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Initial implementation of the unlikely() SQL function used as a hint to

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the query planner.

FossilOrigin-Name: 036fc37a034093a4c6fc190633bd41c2b7230d77
This commit is contained in:
drh 2013-09-06 15:23:29 +00:00
parent d36e104112
commit cca9f3d291
8 changed files with 118 additions and 31 deletions
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25
manifest
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@ -1,5 +1,5 @@
C Combine\sthe\sFuncDef.iPrefEnc\sand\sFuncDef.flags\sfields\sinto\sa\ssingle\nnew\sFuncDef.funcFlags\sfield.
D 2013-09-06T13:10:12.385
C Initial\simplementation\sof\sthe\sunlikely()\sSQL\sfunction\sused\sas\sa\shint\sto\nthe\squery\splanner.
D 2013-09-06T15:23:29.191
F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
F Makefile.in 5e41da95d92656a5004b03d3576e8b226858a28e
F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@ -172,10 +172,10 @@ F src/complete.c dc1d136c0feee03c2f7550bafc0d29075e36deac
F src/ctime.c ea4b7f3623a0fcb1146e7f245d7410033e86859c
F src/date.c 067a81c9942c497aafd2c260e13add8a7d0c7dd4
F src/delete.c 2dc64ca360b7d7da481183ea920a813a0c203c97
F src/expr.c 33ae44812d25799000dbcfd54bb2142b30cdd049
F src/expr.c d0ed048b3b3c97fddbcccb8df43cc39b89e682c2
F src/fault.c 160a0c015b6c2629d3899ed2daf63d75754a32bb
F src/fkey.c be866cd8c4fa6cae98ba33109578fd1a3311ee5b
F src/func.c 7650d35651bb0ca903d24f4e5e944bfdaac9f152
F src/func.c a297b1f3cf48dd483f5453b7155bc5e8f4ca1fc2
F src/global.c 5caf4deab621abb45b4c607aad1bd21c20aac759
F src/hash.c ac3470bbf1ca4ae4e306a8ecb0fdf1731810ffe4
F src/hash.h 8890a25af81fb85a9ad7790d32eedab4b994da22
@ -214,14 +214,14 @@ F src/pragma.c 3aa3d8c8623b7b71c5b1bfb72dcc31fb0c25665f
F src/prepare.c fa6988589f39af8504a61731614cd4f6ae71554f
F src/printf.c da9119eb31a187a4b99f60aa4a225141c0ebb74b
F src/random.c 0b2dbc37fdfbfa6bd455b091dfcef5bdb32dba68
F src/resolve.c 9d53899cc6e1f4ec0b4632d07e97d57827bf63b9
F src/resolve.c 748618c3df7f37f2cd33c8834770b1e34f9b1185
F src/rowset.c 64655f1a627c9c212d9ab497899e7424a34222e0
F src/select.c 9239586282bd146ec5843a2cde7d54cd7816cf78
F src/shell.c d920a891ca09b8bd262cced7fb0ab9d723f7a747
F src/sqlite.h.in ec40aa958a270416fb04b4f72210357bf163d2c5
F src/sqlite3.rc fea433eb0a59f4c9393c8e6d76a6e2596b1fe0c0
F src/sqlite3ext.h 886f5a34de171002ad46fae8c36a7d8051c190fc
F src/sqliteInt.h 32e959dba9899360ce4ae3cd6cc77b4a8df277e8
F src/sqliteInt.h fd9005fab1cd063f5c4e76a2120efc080b43750a
F src/sqliteLimit.h 164b0e6749d31e0daa1a4589a169d31c0dec7b3d
F src/status.c 7ac05a5c7017d0b9f0b4bcd701228b784f987158
F src/table.c 2cd62736f845d82200acfa1287e33feb3c15d62e
@ -290,7 +290,7 @@ F src/vtab.c 5a423b042eb1402ef77697d03d6a67378d97bc8d
F src/wal.c 7dc3966ef98b74422267e7e6e46e07ff6c6eb1b4
F src/wal.h df01efe09c5cb8c8e391ff1715cca294f89668a4
F src/walker.c 4fa43583d0a84b48f93b1e88f11adf2065be4e73
F src/where.c 06c249a5137575ecf4d527e5a1dadb1087e4375c
F src/where.c c9f8ae51797bebfbfa49b9e5bede6fc142b44262
F test/8_3_names.test ebbb5cd36741350040fd28b432ceadf495be25b2
F test/aggerror.test a867e273ef9e3d7919f03ef4f0e8c0d2767944f2
F test/aggnested.test 45c0201e28045ad38a530b5a144b73cd4aa2cfd6
@ -308,7 +308,7 @@ F test/analyze5.test 765c4e284aa69ca172772aa940946f55629bc8c4
F test/analyze6.test 19151da2c4e918905d2081b74ac5c4d47fc850ab
F test/analyze7.test bb1409afc9e8629e414387ef048b8e0e3e0bdc4f
F test/analyze8.test 093d15c1c888eed5034304a98c992f7360130b88
F test/analyze9.test 4a48461d71a7b4a958570c580495a97e842e2700
F test/analyze9.test e688c7289d3d33b7185e2c2afcac6a9f095563a3
F test/analyzeA.test 1a5c40079894847976d983ca39c707aaa44b6944
F test/analyzeB.test 8bf35ee0a548aea831bf56762cb8e7fdb1db083d
F test/async.test 1d0e056ba1bb9729283a0f22718d3a25e82c277b
@ -1111,7 +1111,10 @@ F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
F tool/warnings.sh fbc018d67fd7395f440c28f33ef0f94420226381
F tool/wherecosttest.c f407dc4c79786982a475261866a161cd007947ae
F tool/win/sqlite.vsix 97894c2790eda7b5bce3cc79cb2a8ec2fde9b3ac
P a99a53b81e29c9514b85318bea028d1667e5f760
R 8c10a6011eb52c6098e833ca515e6c77
P 97b10e66e98e84755aa577f8da017bf1aea2056c
R fcd7cd29a90a12a870cace66939b8877
T *branch * unlikely-func
T *sym-unlikely-func *
T -sym-trunk *
U drh
Z c7e49c79214a66374f550dcdb7a70012
Z 2a30cee668099b5c8e0e2b447ac67feb

