mirrors/sqlite
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Change the query planner to do a better job of estimating the number rows

Browse Source 
selected by a BETWEEN operator using STAT4 when both upper and lower bounds
are contained within the same sample.

FossilOrigin-Name: 2d36be5d9a1cdd4fd2d54fc4eeece32a81cbacc1
This commit is contained in:
drh 2014-11-05 19:26:12 +00:00
parent 6b5631e02f
commit 6d3f91d040
4 changed files with 33 additions and 25 deletions

14
manifest

@ -1,5 +1,5 @@
C Make\ssure\sthat\sNULL\sresults\sfrom\sOP_Column\sare\sfully\sand\scompletely\sNULL\nand\sdo\snot\shave\sthe\sMEM_Ephem\sbit\sset.\s\sFix\sfor\sticket\s[094d39a4c95ee4].
D 2014-11-05T15:57:39.984
C Change\sthe\squery\splanner\sto\sdo\sa\sbetter\sjob\sof\sestimating\sthe\snumber\srows\nselected\sby\sa\sBETWEEN\soperator\susing\sSTAT4\swhen\sboth\supper\sand\slower\sbounds\nare\scontained\swithin\sthe\ssame\ssample.
D 2014-11-05T19:26:12.741
F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
F Makefile.in cf57f673d77606ab0f2d9627ca52a9ba1464146a
F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@ -302,7 +302,7 @@ F src/vtab.c 2a30791bbd7926b589401bd09c3abb33de563793
F src/wal.c 825c948066c7604a07d56e67958cdab210749016
F src/wal.h df01efe09c5cb8c8e391ff1715cca294f89668a4
F src/walker.c c253b95b4ee44b21c406e2a1052636c31ea27804
F src/where.c 240961041f35862ebcafd260587c79a1ab7347f8
F src/where.c 2c2081c546c90227577c502765611555503ce3f7
F src/whereInt.h d3633e9b592103241b74b0ec76185f3e5b8b62e0
F test/8_3_names.test ebbb5cd36741350040fd28b432ceadf495be25b2
F test/aggerror.test a867e273ef9e3d7919f03ef4f0e8c0d2767944f2
@ -321,7 +321,7 @@ F test/analyze4.test eff2df19b8dd84529966420f29ea52edc6b56213
F test/analyze5.test 765c4e284aa69ca172772aa940946f55629bc8c4
F test/analyze6.test f1c552ce39cca4ec922a7e4e0e5d0203d6b3281f
F test/analyze7.test bb1409afc9e8629e414387ef048b8e0e3e0bdc4f
F test/analyze8.test 093d15c1c888eed5034304a98c992f7360130b88
F test/analyze8.test c05a461d0a6b05991106467d0c47480f2e709c82
F test/analyze9.test 72795c8113604b5dcd47a1498a61d6d7fb5d041a
F test/analyzeA.test 3335697f6700c7052295cfd0067fc5b2aacddf9a
F test/analyzeB.test 8bf35ee0a548aea831bf56762cb8e7fdb1db083d
@ -1211,7 +1211,7 @@ F tool/vdbe_profile.tcl 67746953071a9f8f2f668b73fe899074e2c6d8c1
F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
F tool/warnings.sh 0abfd78ceb09b7f7c27c688c8e3fe93268a13b32
F tool/win/sqlite.vsix deb315d026cc8400325c5863eef847784a219a2f
P 948d6e5d07bc14b6de32ec2144c716a5532f894c
R 4628888308aa60120db393287d665a20
P 42705fd7d892c4fdfb95fbbb468c99569beece25
R b31ea7cd782cb3cc21bda8e8c039f16c
U drh
Z e07070b00a71f6116b6f23e15e08fb5e
Z 7c6a788d1b7b1ae57295ef90b3d9da88

2
manifest.uuid

@ -1 +1 @@
42705fd7d892c4fdfb95fbbb468c99569beece25
2d36be5d9a1cdd4fd2d54fc4eeece32a81cbacc1

