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Further refinements to table order selection on join query planning.

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FossilOrigin-Name: defaf0d99a807027f8883bf821b6482025f9f54e
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drh
2010-04-15 01:04:54 +00:00
parent 1e0f4a83d6
commit ed754ce2cc
8 changed files with 78 additions and 56 deletions
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28
manifest
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@@ -1,8 +1,8 @@
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
C The\squery\splanner\suses\snon-indexable\sWHERE\sclause\sterms\sto\sreduce\sthe\nestimated\snumber\sof\soutput\srows,\sthen\suses\sthe\sestimated\snumber\sof\soutput\nrows\sas\sa\stie-breaker\swhen\schoosing\stable\sorder.
D 2010-04-14T19:01:45
C Further\srefinements\sto\stable\sorder\sselection\son\sjoin\squery\splanning.
D 2010-04-15T01:04:54
F Makefile.arm-wince-mingw32ce-gcc fcd5e9cd67fe88836360bb4f9ef4cb7f8e2fb5a0
F Makefile.in 4f2f967b7e58a35bb74fb7ec8ae90e0f4ca7868b
F Makefile.linux-gcc d53183f4aa6a9192d249731c90dbdffbd2c68654
@@ -225,7 +225,7 @@ F src/vdbemem.c 2a82f455f6ca6f78b59fb312f96054c04ae0ead1
F src/vdbetrace.c 864cef96919323482ebd9986f2132435115e9cc2
F src/vtab.c a0f8a40274e4261696ef57aa806de2776ab72cda
F src/walker.c 3112bb3afe1d85dc52317cb1d752055e9a781f8f
F src/where.c 458b6e0d5e3e4eaaf75e352a88641ab2d7e21cad
F src/where.c 74ff6f0d96b3190f8abe2ceaa09858441749e8ff
F test/aggerror.test a867e273ef9e3d7919f03ef4f0e8c0d2767944f2
F test/alias.test 4529fbc152f190268a15f9384a5651bbbabc9d87
F test/all.test 14165b3e32715b700b5f0cbf8f6e3833dda0be45
@@ -558,7 +558,7 @@ F test/schema.test 8f7999be894260f151adf15c2c7540f1c6d6a481
F test/schema2.test 906408621ea881fdb496d878b1822572a34e32c5
F test/securedel.test 328d2921c0ca49bdd3352e516b0377fc07143254
F test/select1.test f67ca2dfc05df41c7b86eb32ca409b427a5f43b0
F test/select2.test 9735da20ccd41e42bf2b4c19fd939141b591adae
F test/select2.test 352480e0e9c66eda9c3044e412abdf5be0215b56
F test/select3.test 2ce595f8fb8e2ac10071d3b4e424cadd4634a054
F test/select4.test 44aa6e7110592e18110b0b9cf5c024d37d23be17
F test/select5.test e758b8ef94f69b111df4cb819008856655dcd535
@@ -723,7 +723,7 @@ F test/trigger6.test 0e411654f122552da6590f0b4e6f781048a4a9b9
F test/trigger7.test 72feaf8dbc52cea84de0c3e6ce7559ff19c479af
F test/trigger8.test 30cb0530bd7c4728055420e3f739aa00412eafa4
F test/trigger9.test 5b0789f1c5c4600961f8e68511b825b87be53e31
F test/triggerA.test 0718ad2d9bfef27c7af00e636df79bee6b988da7
F test/triggerA.test eaf11a29db2a11967d2d4b49d37f92bce598194e
F test/triggerB.test 56780c031b454abac2340dbb3b71ac5c56c3d7fe
