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Constant propagation is now restricted to just the WHERE clause. The

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mechanism is changed to take affinity and collation into account.  This
seems to give correct answers.  But the search for constant propagation
costs 4 million cycles in the speed test.

FossilOrigin-Name: 82c67efb723dba387964f690cd459b420e59e3367d9589016597a76531596391
This commit is contained in:
drh
2018-07-27 16:57:11 +00:00
parent 7de7602eb7
commit efad2e2366
8 changed files with 94 additions and 41 deletions
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22
manifest
View File

@@ -1,5 +1,5 @@
C Add\sa\stest\scase\sdemonstrating\sthe\scollation\sproblem\swith\sconstant\spropagation.
D 2018-07-26T23:54:19.662
C Constant\spropagation\sis\snow\srestricted\sto\sjust\sthe\sWHERE\sclause.\sThe\nmechanism\sis\schanged\sto\stake\saffinity\sand\scollation\sinto\saccount.\s\sThis\nseems\sto\sgive\scorrect\sanswers.\s\sBut\sthe\ssearch\sfor\sconstant\spropagation\ncosts\s4\smillion\scycles\sin\sthe\sspeed\stest.
D 2018-07-27T16:57:11.322
F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
F Makefile.in 0a3a6c81e6fcb969ff9106e882f0a08547014ba463cb6beca4c4efaecc924ee6
@@ -450,7 +450,7 @@ F src/date.c ebe1dc7c8a347117bb02570f1a931c62dd78f4a2b1b516f4837d45b7d6426957
F src/dbpage.c 4aa7f26198934dbd002e69418220eae3dbc71b010bbac32bd78faf86b52ce6c3
F src/dbstat.c edabb82611143727511a45ca0859b8cd037851ebe756ae3db289859dd18b6f91
F src/delete.c 4c8c7604277a2041647f96b78f4b9a47858e9217e4fb333d35e7b5ab32c5b57f
F src/expr.c 8187c1be1003230f027bfc5f5a9830aa43d55beb67d87f4a2589d125749fbcfd
F src/expr.c af489eb4dac501d06c1f05b9f27f7fc37a05582b9f9b7724e0e1ccc78ae8a530
F src/fault.c 460f3e55994363812d9d60844b2a6de88826e007
F src/fkey.c b1da9ef8dc834603bb0d28972378a7ce65897847f9a1e89ab800bbdf24c788ee
F src/func.c 7c288b4ce309b5a8b8473514b88e1f8e69a80134509a8c0db8e39c858e367e7f
@@ -498,12 +498,12 @@ F src/printf.c 7f6f3cba8e0c49c19e30a1ff4e9aeda6e06814dcbad4b664a69e1b6cb6e7e365
F src/random.c 80f5d666f23feb3e6665a6ce04c7197212a88384
F src/resolve.c 797088662ed61102485e3070ba3b3f7828bd5ef6a588223ba6865d77d52f6cea
F src/rowset.c 7b7e7e479212e65b723bf40128c7b36dc5afdfac
F src/select.c 81c6517a8d7b6aae805aaa4171187390f72988d1ceec343ad2f51be09513b289
F src/select.c 7d2a980be754def09d3458c9eba5ac781ec2962c3415e6ce6d3e00ca100468f8
F src/shell.c.in f6ebd05c461805a7c708333cd645e74e0a93560d2118f5adb73a75d8c9cf6b01
F src/sqlite.h.in c6451bb876adced3aba5b1682c6317d215c5eceaba21a6ce979e71a0b8d0bf95
F src/sqlite3.rc 5121c9e10c3964d5755191c80dd1180c122fc3a8
F src/sqlite3ext.h 9887b27e69c01e79c2cbe74ef73bf01af5b5703d6a7f0a4371e386d7249cb1c7
F src/sqliteInt.h 0da0d929642cacf99963e406d34e2e3be891a30168f99aefc1cb81c2c545a09b
F src/sqliteInt.h fafe020e6fa39964ffff8ff1b48e2a7f0b394e03c722a746629751d2d31721ae
F src/sqliteLimit.h 1513bfb7b20378aa0041e7022d04acb73525de35b80b252f1b83fedb4de6a76b
F src/status.c 46e7aec11f79dad50965a5ca5fa9de009f7d6bde08be2156f1538a0a296d4d0e
F src/table.c b46ad567748f24a326d9de40e5b9659f96ffff34
@@ -562,7 +562,7 @@ F src/test_window.c cdae419fdcea5bad6dcd9368c685abdad6deb59e9fc8b84b153de513d394
F src/test_wsd.c 41cadfd9d97fe8e3e4e44f61a4a8ccd6f7ca8fe9
F src/threads.c 4ae07fa022a3dc7c5beb373cf744a85d3c5c6c3c
F src/tokenize.c 01e96d1b639c3eb0b9ef90616e766d453935c554f1f7aa86b6db937b79554b97
F src/treeview.c 26c5674083674377b0f41737647802e93ac31f1da89c9b9648501d8a34a44698
F src/treeview.c e7a7f90552bb418533cdd0309b5eb71d4effa50165b880fc8c2001e613577e5f
F src/trigger.c 4ace6d1d5ba9a89822deb287317f33c810440526eafe185c2d8a48c31df1e995
F src/update.c 7b7c768dc415a8d2eb9fd2cea8b524cb29cf354f319700e22f94f262d3f507cb
F src/upsert.c 47edd408cc73f8d3c00a140550d1ad180b407c146285947969dd09874802bf88
@@ -585,8 +585,8 @@ F src/wal.h 8de5d2d3de0956d6f6cb48c83a4012d5f227b8fe940f3a349a4b7e85ebcb492a
F src/walker.c ba7225773931760cf60bf22f34d0cce2588df7ce5ce0f215a52eb88234b55ac4
F src/where.c 2d313b446758317b60626763d0e1285e04b04c061ce94945dcfffad9525badc1
F src/whereInt.h b90ef9b9707ef750eab2a7a080c48fb4900315033274689def32d0cf5a81ebe4
F src/wherecode.c fe23a55294b4c94bf658d2a6eb7996170dd563bf33af4c3e5d71aff3483e4b08
F src/whereexpr.c 571618c67a3eb5ce0f1158c2792c1aee9b4a4a264392fc4fb1b35467f80abf9a
F src/wherecode.c 2c552dfe50d06e0916dbd49a180e4bf0accfce6d17d46a2dfeea8f75d2b5861b
F src/whereexpr.c 7d30c744f37e8bd53811f88fd1d949f6145d24ce77a6f51b252e2b903dc4434e
F src/window.c c61434ce7e35b7d76b3321dec39e10e79061c10eed1e3d7976c87dbdd77aefb5
F test/8_3_names.test ebbb5cd36741350040fd28b432ceadf495be25b2
F test/affinity2.test a6d901b436328bd67a79b41bb0ac2663918fe3bd
@@ -1753,7 +1753,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
P 57eb2abd5b270d65be5e0f138f0d46899fa6091df3ba20b0ea7ef04244a15d48
R 4901cf7d6c93780d74bf2f77c4b5611e
P 50add839fd95665bd67a6ae5de8346fd09e83904bbcbad26fad280dff86d9e93
R 50f5324ffb4955a3d4663001ed61326d
U drh
Z e93689647fb1d0f73e5b2a94dfb414a1
Z f7259f5866467f9069a6566db546a485

