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Reduce the size of the WhereScan object by 24 bytes while also clarifying its

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operation.

FossilOrigin-Name: cbc3c9a8bf169ae0b21f26855038502c6cc25cfe
This commit is contained in:
drh 2015-08-26 21:08:04 +00:00
parent 5579d59fb3
commit a3f108e93d
4 changed files with 32 additions and 33 deletions
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14
manifest
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@ -1,5 +1,5 @@
C Evaluate\sexpressions\sonly\sonce\swhen\sthe\ssame\sexpression\sis\sused\sin\sboth\sthe\nresult\sset\sand\sin\sthe\sORDER\sBY\sclause.
D 2015-08-26T14:01:41.658
C Reduce\sthe\ssize\sof\sthe\sWhereScan\sobject\sby\s24\sbytes\swhile\salso\sclarifying\sits\noperation.
D 2015-08-26T21:08:04.505
F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
F Makefile.in e2218eb228374422969de7b1680eda6864affcef
F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@ -414,8 +414,8 @@ F src/vxworks.h c18586c8edc1bddbc15c004fa16aeb1e1342b4fb
F src/wal.c 6fb6b68969e4692593c2552c4e7bff5882de2cb8
F src/wal.h df01efe09c5cb8c8e391ff1715cca294f89668a4
F src/walker.c 2e14d17f592d176b6dc879c33fbdec4fbccaa2ba
F src/where.c fb8546b8053433bfb39f6c39fdc99c111a6f97c5
F src/whereInt.h 880a8599226ac1c00203490d934f3ed79b292572
F src/where.c caabc9ec1e86168d7717833700cfed01a75f687a
F src/whereInt.h 901c17c1e3c82745ad9b85b4471543fa59c980e9
F src/wherecode.c 3d9113cc307ffeed58db41fe9f2d807c94787ab5
F src/whereexpr.c 1a308d1ee5144890d21ea9cf70d49bc96a83432b
F test/8_3_names.test ebbb5cd36741350040fd28b432ceadf495be25b2
@ -1380,7 +1380,7 @@ F tool/vdbe_profile.tcl 67746953071a9f8f2f668b73fe899074e2c6d8c1
F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
F tool/warnings.sh 48bd54594752d5be3337f12c72f28d2080cb630b
F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
P 58ba73630ecc4bc58b03a7962dd45b305ef605ef
R 657299463d01da646731fb6b8ab7d9fe
P c2f3bbad778504681b39ab9399a1eb3c1a35ab3f
R f5f6b9b31662d17ccccce315f9a81df1
U drh
Z 83e3936f8767c9500521d2082aa870a1
Z be2744e78cce20e5ac9fa855b3738fc2

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@ -1 +1 @@
c2f3bbad778504681b39ab9399a1eb3c1a35ab3f
cbc3c9a8bf169ae0b21f26855038502c6cc25cfe