F test/triggerC.test cac41fe31adc1abb9fa08532762fc2b4f662ab03
F test/triggerD.test c6add3817351451e419f6ff9e9a259b02b6e2de7
@@ -759,12 +759,12 @@ F test/vtab_err.test 0d4d8eb4def1d053ac7c5050df3024fd47a3fbd8
F test/vtab_shared.test 0eff9ce4f19facbe0a3e693f6c14b80711a4222d
F test/where.test de337a3fe0a459ec7c93db16a519657a90552330
F test/where2.test 45eacc126aabb37959a387aa83e59ce1f1f03820
F test/where3.test 97d3936e6a443b968f1a61cdcc0f673252000e94
F test/where3.test aa44a9b29e8c9f3d7bb94a3bb3a95b31627d520d
F test/where4.test e9b9e2f2f98f00379e6031db6a6fca29bae782a2
F test/where5.test fdf66f96d29a064b63eb543e28da4dfdccd81ad2
F test/where6.test 5da5a98cec820d488e82708301b96cb8c18a258b
F test/where7.test fdd58ab9dec9f97679e65d4414bf5e07d725d79f
F test/where8.test 2bb8ea44b745fcc93db150fac9ce33d12e499760
F test/where7.test a0a92b8ce48d9c027fbdd7b764c7de1e1213575a
F test/where8.test a6c740fd286d7883e274e17b6230a9d672a7ab1f
F test/where8m.test da346596e19d54f0aba35ebade032a7c47d79739
F test/where9.test be19e1a92f80985c1a121b4678bf7d2123eaa623
F test/whereA.test 24c234263c8fe358f079d5e57d884fb569d2da0a
@@ -800,14 +800,14 @@ F tool/speedtest2.tcl ee2149167303ba8e95af97873c575c3e0fab58ff
F tool/speedtest8.c 2902c46588c40b55661e471d7a86e4dd71a18224
F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e
F tool/vdbe-compress.tcl d70ea6d8a19e3571d7ab8c9b75cba86d1173ff0f
P 012cf101bf8be9e39c138786ea5a5039b8131e55
R e6913462c9fc35ffdd8fb296dee81dc4
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R ac19ec910df4152a1528b71c1365be54
U drh
Z b112ddd6d5441568434e7011a246cd66
Z 406deb0be8ed4b7e4bb6e640f59e7f15
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2
manifest.uuid
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@@ -1 +1 @@
b87cb0c2bd9c52a938795a974e101879b81210e3
defaf0d99a807027f8883bf821b6482025f9f54e

81
src/where.c
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@@ -1575,6 +1575,11 @@ static void bestOrClauseIndex(
WhereTerm * const pWCEnd = &pWC->a[pWC->nTerm]; /* End of pWC->a[] */
WhereTerm *pTerm; /* A single term of the WHERE clause */
/* No OR-clause optimization allowed if the NOT INDEXED clause is used */
if( pSrc->notIndexed ){
return;
}
/* Search the WHERE clause terms for a usable WO_OR term. */
for(pTerm=pWC->a; pTerm<pWCEnd; pTerm++){
if( pTerm->eOperator==WO_OR
@@ -1617,8 +1622,9 @@ static void bestOrClauseIndex(
/* If there is an ORDER BY clause, increase the scan cost to account
** for the cost of the sort. */
if( pOrderBy!=0 ){
WHERETRACE(("... sorting increases OR cost %.9g to %.9g\n",
rTotal, rTotal+nRow*estLog(nRow)));
rTotal += nRow*estLog(nRow);
WHERETRACE(("... sorting increases OR cost to %.9g\n", rTotal));