2
manifest.uuid
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@@ -1 +1 @@
50add839fd95665bd67a6ae5de8346fd09e83904bbcbad26fad280dff86d9e93
82c67efb723dba387964f690cd459b420e59e3367d9589016597a76531596391

23
src/expr.c
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@@ -328,6 +328,15 @@ CollSeq *sqlite3BinaryCompareCollSeq(
return pColl;
}
/*
** Return true if CollSeq is the default built-in BINARY.
*/
int sqlite3IsBinary(const CollSeq *p){
if( p==0 ) return 1;
if( sqlite3_stricmp(p->zName,"BINARY")==0 ) return 1;
return 0;
}
/*
** Generate code for a comparison operator.
*/
@@ -1839,6 +1848,9 @@ static int exprNodeIsConstant(Walker *pWalker, Expr *pExpr){
testcase( pExpr->op==TK_COLUMN );
testcase( pExpr->op==TK_AGG_FUNCTION );
testcase( pExpr->op==TK_AGG_COLUMN );
if( ExprHasProperty(pExpr, EP_FixedCol) ){
return WRC_Continue;
}
if( pWalker->eCode==3 && pExpr->iTable==pWalker->u.iCur ){
return WRC_Continue;
}
@@ -1927,7 +1939,7 @@ static int exprNodeIsConstantOrGroupBy(Walker *pWalker, Expr *pExpr){
Expr *p = pGroupBy->a[i].pExpr;
if( sqlite3ExprCompare(0, pExpr, p, -1)<2 ){
CollSeq *pColl = sqlite3ExprNNCollSeq(pWalker->pParse, p);
if( sqlite3_stricmp("BINARY", pColl->zName)==0 ){
if( sqlite3IsBinary(pColl) ){
return WRC_Prune;
}
}
@@ -3581,6 +3593,10 @@ expr_code_doover:
}
case TK_COLUMN: {
int iTab = pExpr->iTable;
if( ExprHasProperty(pExpr, EP_FixedCol) ){
pExpr = pExpr->pLeft;
goto expr_code_doover;
}
if( iTab<0 ){
if( pParse->iSelfTab<0 ){
/* Generating CHECK constraints or inserting into partial index */
@@ -4935,14 +4951,15 @@ int sqlite3ExprCompare(Parse *pParse, Expr *pA, Expr *pB, int iTab){
if( sqlite3StrICmp(pA->u.zToken,pB->u.zToken)!=0 ) return 2;
}else if( pA->op==TK_COLLATE ){
if( sqlite3_stricmp(pA->u.zToken,pB->u.zToken)!=0 ) return 2;
}else if( pA->op!=TK_UPLUS && strcmp(pA->u.zToken,pB->u.zToken)!=0 ){
}else if( strcmp(pA->u.zToken,pB->u.zToken)!=0 ){
return 2;
}
}
if( (pA->flags & EP_Distinct)!=(pB->flags & EP_Distinct) ) return 2;
if( ALWAYS((combinedFlags & EP_TokenOnly)==0) ){
if( combinedFlags & EP_xIsSelect ) return 2;
if( sqlite3ExprCompare(pParse, pA->pLeft, pB->pLeft, iTab) ) return 2;
if( (combinedFlags & EP_FixedCol)==0
&& sqlite3ExprCompare(pParse, pA->pLeft, pB->pLeft, iTab) ) return 2;
if( sqlite3ExprCompare(pParse, pA->pRight, pB->pRight, iTab) ) return 2;
if( sqlite3ExprListCompare(pA->x.pList, pB->x.pList, iTab) ) return 2;
assert( (combinedFlags & EP_Reduced)==0 );