2
manifest.uuid
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@ -1 +1 @@
97b10e66e98e84755aa577f8da017bf1aea2056c
036fc37a034093a4c6fc190633bd41c2b7230d77

18
src/expr.c
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@ -89,8 +89,16 @@ Expr *sqlite3ExprAddCollateString(Parse *pParse, Expr *pExpr, const char *zC){
** an expression.
*/
Expr *sqlite3ExprSkipCollate(Expr *pExpr){
while( pExpr && (pExpr->op==TK_COLLATE || pExpr->op==TK_AS) ){
while( pExpr ){
if( pExpr->op==TK_COLLATE || pExpr->op==TK_AS ){
pExpr = pExpr->pLeft;
}else if( ExprHasAnyProperty(pExpr, EP_Hint) ){
assert( !ExprHasProperty(pExpr, EP_xIsSelect) );
assert( pExpr->x.pList->nExpr>0 );
pExpr = pExpr->x.pList->a[0].pExpr;
}else{
break;
}
}
return pExpr;
}
@ -2649,6 +2657,14 @@ int sqlite3ExprCodeTarget(Parse *pParse, Expr *pExpr, int target){
break;
}
/* The UNLIKELY() function is a no-op. The result is the value
** of the first argument.
*/
if( pDef->funcFlags & SQLITE_FUNC_UNLIKELY ){
assert( nFarg>=1 );
sqlite3ExprCode(pParse, pFarg->a[0].pExpr, target);
break;
}
if( pFarg ){
r1 = sqlite3GetTempRange(pParse, nFarg);

20
src/func.c
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@ -418,14 +418,14 @@ static void lowerFunc(sqlite3_context *context, int argc, sqlite3_value **argv){
}
/*
** The COALESCE() and IFNULL() functions are implemented as VDBE code so
** that unused argument values do not have to be computed. However, we
** still need some kind of function implementation for this routines in
** the function table. That function implementation will never be called
** so it doesn't matter what the implementation is. We might as well use
** the "version()" function as a substitute.
** Some functions like COALESCE() and IFNULL() and UNLIKELY() are implemented
** as VDBE code so that unused argument values do not have to be computed.
** However, we still need some kind of function implementation for this
** routines in the function table. The noopFunc macro provides this.
** noopFunc will never be called so it doesn't matter what the implementation
** is. We might as well use the "version()" function as a substitute.
*/
#define ifnullFunc versionFunc /* Substitute function - never called */
#define noopFunc versionFunc /* Substitute function - never called */
/*
** Implementation of random(). Return a random integer.
@ -1659,9 +1659,11 @@ void sqlite3RegisterGlobalFunctions(void){
FUNCTION(lower, 1, 0, 0, lowerFunc ),
FUNCTION(coalesce, 1, 0, 0, 0 ),
FUNCTION(coalesce, 0, 0, 0, 0 ),
FUNCTION2(coalesce, -1, 0, 0, ifnullFunc, SQLITE_FUNC_COALESCE),
FUNCTION2(coalesce, -1, 0, 0, noopFunc, SQLITE_FUNC_COALESCE),
FUNCTION(hex, 1, 0, 0, hexFunc ),
FUNCTION2(ifnull, 2, 0, 0, ifnullFunc, SQLITE_FUNC_COALESCE),
FUNCTION2(ifnull, 2, 0, 0, noopFunc, SQLITE_FUNC_COALESCE),
FUNCTION2(unlikely, 1, 0, 0, noopFunc, SQLITE_FUNC_UNLIKELY),
FUNCTION2(unlikely, 2, 0, 0, noopFunc, SQLITE_FUNC_UNLIKELY),
FUNCTION(random, 0, 0, 0, randomFunc ),
FUNCTION(randomblob, 1, 0, 0, randomBlob ),
FUNCTION(nullif, 2, 0, 1, nullifFunc ),