34
src/where.c

@ -1897,7 +1897,6 @@ static int vtabBestIndex(Parse *pParse, Table *pTab, sqlite3_index_info *p){
}
#endif /* !defined(SQLITE_OMIT_VIRTUALTABLE) */
#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
/*
** Estimate the location of a particular key among all keys in an
@ -1906,9 +1905,10 @@ static int vtabBestIndex(Parse *pParse, Table *pTab, sqlite3_index_info *p){
** aStat[0] Est. number of rows less than pVal
** aStat[1] Est. number of rows equal to pVal
**
** Return SQLITE_OK on success.
** Return the index of the sample that is the smallest sample that
** is greater than or equal to pRec.
*/
static void whereKeyStats(
static int whereKeyStats(
Parse *pParse, /* Database connection */
Index *pIdx, /* Index to consider domain of */
UnpackedRecord *pRec, /* Vector of values to consider */
@ -1990,6 +1990,7 @@ static void whereKeyStats(
}
aStat[0] = iLower + iGap;
}
return i;
}
#endif /* SQLITE_ENABLE_STAT3_OR_STAT4 */
@ -2140,7 +2141,7 @@ static int whereRangeSkipScanEst(
** If either of the upper or lower bound is not present, then NULL is passed in
** place of the corresponding WhereTerm.
**
** The value in (pBuilder->pNew->u.btree.nEq) is the index of the index
** The value in (pBuilder->pNew->u.btree.nEq) is the number of the index
** column subject to the range constraint. Or, equivalently, the number of
** equality constraints optimized by the proposed index scan. For example,
** assuming index p is on t1(a, b), and the SQL query is:
@ -2156,7 +2157,7 @@ static int whereRangeSkipScanEst(
**
** When this function is called, *pnOut is set to the sqlite3LogEst() of the
** number of rows that the index scan is expected to visit without
** considering the range constraints. If nEq is 0, this is the number of
** considering the range constraints. If nEq is 0, then *pnOut is the number of
** rows in the index. Assuming no error occurs, *pnOut is adjusted (reduced)
** to account for the range constraints pLower and pUpper.
**
@ -2180,9 +2181,7 @@ static int whereRangeScanEst(
Index *p = pLoop->u.btree.pIndex;
int nEq = pLoop->u.btree.nEq;
if( p->nSample>0
&& nEq<p->nSampleCol
){
if( p->nSample>0 && nEq<p->nSampleCol ){
if( nEq==pBuilder->nRecValid ){
UnpackedRecord *pRec = pBuilder->pRec;
tRowcnt a[2];
@ -2198,15 +2197,19 @@ static int whereRangeScanEst(
** is not a simple variable or literal value), the lower bound of the
** range is $P. Due to a quirk in the way whereKeyStats() works, even
** if $L is available, whereKeyStats() is called for both ($P) and
** ($P:$L) and the larger of the two returned values used.
** ($P:$L) and the larger of the two returned values is used.
**
** Similarly, iUpper is to be set to the estimate of the number of rows
** less than the upper bound of the range query. Where the upper bound
** is either ($P) or ($P:$U). Again, even if $U is available, both values
** of iUpper are requested of whereKeyStats() and the smaller used.
**
** The number of rows between the two bounds is then just iUpper-iLower.
*/
tRowcnt iLower;
tRowcnt iUpper;
tRowcnt iLower; /* Rows less than the lower bound */
tRowcnt iUpper; /* Rows less than the upper bound */
int iLwrIdx = -2; /* aSample[] for the lower bound */
int iUprIdx = -1; /* aSample[] for the upper bound */
if( pRec ){
testcase( pRec->nField!=pBuilder->nRecValid );
@ -2244,7 +2247,7 @@ static int whereRangeScanEst(
rc = sqlite3Stat4ProbeSetValue(pParse, p, &pRec, pExpr, aff, nEq, &bOk);
if( rc==SQLITE_OK && bOk ){
tRowcnt iNew;
whereKeyStats(pParse, p, pRec, 0, a);
iLwrIdx = whereKeyStats(pParse, p, pRec, 0, a);
iNew = a[0] + ((pLower->eOperator & (WO_GT|WO_LE)) ? a[1] : 0);
if( iNew>iLower ) iLower = iNew;
nOut--;
@ -2259,7 +2262,7 @@ static int whereRangeScanEst(
rc = sqlite3Stat4ProbeSetValue(pParse, p, &pRec, pExpr, aff, nEq, &bOk);
if( rc==SQLITE_OK && bOk ){
tRowcnt iNew;
whereKeyStats(pParse, p, pRec, 1, a);
iUprIdx = whereKeyStats(pParse, p, pRec, 1, a);
iNew = a[0] + ((pUpper->eOperator & (WO_GT|WO_LE)) ? a[1] : 0);
if( iNew<iUpper ) iUpper = iNew;
nOut--;
@ -2271,6 +2274,11 @@ static int whereRangeScanEst(
if( rc==SQLITE_OK ){
if( iUpper>iLower ){
nNew = sqlite3LogEst(iUpper - iLower);
/* TUNING: If both iUpper and iLower are derived from the same
** sample, then assume they are 4x more selective. This brings
** the estimated selectivity more in line with what it would be
** if estimated without the use of STAT3/4 tables. */
if( iLwrIdx==iUprIdx ) nNew -= 20; assert( 20==sqlite3LogEst(4) );
}else{
nNew = 10; assert( 10==sqlite3LogEst(2) );
}

8
test/analyze8.test

@ -86,23 +86,23 @@ do_test 2.1 {
# range.
#
# Test 3.2 is a little unstable. It depends on the planner estimating
# that (b BETWEEN 50 AND 54) will match more rows than (c BETWEEN
# that (b BETWEEN 30 AND 34) will match more rows than (c BETWEEN
# 800000 AND 900000). Which is a pretty close call (50 vs. 32), so
# the planner could get it wrong with an unlucky set of samples. This
# case happens to work, but others ("b BETWEEN 40 AND 44" for example)
# will fail.
#
do_execsql_test 3.0 {
SELECT count(*) FROM t1 WHERE b BETWEEN 50 AND 54;
SELECT count(*) FROM t1 WHERE b BETWEEN 30 AND 34;
SELECT count(*) FROM t1 WHERE c BETWEEN 0 AND 100000;
SELECT count(*) FROM t1 WHERE c BETWEEN 800000 AND 900000;
} {50 376 32}
do_test 3.1 {
eqp {SELECT * FROM t1 WHERE b BETWEEN 50 AND 54 AND c BETWEEN 0 AND 100000}
eqp {SELECT * FROM t1 WHERE b BETWEEN 30 AND 34 AND c BETWEEN 0 AND 100000}
} {0 0 0 {SEARCH TABLE t1 USING INDEX t1b (b>? AND b<?)}}
do_test 3.2 {
eqp {SELECT * FROM t1
WHERE b BETWEEN 50 AND 54 AND c BETWEEN 800000 AND 900000}
WHERE b BETWEEN 30 AND 34 AND c BETWEEN 800000 AND 900000}
} {0 0 0 {SEARCH TABLE t1 USING INDEX t1c (c>? AND c<?)}}
do_test 3.3 {
eqp {SELECT * FROM t1 WHERE a=100 AND c BETWEEN 0 AND 100000}