}
/* If the cost of scanning using this OR term for optimization is
@@ -2569,14 +2575,14 @@ static void bestBtreeIndex(
** Set to true if there was at least one "x IN (SELECT ...)" term used
** in determining the value of nInMul.
**
** nBound:
** estBound:
** An estimate on the amount of the table that must be searched. A
** value of 100 means the entire table is searched. Range constraints
** might reduce this to a value less than 100 to indicate that only
** a fraction of the table needs searching. In the absence of
** sqlite_stat2 ANALYZE data, a single inequality reduces the search
** space to 1/3rd its original size. So an x>? constraint reduces
** nBound to 33. Two constraints (x>? AND x<?) reduce nBound to 11.
** estBound to 33. Two constraints (x>? AND x<?) reduce estBound to 11.
**
** bSort:
** Boolean. True if there is an ORDER BY clause that will require an
@@ -2598,7 +2604,8 @@ static void bestBtreeIndex(
int nEq;
int bInEst = 0;
int nInMul = 1;
int nBound = 100;
int estBound = 100;
int nBound = 0; /* Number of range constraints seen */
int bSort = 0;
int bLookup = 0;
WhereTerm *pTerm; /* A single term of the WHERE clause */
@@ -2624,18 +2631,20 @@ static void bestBtreeIndex(
used |= pTerm->prereqRight;
}
/* Determine the value of nBound. */
/* Determine the value of estBound. */
if( nEq<pProbe->nColumn ){
int j = pProbe->aiColumn[nEq];
if( findTerm(pWC, iCur, j, notReady, WO_LT|WO_LE|WO_GT|WO_GE, pIdx) ){
WhereTerm *pTop = findTerm(pWC, iCur, j, notReady, WO_LT|WO_LE, pIdx);
WhereTerm *pBtm = findTerm(pWC, iCur, j, notReady, WO_GT|WO_GE, pIdx);
whereRangeScanEst(pParse, pProbe, nEq, pBtm, pTop, &nBound);
whereRangeScanEst(pParse, pProbe, nEq, pBtm, pTop, &estBound);
if( pTop ){
nBound = 1;
wsFlags |= WHERE_TOP_LIMIT;
used |= pTop->prereqRight;
}
if( pBtm ){
nBound++;
wsFlags |= WHERE_BTM_LIMIT;
used |= pBtm->prereqRight;
}
@@ -2704,8 +2713,8 @@ static void bestBtreeIndex(
/* Adjust the number of rows and the cost downward to reflect rows
** that are excluded by range constraints.
*/
nRow = (nRow * (double)nBound) / (double)100;
cost = (cost * (double)nBound) / (double)100;
nRow = (nRow * (double)estBound) / (double)100;
cost = (cost * (double)estBound) / (double)100;
/* Add in the estimated cost of sorting the result
*/
@@ -2727,24 +2736,36 @@ static void bestBtreeIndex(
** of output rows, adjust the nRow value accordingly. This only
** matters if the current index is the least costly, so do not bother
** with this step if we already know this index will not be chosen.
** Also, never reduce the output row count below 2 using this step.
*/
if( nRow>2 && cost<=pCost->rCost ){
int k;
int nSkip = nEq;
int nSkipEq = nEq;
int nSkipRange = nBound;
Bitmask thisTab = getMask(pWC->pMaskSet, iCur);
for(pTerm=pWC->a, k=pWC->nTerm; nRow>2 && k; k--, pTerm++){
if( pTerm->wtFlags & TERM_VIRTUAL ) continue;
if( (pTerm->prereqAll & notReady)!=thisTab ) continue;
if( pTerm->eOperator & (WO_EQ|WO_IN|WO_ISNULL) ){
if( nSkip ){
if( nSkipEq ){
/* Ignore the first nEq equality matches since the index
** has already accounted for these */
nSkip--;
nSkipEq--;
}else{
/* Assume each additional equality match reduces the result
** set size by a factor of 10 */
nRow /= 10;
}
}else if( pTerm->eOperator & (WO_LT|WO_LE|WO_GT|WO_GE) ){
if( nSkipRange ){
/* Ignore the first nBound range constraints since the index
** has already accounted for these */
nSkipRange--;
}else{
/* Assume each additional range constraint reduces the result
** set size by a factor of 3 */
nRow /= 3;
}
}else{
/* Any other expression lowers the output row count by half */
nRow /= 2;
@@ -2755,17 +2776,18 @@ static void bestBtreeIndex(
WHERETRACE((
"%s(%s): nEq=%d nInMul=%d nBound=%d bSort=%d bLookup=%d wsFlags=0x%x\n"
"%s(%s): nEq=%d nInMul=%d estBound=%d bSort=%d bLookup=%d wsFlags=0x%x\n"
" notReady=0x%llx nRow=%.2f cost=%.2f used=0x%llx\n",
pSrc->pTab->zName, (pIdx ? pIdx->zName : "ipk"),
nEq, nInMul, nBound, bSort, bLookup, wsFlags, notReady, nRow, cost, used
nEq, nInMul, estBound, bSort, bLookup, wsFlags,
notReady, nRow, cost, used
));