25
src/resolve.c
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@ -570,6 +570,18 @@ static void notValidCheckConstraint(
# define notValidCheckConstraint(P,N,M)
#endif
/*
** Expression p should encode a floating point value between 1.0 and 0.0.
** Return 1024 times this value. Or return -1 if p is not a floating point
** value between 1.0 and 0.0.
*/
static int exprProbability(Expr *p){
double r = -1.0;
if( p->op!=TK_FLOAT ) return -1;
sqlite3AtoF(p->u.zToken, &r, sqlite3Strlen30(p->u.zToken), SQLITE_UTF8);
if( r<0.0 || r>1.0 ) return -1;
return (int)(r*1000.0);
}
/*
** This routine is callback for sqlite3WalkExpr().
@ -683,6 +695,19 @@ static int resolveExprStep(Walker *pWalker, Expr *pExpr){
}
}else{
is_agg = pDef->xFunc==0;
if( pDef->funcFlags & SQLITE_FUNC_UNLIKELY ){
ExprSetProperty(pExpr, EP_Hint);
if( n==2 ){
pExpr->iTable = exprProbability(pList->a[1].pExpr);
if( pExpr->iTable<0 ){
sqlite3ErrorMsg(pParse, "second parameter to unlikely() must be "
"between 0.0 and 1.0");
pNC->nErr++;
}
}else{
pExpr->iTable = 100;
}
}
}
#ifndef SQLITE_OMIT_AUTHORIZATION
if( pDef ){

5
src/sqliteInt.h
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@ -1752,7 +1752,8 @@ struct Expr {
#endif
int iTable; /* TK_COLUMN: cursor number of table holding column
** TK_REGISTER: register number
** TK_TRIGGER: 1 -> new, 0 -> old */
** TK_TRIGGER: 1 -> new, 0 -> old
** EP_Hint: 1000 times likelihood */
ynVar iColumn; /* TK_COLUMN: column index. -1 for rowid.
** TK_VARIABLE: variable number (always >= 1). */
i16 iAgg; /* Which entry in pAggInfo->aCol[] or ->aFunc[] */
@ -1780,7 +1781,7 @@ struct Expr {
#define EP_FixedDest 0x0200 /* Result needed in a specific register */
#define EP_IntValue 0x0400 /* Integer value contained in u.iValue */
#define EP_xIsSelect 0x0800 /* x.pSelect is valid (otherwise x.pList is) */
#define EP_Hint 0x1000 /* Not used */
#define EP_Hint 0x1000 /* The UNLIKELY() SQL function */
#define EP_Reduced 0x2000 /* Expr struct is EXPR_REDUCEDSIZE bytes only */
#define EP_TokenOnly 0x4000 /* Expr struct is EXPR_TOKENONLYSIZE bytes only */
#define EP_Static 0x8000 /* Held in memory not obtained from malloc() */

