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Overview
Comment:Adjust the output row estimating logic when using STAT2.
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SHA1: c8ba8855d8e93cd1e7dbbc9398a5f850fed5a382
User & Date: drh 2011-08-03 01:07:25.236
Context
2011-08-05
01:09
Allow the sqlite_stat2 table to contain a number of samples other than the default of 10. (check-in: b9d41c3490 user: drh tags: query-planner-tweaks)
2011-08-03
01:07
Adjust the output row estimating logic when using STAT2. (check-in: c8ba8855d8 user: drh tags: query-planner-tweaks)
2011-08-02
20:14
Exclude the 8_3_names.test script from the inmemory_journal permutation. (check-in: 78fc94c8d1 user: drh tags: trunk)
Changes
Unified Diff Ignore Whitespace Patch
Changes to src/sqliteInt.h.
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#endif

/*
** The number of samples of an index that SQLite takes in order to 
** construct a histogram of the table content when running ANALYZE
** and with SQLITE_ENABLE_STAT2
*/

#define SQLITE_INDEX_SAMPLES 10


/*
** The following macros are used to cast pointers to integers and
** integers to pointers.  The way you do this varies from one compiler
** to the next, so we have developed the following set of #if statements
** to generate appropriate macros for a wide range of compilers.
**








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#endif

/*
** The number of samples of an index that SQLite takes in order to 
** construct a histogram of the table content when running ANALYZE
** and with SQLITE_ENABLE_STAT2
*/
#ifndef SQLITE_INDEX_SAMPLES
# define SQLITE_INDEX_SAMPLES 10
#endif

/*
** The following macros are used to cast pointers to integers and
** integers to pointers.  The way you do this varies from one compiler
** to the next, so we have developed the following set of #if statements
** to generate appropriate macros for a wide range of compilers.
**
︙︙
Changes to src/where.c.
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  if( pRhs==0 ) return SQLITE_NOTFOUND;
  rc = whereRangeRegion(pParse, p, pRhs, 0, &iLower);
  if( rc ) goto whereEqualScanEst_cancel;
  rc = whereRangeRegion(pParse, p, pRhs, 1, &iUpper);
  if( rc ) goto whereEqualScanEst_cancel;
  WHERETRACE(("equality scan regions: %d..%d\n", iLower, iUpper));
  if( iLower>=iUpper ){
    nRowEst = p->aiRowEst[0]/(SQLITE_INDEX_SAMPLES*2);
    if( nRowEst<*pnRow ) *pnRow = nRowEst;
  }else{
    nRowEst = (iUpper-iLower)*p->aiRowEst[0]/SQLITE_INDEX_SAMPLES;
    *pnRow = nRowEst;
  }

whereEqualScanEst_cancel:








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  if( pRhs==0 ) return SQLITE_NOTFOUND;
  rc = whereRangeRegion(pParse, p, pRhs, 0, &iLower);
  if( rc ) goto whereEqualScanEst_cancel;
  rc = whereRangeRegion(pParse, p, pRhs, 1, &iUpper);
  if( rc ) goto whereEqualScanEst_cancel;
  WHERETRACE(("equality scan regions: %d..%d\n", iLower, iUpper));
  if( iLower>=iUpper ){
    nRowEst = p->aiRowEst[0]/(SQLITE_INDEX_SAMPLES*3);
    if( nRowEst<*pnRow ) *pnRow = nRowEst;
  }else{
    nRowEst = (iUpper-iLower)*p->aiRowEst[0]/SQLITE_INDEX_SAMPLES;
    *pnRow = nRowEst;
  }

whereEqualScanEst_cancel:
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    for(i=nSpan=0; i<=SQLITE_INDEX_SAMPLES; i++){
      if( aSpan[i] ){
        nSpan++;
      }else if( aSingle[i] ){
        nSingle++;
      }
    }
    nRowEst = (nSpan*2+nSingle)*p->aiRowEst[0]/(2*SQLITE_INDEX_SAMPLES)
               + nNotFound*p->aiRowEst[1];
    if( nRowEst > p->aiRowEst[0] ) nRowEst = p->aiRowEst[0];
    *pnRow = nRowEst;
    WHERETRACE(("IN row estimate: nSpan=%d, nSingle=%d, nNotFound=%d, est=%g\n",
                 nSpan, nSingle, nNotFound, nRowEst));
  }
  sqlite3ValueFree(pVal);