/* If this index is the best we have seen so far, then record this
** index and its cost in the pCost structure.
*/
if( (!pIdx || wsFlags)
&& (cost<pCost->rCost || (cost==pCost->rCost && nRow<pCost->nRow))
&& (cost<pCost->rCost || (cost<=pCost->rCost && nRow<pCost->nRow))
){
pCost->rCost = cost;
pCost->nRow = nRow;
@@ -4015,20 +4037,25 @@ WhereInfo *sqlite3WhereBegin(
bestPlan.rCost = SQLITE_BIG_DBL;
/* Loop through the remaining entries in the FROM clause to find the
** next nested loop. The FROM clause entries may be iterated through
** next nested loop. The loop tests all FROM clause entries
** either once or twice.
**
** The first iteration, which is always performed, searches for the
** FROM clause entry that permits the lowest-cost, "optimal" scan. In
** The first test is always performed if there are two or more entries
** remaining and never performed if there is only one FROM clause entry
** to choose from. The first test looks for an "optimal" scan. In
** this context an optimal scan is one that uses the same strategy
** for the given FROM clause entry as would be selected if the entry
** were used as the innermost nested loop. In other words, a table
** is chosen such that the cost of running that table cannot be reduced
** by waiting for other tables to run first.
** by waiting for other tables to run first. This "optimal" test works
** by first assuming that the FROM clause is on the inner loop and finding
** its query plan, then checking to see if that query plan uses any
** other FROM clause terms that are notReady. If no notReady terms are
** used then the "optimal" query plan works.
**
** The second iteration is only performed if no optimal scan strategies
** were found by the first. This iteration is used to search for the
** lowest cost scan overall.
** The second loop iteration is only performed if no optimal scan
** strategies were found by the first loop. This 2nd iteration is used to
** search for the lowest cost scan overall.
**
** Previous versions of SQLite performed only the second iteration -
** the next outermost loop was always that with the lowest overall
@@ -4046,9 +4073,8 @@ WhereInfo *sqlite3WhereBegin(
** algorithm may choose to use t2 for the outer loop, which is a much
** costlier approach.
*/
for(isOptimal=1; isOptimal>=0 && bestJ<0; isOptimal--){
Bitmask mask = (isOptimal ? 0 : notReady);
assert( (nTabList-iFrom)>1 || isOptimal );
for(isOptimal=(iFrom<nTabList-1); isOptimal>=0; isOptimal--){
Bitmask mask; /* Mask of tables not yet ready */
for(j=iFrom, pTabItem=&pTabList->a[j]; j<nTabList; j++, pTabItem++){
int doNotReorder; /* True if this table should not be reordered */
WhereCost sCost; /* Cost information from best[Virtual]Index() */
@@ -4061,6 +4087,7 @@ WhereInfo *sqlite3WhereBegin(
if( j==iFrom ) iFrom++;
continue;
}
mask = (isOptimal ? m : notReady);
pOrderBy = ((i==0 && ppOrderBy )?*ppOrderBy:0);
assert( pTabItem->pTab );
@@ -4076,9 +4103,11 @@ WhereInfo *sqlite3WhereBegin(