76
src/select.c
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@@ -4075,15 +4075,15 @@ static int flattenSubquery(
#endif /* !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) */
/*
** A structure to keep track of all of the column values that must be
** constant in a WHERE clause.
** A structure to keep track of all of the column values that fixed to
** a known value due to WHERE clause constraints of the form COLUMN=VALUE.
*/
typedef struct WhereConst WhereConst;
struct WhereConst {
sqlite3 *db; /* Database pointer, used by sqlite3DbRealloc() */
Parse *pParse; /* Parsing context */
int nConst; /* Number for COLUMN=CONSTANT terms */
int nChng; /* Number of times a constant is propagated */
Expr **apExpr; /* [i*2] is COLUMN and [i*2+1] is CONSTANT */
Expr **apExpr; /* [i*2] is COLUMN and [i*2+1] is VALUE */
};
/*
@@ -4095,23 +4095,26 @@ static void constInsert(
Expr *pValue
){
pConst->nConst++;
pConst->apExpr = sqlite3DbReallocOrFree(pConst->db, pConst->apExpr,
pConst->apExpr = sqlite3DbReallocOrFree(pConst->pParse->db, pConst->apExpr,
pConst->nConst*2*sizeof(Expr*));
if( pConst->apExpr==0 ){
pConst->nConst = 0;
}else{
while( pValue->op==TK_UPLUS ) pValue = pValue->pLeft;
if( ExprHasProperty(pValue, EP_FixedCol) ) pValue = pValue->pLeft;
pConst->apExpr[pConst->nConst*2-2] = pColumn;
pConst->apExpr[pConst->nConst*2-1] = pValue;
}
}
/*
** Find all instances of COLUMN=CONSTANT or CONSTANT=COLUMN in pExpr that
** must be true (that are part of the AND-connected terms) and add each
** to pConst.
** Find all terms of COLUMN=VALUE or VALUE=COLUMN in pExpr where VALUE
** is a constant expression and where the term must be true because it
** is part of the AND-connected terms of the expression. For each term
** found, add it to the pConst structure.
*/
static void findConstInWhere(WhereConst *pConst, Expr *pExpr){
Expr *pRight, *pLeft;
CollSeq *pColl;
if( pExpr==0 ) return;
if( ExprHasProperty(pExpr, EP_FromJoin) ) return;
if( pExpr->op==TK_AND ){
@@ -4120,13 +4123,22 @@ static void findConstInWhere(WhereConst *pConst, Expr *pExpr){
return;
}
if( pExpr->op!=TK_EQ ) return;
assert( pExpr->pRight!=0 );
assert( pExpr->pLeft!=0 );
if( pExpr->pRight->op==TK_COLUMN && sqlite3ExprIsConstant(pExpr->pLeft) ){
constInsert(pConst, pExpr->pRight, pExpr->pLeft);
pRight = pExpr->pRight;
pLeft = pExpr->pLeft;
assert( pRight!=0 );
assert( pLeft!=0 );
pColl = sqlite3BinaryCompareCollSeq(pConst->pParse, pLeft, pRight);
if( !sqlite3IsBinary(pColl) ) return;
if( pRight->op==TK_COLUMN
&& !ExprHasProperty(pRight, EP_FixedCol)
&& sqlite3ExprIsConstant(pLeft)
){
constInsert(pConst, pRight, pLeft);
}else
if( pExpr->pLeft->op==TK_COLUMN && sqlite3ExprIsConstant(pExpr->pRight) ){
constInsert(pConst, pExpr->pLeft, pExpr->pRight);
if( pLeft->op==TK_COLUMN
&& !ExprHasProperty(pLeft, EP_FixedCol)
&& sqlite3ExprIsConstant(pRight) ){
constInsert(pConst, pLeft, pRight);
}
}
@@ -4140,17 +4152,19 @@ static int propagateConstantExprRewrite(Walker *pWalker, Expr *pExpr){