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    for(i=nSpan=0; i<=SQLITE_INDEX_SAMPLES; i++){
      if( aSpan[i] ){
        nSpan++;
      }else if( aSingle[i] ){
        nSingle++;
      }
    }
    nRowEst = (nSpan*3+nSingle)*p->aiRowEst[0]/(3*SQLITE_INDEX_SAMPLES)
               + nNotFound*p->aiRowEst[1];
    if( nRowEst > p->aiRowEst[0] ) nRowEst = p->aiRowEst[0];
    *pnRow = nRowEst;
    WHERETRACE(("IN row estimate: nSpan=%d, nSingle=%d, nNotFound=%d, est=%g\n",
                 nSpan, nSingle, nNotFound, nRowEst));
  }
  sqlite3ValueFree(pVal);
︙︙
Changes to test/analyze5.test.
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   47  {z>=-100 AND z<=0.0}  t1z  400
   48  {z>=-100 AND z<0.0}   t1z   50
   49  {z>=-100 AND z<=1.0}  t1z  700
   50  {z>=-100 AND z<2.0}   t1z  700
   51  {z>=-100 AND z<=2.0}  t1z  900
   52  {z>=-100 AND z<3.0}   t1z  900
  
  101  {z=-1}                t1z   50
  102  {z=0}                 t1z  400
  103  {z=1}                 t1z  300
  104  {z=2}                 t1z  200
  105  {z=3}                 t1z  100
  106  {z=4}                 t1z   50
  107  {z=-10.0}             t1z   50
  108  {z=0.0}               t1z  400
  109  {z=1.0}               t1z  300
  110  {z=2.0}               t1z  200
  111  {z=3.0}               t1z  100
  112  {z=4.0}               t1z   50
  113  {z=1.5}               t1z   50
  114  {z=2.5}               t1z   50
  
  201  {z IN (-1)}           t1z   50
  202  {z IN (0)}            t1z  400
  203  {z IN (1)}            t1z  300
  204  {z IN (2)}            t1z  200
  205  {z IN (3)}            t1z  100
  206  {z IN (4)}            t1z   50
  207  {z IN (0.5)}          t1z   50
  208  {z IN (0,1)}          t1z  700
  209  {z IN (0,1,2)}        t1z  900
  210  {z IN (0,1,2,3)}      {}   100
  211  {z IN (0,1,2,3,4,5)}  {}   100
  212  {z IN (1,2)}          t1z  500
  213  {z IN (2,3)}          t1z  300
  214  {z=3 OR z=2}          t1z  300
  215  {z IN (-1,3)}         t1z  150
  216  {z=-1 OR z=3}         t1z  150

  300  {y=0}                 {}   100
  301  {y=1}                 t1y   50
  302  {y=0.1}               t1y   50

  400  {x IS NULL}           t1x  400

} {
  # Verify that the expected index is used with the expected row count
  do_test analyze5-1.${testid}a {
    set x [lindex [eqp "SELECT * FROM t1 WHERE $where"] 3]








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   47  {z>=-100 AND z<=0.0}  t1z  400
   48  {z>=-100 AND z<0.0}   t1z   50
   49  {z>=-100 AND z<=1.0}  t1z  700
   50  {z>=-100 AND z<2.0}   t1z  700
   51  {z>=-100 AND z<=2.0}  t1z  900
   52  {z>=-100 AND z<3.0}   t1z  900
  
  101  {z=-1}                t1z   33
  102  {z=0}                 t1z  400
  103  {z=1}                 t1z  300
  104  {z=2}                 t1z  200
  105  {z=3}                 t1z  100
  106  {z=4}                 t1z   33
  107  {z=-10.0}             t1z   33
  108  {z=0.0}               t1z  400
  109  {z=1.0}               t1z  300
  110  {z=2.0}               t1z  200
  111  {z=3.0}               t1z  100
  112  {z=4.0}               t1z   33
  113  {z=1.5}               t1z   33
  114  {z=2.5}               t1z   33
  
  201  {z IN (-1)}           t1z   33
  202  {z IN (0)}            t1z  400
  203  {z IN (1)}            t1z  300
  204  {z IN (2)}            t1z  200
  205  {z IN (3)}            t1z  100
  206  {z IN (4)}            t1z   33
  207  {z IN (0.5)}          t1z   33
  208  {z IN (0,1)}          t1z  700
  209  {z IN (0,1,2)}        t1z  900
  210  {z IN (0,1,2,3)}      {}   100
  211  {z IN (0,1,2,3,4,5)}  {}   100
  212  {z IN (1,2)}          t1z  500
  213  {z IN (2,3)}          t1z  300
  214  {z=3 OR z=2}          t1z  300
  215  {z IN (-1,3)}         t1z  133
  216  {z=-1 OR z=3}         t1z  133