50
src/where.c
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@ -52,12 +52,13 @@ typedef struct WhereOrSet WhereOrSet;
** Cost X is tracked as 10*log2(X) stored in a 16-bit integer. The
** maximum cost for ordinary tables is 64*(2**63) which becomes 6900.
** (Virtual tables can return a larger cost, but let's assume they do not.)
** So all costs can be stored in a 16-bit unsigned integer without risk
** So all costs can be stored in a 16-bit integer without risk
** of overflow.
**
** Costs are estimates, so no effort is made to compute 10*log2(X) exactly.
** Instead, a close estimate is used. Any value of X<=1 is stored as 0.
** X=2 is 10. X=3 is 16. X=1000 is 99. etc.
** Instead, a close estimate is used. Any value of X=1 is stored as 0.
** X=2 is 10. X=3 is 16. X=1000 is 99. etc. Negative values are allowed.
** A WhereCost of -10 means 0.5. WhereCost of -20 means 0.25. And so forth.
**
** The tool/wherecosttest.c source file implements a command-line program
** that will convert WhereCosts to integers, convert integers to WhereCosts
@ -65,7 +66,7 @@ typedef struct WhereOrSet WhereOrSet;
** command-line program is a useful utility to have around when working with
** this module.
*/
typedef unsigned short int WhereCost;
typedef short int WhereCost;
/*
** This object contains information needed to implement a single nested
@ -268,6 +269,7 @@ struct WhereTerm {
WhereOrInfo *pOrInfo; /* Extra information if (eOperator & WO_OR)!=0 */
WhereAndInfo *pAndInfo; /* Extra information if (eOperator& WO_AND)!=0 */
} u;
WhereCost truthProb; /* Probability of truth for this expression */
u16 eOperator; /* A WO_xx value describing <op> */
u8 wtFlags; /* TERM_xxx bit flags. See below */
u8 nChild; /* Number of children that must disable us */
@ -642,6 +644,9 @@ static void whereClauseClear(WhereClause *pWC){
}
}
/* Forward declaration */
static WhereCost whereCost(tRowcnt x);
/*
** Add a single new WhereTerm entry to the WhereClause object pWC.
** The new WhereTerm object is constructed from Expr p and with wtFlags.
@ -683,6 +688,11 @@ static int whereClauseInsert(WhereClause *pWC, Expr *p, u8 wtFlags){
pWC->nSlot = sqlite3DbMallocSize(db, pWC->a)/sizeof(pWC->a[0]);
}
pTerm = &pWC->a[idx = pWC->nTerm++];
if( p && ExprHasAnyProperty(p, EP_Hint) ){
pTerm->truthProb = whereCost(p->iTable) - 99;
}else{
pTerm->truthProb = -1;
}
pTerm->pExpr = sqlite3ExprSkipCollate(p);
pTerm->wtFlags = wtFlags;
pTerm->pWC = pWC;
@ -4257,6 +4267,32 @@ whereLoopInsert_noop:
return SQLITE_OK;
}
/*
** Adjust the WhereLoop.nOut value downward to account for terms of the
** WHERE clause that reference the loop but which are not used by an
** index.
**
** In the current implementation, the first extra WHERE clause term reduces
** the number of output rows by a factor of 10 and each additional term
** reduces the number of output rows by sqrt(2).
*/
static void whereLoopOutputAdjust(WhereClause *pWC, WhereLoop *pLoop, int iCur){
WhereTerm *pTerm;
Bitmask notAllowed = ~(pLoop->prereq|pLoop->maskSelf);
int x = 0;
int i;
for(i=pWC->nTerm, pTerm=pWC->a; i>0; i--, pTerm++){
if( (pTerm->wtFlags & TERM_VIRTUAL)!=0 ) continue;
if( (pTerm->prereqAll & pLoop->maskSelf)==0 ) continue;
if( (pTerm->prereqAll & notAllowed)!=0 ) continue;
x += pTerm->truthProb;
}
for(i=pLoop->nLTerm-1; i>=0; i--){
x -= pLoop->aLTerm[i]->truthProb;
}
if( x<0 ) pLoop->nOut += x;
}
/*
** We have so far matched pBuilder->pNew->u.btree.nEq terms of the index pIndex.
** Try to match one more.
@ -4423,7 +4459,7 @@ static int whereLoopAddBtreeIndex(
}
/* Step cost for each output row */
pNew->rRun = whereCostAdd(pNew->rRun, pNew->nOut);
/* TBD: Adjust nOut for additional constraints */
whereLoopOutputAdjust(pBuilder->pWC, pNew, pSrc->iCursor);
rc = whereLoopInsert(pBuilder, pNew);
if( (pNew->wsFlags & WHERE_TOP_LIMIT)==0
&& pNew->u.btree.nEq<(pProbe->nColumn + (pProbe->zName!=0))
@ -4627,7 +4663,9 @@ static int whereLoopAddBtree(
** index scans so that a covering index scan will be favored over
** a table scan. */
pNew->rRun = whereCostAdd(rSize,rLogSize) + 16;
whereLoopOutputAdjust(pWC, pNew, pSrc->iCursor);
rc = whereLoopInsert(pBuilder, pNew);
pNew->nOut = rSize;
if( rc ) break;
}else{
Bitmask m = pSrc->colUsed & ~columnsInIndex(pProbe);
@ -4659,7 +4697,9 @@ static int whereLoopAddBtree(
** which we will simplify to just N*log2(N) */
pNew->rRun = rSize + rLogSize;
}
whereLoopOutputAdjust(pWC, pNew, pSrc->iCursor);
rc = whereLoopInsert(pBuilder, pNew);
pNew->nOut = rSize;
if( rc ) break;
}
}

2
test/analyze9.test
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@ -805,6 +805,7 @@ do_test 16.1 {
ANALYZE;
}
set nByte2 [lindex [sqlite3_db_status db SCHEMA_USED 0] 1]
puts "$nByte $nByte2"
expr {$nByte2 > $nByte+950 && $nByte2 < $nByte+1050}
} {1}
@ -950,4 +951,3 @@ for {set i 0} {$i<16} {incr i} {
}
finish_test