.
*/
assert( nData==1 || regData==regOrigData || regOrigData==0 );
if( nPrefixReg ){
assert( nPrefixReg==nExpr+bSeq );
regBase = regData - nExpr - bSeq;
regBase = regData - nPrefixReg;
}else{
regBase = pParse->nMem + 1;
pParse->nMem += nBase;
@@ -587,7 +659,7 @@ static void pushOntoSorter(
int nKey; /* Number of sorting key columns, including OP_Sequence */
KeyInfo *pKI; /* Original KeyInfo on the sorter table */
sqlite3VdbeAddOp3(v, OP_MakeRecord, regBase+nOBSat, nBase-nOBSat,regRecord);
regRecord = makeSorterRecord(pParse, pSort, pSelect, regBase, nBase);
regPrevKey = pParse->nMem+1;
pParse->nMem += pSort->nOBSat;
nKey = nExpr - pSort->nOBSat + bSeq;
@@ -638,17 +710,16 @@ static void pushOntoSorter(
** of the outer loop.
*/
int iCsr = pSort->iECursor;
int iJmp = sqlite3VdbeCurrentAddr(v)+5+(nOBSat<=0)+pSort->bOrderedInnerLoop;
assert( pSort->bOrderedInnerLoop==0 || pSort->bOrderedInnerLoop==1 );
sqlite3VdbeAddOp2(v, OP_IfNotZero, iLimit, sqlite3VdbeCurrentAddr(v)+4);
VdbeCoverage(v);
sqlite3VdbeAddOp2(v, OP_Last, iCsr, 0);
sqlite3VdbeAddOp4Int(v, OP_IdxLE, iCsr, iJmp, regBase+nOBSat, nExpr-nOBSat);
iSkip = sqlite3VdbeAddOp4Int(v, OP_IdxLE,
iCsr, 0, regBase+nOBSat, nExpr-nOBSat);
VdbeCoverage(v);
sqlite3VdbeAddOp1(v, OP_Delete, iCsr);
}
if( nOBSat<=0 ){
sqlite3VdbeAddOp3(v, OP_MakeRecord, regBase+nOBSat, nBase-nOBSat,regRecord);
if( regRecord==0 ){
regRecord = makeSorterRecord(pParse, pSort, pSelect, regBase, nBase);
}
if( pSort->sortFlags & SORTFLAG_UseSorter ){
op = OP_SorterInsert;
@@ -657,6 +728,11 @@ static void pushOntoSorter(
}
sqlite3VdbeAddOp4Int(v, op, pSort->iECursor, regRecord,
regBase+nOBSat, nBase-nOBSat);
if( iSkip ){
assert( pSort->bOrderedInnerLoop==0 || pSort->bOrderedInnerLoop==1 );
sqlite3VdbeChangeP2(v, iSkip,
sqlite3VdbeCurrentAddr(v) + pSort->bOrderedInnerLoop);
}
}
/*
@@ -742,9 +818,6 @@ static void selectExprDefer(
Table *pTab = pExpr->pTab;
if( pExpr->op==TK_COLUMN && pTab && !IsVirtual(pTab)
&& (pTab->aCol[pExpr->iColumn].colFlags & COLFLAG_SORTERREF)
#if 0
&& pTab->pSchema && pTab->pSelect==0 && !IsVirtual(pTab)
#endif
){
int j;
for(j=0; j<nDefer; j++){
@@ -811,6 +884,7 @@ static void selectInnerLoop(
int iParm = pDest->iSDParm; /* First argument to disposal method */
int nResultCol; /* Number of result columns */
int nPrefixReg = 0; /* Number of extra registers before regResult */
RowLoadInfo sRowLoadInfo; /* Info for deferred row loading */
/* 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
@@ -863,7 +937,8 @@ static void selectInnerLoop(
/* If the destination is an EXISTS(...) expression, the actual
** values returned by the SELECT are not required.
*/
u8 ecelFlags;
u8 ecelFlags; /* "ecel" is an abbreviation of "ExprCodeExprList" */
ExprList *pEList;
if( eDest==SRT_Mem || eDest==SRT_Output || eDest==SRT_Coroutine ){
ecelFlags = SQLITE_ECEL_DUP;
}else{
@@ -877,6 +952,7 @@ static void selectInnerLoop(
** This allows the p->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 ){
@@ -897,20 +973,46 @@ static void selectInnerLoop(
pParse->nMem += pExtra->nExpr;
}
#endif
/* Adjust nResultCol to account for columns that are omitted
** from the sorter by the optimizations in this branch */
pEList = p->pEList;
for(i=0; i<pEList->nExpr; i++){
if( pEList->a[i].u.x.iOrderByCol>0
#ifdef SQLITE_ENABLE_SORTER_REFERENCES
|| pEList->a[i].bSorterRef
#endif
){
nResultCol--;
regOrig = 0;
}
}
testcase( regOrig );
testcase( eDest==SRT_Set );
testcase( eDest==SRT_Mem );
testcase( eDest==SRT_Coroutine );
testcase( eDest==SRT_Output );
assert( eDest==SRT_Set || eDest==SRT_Mem
|| eDest==SRT_Coroutine || eDest==SRT_Output );
}
nResultCol = sqlite3ExprCodeExprList(pParse,p->pEList,regResult,
0,ecelFlags);
sRowLoadInfo.regResult = regResult;
sRowLoadInfo.ecelFlags = ecelFlags;
#ifdef SQLITE_ENABLE_SORTER_REFERENCES
if( pExtra ){
nResultCol += sqlite3ExprCodeExprList(
pParse, pExtra, regResult + nResultCol, 0, 0
);
sqlite3ExprListDelete(pParse->db, pExtra);
}
sRowLoadInfo.pExtra = pExtra;
sRowLoadInfo.regExtraResult = regResult + nResultCol;
if( pExtra ) nResultCol += pExtra->nExpr;
#endif
if( p->iLimit
&& (ecelFlags & SQLITE_ECEL_OMITREF)!=0
&& nPrefixReg>0
){
assert( pSort!=0 );
assert( hasDistinct==0 );
pSort->pDeferredRowLoad = &sRowLoadInfo;
}else{
innerLoopLoadRow(pParse, p, &sRowLoadInfo);
}
}
/* If the DISTINCT keyword was present on the SELECT statement
@@ -1026,7 +1128,8 @@ static void selectInnerLoop(
}
#endif
if( pSort ){
pushOntoSorter(pParse, pSort, p, r1+nPrefixReg,regResult,1,nPrefixReg);
assert( regResult==regOrig );
pushOntoSorter(pParse, pSort, p, r1+nPrefixReg, regOrig, 1, nPrefixReg);
}else{
int r2 = sqlite3GetTempReg(pParse);
sqlite3VdbeAddOp2(v, OP_NewRowid, iParm, r2);

7
src/sqliteInt.h
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@@ -2759,11 +2759,8 @@ struct Upsert {
** An instance of the following structure contains all information
** needed to generate code for a single SELECT statement.
**
** nLimit is set to -1 if there is no LIMIT clause. nOffset is set to 0.
** If there is a LIMIT clause, the parser sets nLimit to the value of the
** limit and nOffset to the value of the offset (or 0 if there is not
** offset). But later on, nLimit and nOffset become the memory locations
** in the VDBE that record the limit and offset counters.
** See the header comment on the computeLimitRegisters() routine for a
** detailed description of the meaning of the iLimit and iOffset fields.
**
** addrOpenEphm[] entries contain the address of OP_OpenEphemeral opcodes.
** These addresses must be stored so that we can go back and fill in