  300  {y=0}                 {}   100
  301  {y=1}                 t1y   33
  302  {y=0.1}               t1y   33

  400  {x IS NULL}           t1x  400

} {
  # Verify that the expected index is used with the expected row count
  do_test analyze5-1.${testid}a {
    set x [lindex [eqp "SELECT * FROM t1 WHERE $where"] 3]
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   ANALYZE;
}

# Verify that range queries generate the correct row count estimates
#
foreach {testid where index rows} {
  500  {x IS NULL AND u='charlie'}         t1u  20
  501  {x=1 AND u='charlie'}               t1x   5
  502  {x IS NULL}                          {} 100
  503  {x=1}                               t1x  50
  504  {x IS NOT NULL}                     t1x  25
  505  {+x IS NOT NULL}                     {} 500
  506  {upper(x) IS NOT NULL}               {} 500

} {
  # Verify that the expected index is used with the expected row count
  do_test analyze5-1.${testid}a {








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   ANALYZE;
}

# Verify that range queries generate the correct row count estimates
#
foreach {testid where index rows} {
  500  {x IS NULL AND u='charlie'}         t1u  20
  501  {x=1 AND u='charlie'}               t1x   3
  502  {x IS NULL}                          {} 100
  503  {x=1}                               t1x  33
  504  {x IS NOT NULL}                     t1x  25
  505  {+x IS NOT NULL}                     {} 500
  506  {upper(x) IS NOT NULL}               {} 500

} {
  # Verify that the expected index is used with the expected row count
  do_test analyze5-1.${testid}a {
︙︙
Changes to test/analyze7.test.
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    execsql {EXPLAIN QUERY PLAN SELECT * FROM t1 WHERE c=2;}
  } {0 0 0 {SEARCH TABLE t1 USING INDEX t1cd (c=?) (~86 rows)}}
}
do_test analyze7-3.3 {
  execsql {EXPLAIN QUERY PLAN SELECT * FROM t1 WHERE a=123 AND b=123}
} {0 0 0 {SEARCH TABLE t1 USING INDEX t1a (a=?) (~1 rows)}}
do_test analyze7-3.4 {
  execsql {EXPLAIN QUERY PLAN SELECT * FROM t1 WHERE c=123 AND b=123}


} {0 0 0 {SEARCH TABLE t1 USING INDEX t1b (b=?) (~2 rows)}}
do_test analyze7-3.5 {
  execsql {EXPLAIN QUERY PLAN SELECT * FROM t1 WHERE a=123 AND c=123}
} {0 0 0 {SEARCH TABLE t1 USING INDEX t1a (a=?) (~1 rows)}}
do_test analyze7-3.6 {
  execsql {EXPLAIN QUERY PLAN SELECT * FROM t1 WHERE c=123 AND d=123 AND b=123}
} {0 0 0 {SEARCH TABLE t1 USING INDEX t1cd (c=? AND d=?) (~1 rows)}}









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    execsql {EXPLAIN QUERY PLAN SELECT * FROM t1 WHERE c=2;}
  } {0 0 0 {SEARCH TABLE t1 USING INDEX t1cd (c=?) (~86 rows)}}
}
do_test analyze7-3.3 {
  execsql {EXPLAIN QUERY PLAN SELECT * FROM t1 WHERE a=123 AND b=123}
} {0 0 0 {SEARCH TABLE t1 USING INDEX t1a (a=?) (~1 rows)}}
do_test analyze7-3.4 {
  set x [execsql {EXPLAIN QUERY PLAN SELECT * FROM t1 WHERE c=123 AND b=123}]
  regsub -all {[bcd]+} $x {x} x
  set x
} {0 0 0 {SEARCH TABLE t1 USING INDEX t1x (x=?) (~2 rows)}}
do_test analyze7-3.5 {
  execsql {EXPLAIN QUERY PLAN SELECT * FROM t1 WHERE a=123 AND c=123}
} {0 0 0 {SEARCH TABLE t1 USING INDEX t1a (a=?) (~1 rows)}}
do_test analyze7-3.6 {
  execsql {EXPLAIN QUERY PLAN SELECT * FROM t1 WHERE c=123 AND d=123 AND b=123}
} {0 0 0 {SEARCH TABLE t1 USING INDEX t1cd (c=? AND d=?) (~1 rows)}}
︙︙