int i;
WhereConst *pConst;
if( pExpr->op!=TK_COLUMN ) return WRC_Continue;
if( ExprHasProperty(pExpr, EP_FixedCol) ) return WRC_Continue;
pConst = pWalker->u.pConst;
for(i=0; i<pConst->nConst; i++){
Expr *pColumn = pConst->apExpr[i*2];
if( pColumn==pExpr ) continue;
if( pColumn->iTable!=pExpr->iTable ) continue;
if( pColumn->iColumn!=pExpr->iColumn ) continue;
/* A match is found. Transform the COLUMN into a CONSTANT */
/* A match is found. Add the EP_FixedCol property */
pConst->nChng++;
ExprClearProperty(pExpr, EP_Leaf);
pExpr->op = TK_UPLUS;
pExpr->pLeft = sqlite3ExprDup(pConst->db, pConst->apExpr[i*2+1], 0);
ExprSetProperty(pExpr, EP_FixedCol);
assert( pExpr->pLeft==0 );
pExpr->pLeft = sqlite3ExprDup(pConst->pParse->db, pConst->apExpr[i*2+1], 0);
break;
}
return WRC_Prune;
@@ -4163,7 +4177,7 @@ static int propagateConstantExprRewrite(Walker *pWalker, Expr *pExpr){
** CONSTANT=COLUMN that must be tree (in other words, if the terms top-level
** AND-connected terms that are not part of a ON clause from a LEFT JOIN)
** then throughout the query replace all other occurrences of COLUMN
** with CONSTANT.
** with CONSTANT within the WHERE clause.
**
** For example, the query:
**
@@ -4174,6 +4188,24 @@ static int propagateConstantExprRewrite(Walker *pWalker, Expr *pExpr){
** SELECT * FROM t1, t2, t3 WHERE t1.a=39 AND t2.b=39 AND t3.c=39
**
** Return true if any transformations where made and false if not.
**
** Implementation note: Constant propagation is tricky due to affinity
** and collating sequence interactions. Consider this example:
**
** CREATE TABLE t1(a INT,b TEXT);
** INSERT INTO t1 VALUES(123,'0123');
** SELECT * FROM t1 WHERE a=123 AND b=a;
** SELECT * FROM t1 WHERE a=123 AND b=123;
**
** The two SELECT statements above should return different answers. b=a
** is alway true because the comparison uses numeric affinity, but b=123
** is false because it uses text affinity and '0123' is not the same as '123'.
** To work around this, the expression tree is not actually changed from
** "b=a" to "b=123" but rather the "a" in "b=a" is tagged with EP_FixedCol
** and the "123" value is hung off of the pLeft pointer. Code generator
** routines know to generate the constant "123" instead of looking up the
** column value. Also, to avoid collation problems, this optimization is
** only attempted if the "a=123" term uses the default BINARY collation.
*/
static int propagateConstants(
Parse *pParse, /* The parsing context */
@@ -4182,7 +4214,7 @@ static int propagateConstants(
WhereConst x;
Walker w;
int nChng = 0;
x.db = pParse->db;
x.pParse = pParse;
do{
x.nConst = 0;
x.nChng = 0;
@@ -4196,8 +4228,8 @@ static int propagateConstants(
w.xSelectCallback2 = 0;
w.walkerDepth = 0;
w.u.pConst = &x;
sqlite3WalkSelect(&w, p);
sqlite3DbFree(x.db, x.apExpr);
sqlite3WalkExpr(&w, p->pWhere);
sqlite3DbFree(x.pParse->db, x.apExpr);
nChng += x.nChng;
}
}while( x.nChng );