assert( isOptimal || (sCost.used&notReady)==0 );
if( (sCost.used&notReady)==0
&& (j==iFrom || sCost.rCost<bestPlan.rCost
|| (sCost.rCost==bestPlan.rCost && sCost.nRow<bestPlan.nRow))
&& (bestJ<0 || sCost.rCost<bestPlan.rCost
|| (sCost.rCost<=bestPlan.rCost && sCost.nRow<bestPlan.nRow))
){
WHERETRACE(("... best so far with cost=%g and nRow=%g\n",
sCost.rCost, sCost.nRow));
bestPlan = sCost;
bestJ = j;
}

4
test/select2.test
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@@ -153,12 +153,12 @@ do_test select2-4.1 {
do_test select2-4.2 {
execsql {
INSERT INTO bb VALUES(0);
SELECT * FROM aa, bb WHERE b;
SELECT * FROM aa CROSS JOIN bb WHERE b;
}
} {1 2 1 4 3 2 3 4}
do_test select2-4.3 {
execsql {
SELECT * FROM aa, bb WHERE NOT b;
SELECT * FROM aa CROSS JOIN bb WHERE NOT b;
}
} {1 0 3 0}
do_test select2-4.4 {

2
test/triggerA.test
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@@ -77,7 +77,7 @@ do_test triggerA-1.5 {
do_test triggerA-1.6 {
db eval {
CREATE VIEW v5 AS SELECT x, b FROM t1, t2 WHERE y=c;
SELECT * FROM v5;
SELECT * FROM v5 ORDER BY x DESC;
}
} {10 1003 9 904 8 805 7 705 6 603 5 504 4 404 3 305 2 203 1 103}

4
test/where3.test
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@@ -199,13 +199,13 @@ do_test where3-2.5 {
WHERE cpk=ax AND bpk=cx
}
} {tA {} tC * tB * tD *}
do_test where3-2.5 {
do_test where3-2.6 {
queryplan {
SELECT * FROM tA, tB, tC LEFT JOIN tD ON dpk=cx
WHERE bpk=cx AND apk=bx
}
} {tC {} tB * tA * tD *}
do_test where3-2.6 {
do_test where3-2.7 {
queryplan {
SELECT * FROM tA, tB, tC LEFT JOIN tD ON dpk=cx
WHERE cpk=bx AND apk=cx

10
test/where7.test
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@@ -90,12 +90,10 @@ do_test where7-1.9 {
}
} {2 4 5 scan 0 sort 0}
do_test where7-1.10 {
breakpoint
count_steps {
SELECT a FROM t1 WHERE (b=3 OR c>=10 OR c=4 OR b>10)
}
} {2 4 5 scan 0 sort 0}
breakpoint
do_test where7-1.11 {
count_steps {
SELECT a FROM t1 WHERE (d=5 AND b=3) OR c==100 ORDER BY a;
@@ -106,13 +104,7 @@ do_test where7-1.12 {
SELECT a FROM t1 WHERE (b BETWEEN 2 AND 4) OR c=100 ORDER BY a
}
} {1 2 3 5 scan 0 sort 1}
do_test where7-1.13.1 {
count_steps {
SELECT a FROM t1 WHERE (b BETWEEN 0 AND 2) OR (c BETWEEN 9 AND 999)
ORDER BY a DESC
}
} {5 4 1 scan 4 sort 0}
do_test where7-1.13.2 {
do_test where7-1.13 {
count_steps {
SELECT a FROM t1 WHERE (b BETWEEN 0 AND 2) OR (c BETWEEN 9 AND 999)
ORDER BY +a DESC

3
test/where8.test
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@@ -286,8 +286,9 @@ do_test where8-3.15 {
SELECT c FROM t1, t2 WHERE a BETWEEN 1 AND 2 OR a = (
SELECT sum(e IS NULL) FROM t2 AS inner WHERE t2.d>inner.d
)
ORDER BY c
}
} {I II I II I II I II I II I II III I II III I II III I II III I II III 9 0}
} {I I I I I I I I I I II II II II II II II II II II III III III III III 9 1}
#-----------------------------------------------------------------------
# The following tests - where8-4.* - verify that adding or removing