46
src/where.c
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@ -171,37 +171,37 @@ static void createMask(WhereMaskSet *pMaskSet, int iCursor){
*/
static WhereTerm *whereScanNext(WhereScan *pScan){
int iCur; /* The cursor on the LHS of the term */
int iColumn; /* The column on the LHS of the term. -1 for IPK */
i16 iColumn; /* The column on the LHS of the term. -1 for IPK */
Expr *pX; /* An expression being tested */
WhereClause *pWC; /* Shorthand for pScan->pWC */
WhereTerm *pTerm; /* The term being tested */
int k = pScan->k; /* Where to start scanning */
while( pScan->iEquiv<=pScan->nEquiv ){
iCur = pScan->aEquiv[pScan->iEquiv-2];
iColumn = pScan->aEquiv[pScan->iEquiv-1];
iCur = pScan->aiCur[pScan->iEquiv-1];
iColumn = pScan->aiColumn[pScan->iEquiv-1];
while( (pWC = pScan->pWC)!=0 ){
for(pTerm=pWC->a+k; k<pWC->nTerm; k++, pTerm++){
if( pTerm->leftCursor==iCur
&& pTerm->u.leftColumn==iColumn
&& (pScan->iEquiv<=2 || !ExprHasProperty(pTerm->pExpr, EP_FromJoin))
&& (pScan->iEquiv<=1 || !ExprHasProperty(pTerm->pExpr, EP_FromJoin))
){
if( (pTerm->eOperator & WO_EQUIV)!=0
&& pScan->nEquiv<ArraySize(pScan->aEquiv)
&& pScan->nEquiv<ArraySize(pScan->aiCur)
){
int j;
pX = sqlite3ExprSkipCollate(pTerm->pExpr->pRight);
assert( pX->op==TK_COLUMN );
for(j=0; j<pScan->nEquiv; j+=2){
if( pScan->aEquiv[j]==pX->iTable
&& pScan->aEquiv[j+1]==pX->iColumn ){
for(j=0; j<pScan->nEquiv; j++){
if( pScan->aiCur[j]==pX->iTable
&& pScan->aiColumn[j]==pX->iColumn ){
break;
}
}
if( j==pScan->nEquiv ){
pScan->aEquiv[j] = pX->iTable;
pScan->aEquiv[j+1] = pX->iColumn;
pScan->nEquiv += 2;
pScan->aiCur[j] = pX->iTable;
pScan->aiColumn[j] = pX->iColumn;
pScan->nEquiv++;
}
}
if( (pTerm->eOperator & pScan->opMask)!=0 ){
@ -223,8 +223,8 @@ static WhereTerm *whereScanNext(WhereScan *pScan){
}
if( (pTerm->eOperator & (WO_EQ|WO_IS))!=0
&& (pX = pTerm->pExpr->pRight)->op==TK_COLUMN
&& pX->iTable==pScan->aEquiv[0]
&& pX->iColumn==pScan->aEquiv[1]
&& pX->iTable==pScan->aiCur[0]
&& pX->iColumn==pScan->aiColumn[0]
){
testcase( pTerm->eOperator & WO_IS );
continue;
@ -239,7 +239,7 @@ static WhereTerm *whereScanNext(WhereScan *pScan){
}
pScan->pWC = pScan->pOrigWC;
k = 0;
pScan->iEquiv += 2;
pScan->iEquiv++;
}
return 0;
}
@ -285,10 +285,10 @@ static WhereTerm *whereScanInit(
}
pScan->opMask = opMask;
pScan->k = 0;
pScan->aEquiv[0] = iCur;
pScan->aEquiv[1] = iColumn;
pScan->nEquiv = 2;
pScan->iEquiv = 2;
pScan->aiCur[0] = iCur;
pScan->aiColumn[0] = iColumn;
pScan->nEquiv = 1;
pScan->iEquiv = 1;
return whereScanNext(pScan);
}
@ -301,12 +301,10 @@ static WhereTerm *whereScanInit(
** The term returned might by Y=<expr> if there is another constraint in
** the WHERE clause that specifies that X=Y. Any such constraints will be
** identified by the WO_EQUIV bit in the pTerm->eOperator field. The
** aEquiv[] array holds X and all its equivalents, with each SQL variable
** taking up two slots in aEquiv[]. The first slot is for the cursor number
** and the second is for the column number. There are 22 slots in aEquiv[]
** so that means we can look for X plus up to 10 other equivalent values.
** Hence a search for X will return <expr> if X=A1 and A1=A2 and A2=A3
** and ... and A9=A10 and A10=<expr>.
** aiCur[]/iaColumn[] arrays hold X and all its equivalents. There are 11
** slots in aiCur[]/aiColumn[] so that means we can look for X plus up to 10
** other equivalent values. Hence a search for X will return <expr> if X=A1
** and A1=A2 and A2=A3 and ... and A9=A10 and A10=<expr>.
**
** If there are multiple terms in the WHERE clause of the form "X <op> <expr>"
** then try for the one with no dependencies on <expr> - in other words where

3
src/whereInt.h
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@ -291,7 +291,8 @@ struct WhereScan {
unsigned char iEquiv; /* Next unused slot in aEquiv[] */
u32 opMask; /* Acceptable operators */
int k; /* Resume scanning at this->pWC->a[this->k] */
int aEquiv[22]; /* Cursor,Column pairs for equivalence classes */
int aiCur[11]; /* Cursors in the equivalence class */
i16 aiColumn[11]; /* Corresponding column number in the eq-class */
};
/*