3
src/sqliteInt.h
View File

@@ -2479,7 +2479,7 @@ struct Expr {
#define EP_FromJoin 0x000001 /* Originates in ON/USING clause of outer join */
#define EP_Agg 0x000002 /* Contains one or more aggregate functions */
#define EP_HasFunc 0x000004 /* Contains one or more functions of any kind */
/* 0x000008 // available for use */
#define EP_FixedCol 0x000008 /* TK_Column with a known fixed value */
#define EP_Distinct 0x000010 /* Aggregate function with DISTINCT keyword */
#define EP_VarSelect 0x000020 /* pSelect is correlated, not constant */
#define EP_DblQuoted 0x000040 /* token.z was originally in "..." */
@@ -4171,6 +4171,7 @@ int sqlite3MemdbInit(void);
const char *sqlite3ErrStr(int);
int sqlite3ReadSchema(Parse *pParse);
CollSeq *sqlite3FindCollSeq(sqlite3*,u8 enc, const char*,int);
int sqlite3IsBinary(const CollSeq*);
CollSeq *sqlite3LocateCollSeq(Parse *pParse, const char*zName);
CollSeq *sqlite3ExprCollSeq(Parse *pParse, Expr *pExpr);
CollSeq *sqlite3ExprNNCollSeq(Parse *pParse, Expr *pExpr);

3
src/treeview.c
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@@ -374,6 +374,9 @@ void sqlite3TreeViewExpr(TreeView *pView, const Expr *pExpr, u8 moreToFollow){
sqlite3TreeViewLine(pView, "{%d:%d}%s",
pExpr->iTable, pExpr->iColumn, zFlgs);
}
if( ExprHasProperty(pExpr, EP_FixedCol) ){
sqlite3TreeViewExpr(pView, pExpr->pLeft, 0);
}
break;
}
case TK_INTEGER: {

2
src/wherecode.c
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@@ -883,7 +883,7 @@ static int codeCursorHintIsOrFunction(Walker *pWalker, Expr *pExpr){
static int codeCursorHintFixExpr(Walker *pWalker, Expr *pExpr){
int rc = WRC_Continue;
struct CCurHint *pHint = pWalker->u.pCCurHint;
if( pExpr->op==TK_COLUMN ){
if( pExpr->op==TK_COLUMN && !ExprHasProperty(pExpr, EP_FixedCol) ){
if( pExpr->iTable!=pHint->iTabCur ){
Vdbe *v = pWalker->pParse->pVdbe;
int reg = ++pWalker->pParse->nMem; /* Register for column value */

4
src/whereexpr.c
View File

@@ -859,7 +859,7 @@ static int termIsEquivalence(Parse *pParse, Expr *pExpr){
return 0;
}
pColl = sqlite3BinaryCompareCollSeq(pParse, pExpr->pLeft, pExpr->pRight);
if( pColl==0 || sqlite3StrICmp(pColl->zName, "BINARY")==0 ) return 1;
if( sqlite3IsBinary(pColl) ) return 1;
return sqlite3ExprCollSeqMatch(pParse, pExpr->pLeft, pExpr->pRight);
}
@@ -1450,7 +1450,7 @@ void sqlite3WhereClauseClear(WhereClause *pWC){
*/
Bitmask sqlite3WhereExprUsageNN(WhereMaskSet *pMaskSet, Expr *p){
Bitmask mask;
if( p->op==TK_COLUMN ){
if( p->op==TK_COLUMN && !ExprHasProperty(p, EP_FixedCol) ){
return sqlite3WhereGetMask(pMaskSet, p->iTable);
}else if( ExprHasProperty(p, EP_TokenOnly|EP_Leaf) ){
assert( p->op!=TK_IF_NULL_ROW );