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Comment:Another test case for the planner change on this branch.
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SHA1: f2207a0691ed361061719f4dacf021a677a9d892
User & Date: dan 2015-03-16 09:21:30
Context
2015-03-16
16:28
When estimating the number of rows visited by a range scan for which the keys consist of more than one field, consider prefixes of stat4 samples as well as the full samples. This generates more accurate estimates. check-in: 3e0590de user: dan tags: trunk
09:21
Another test case for the planner change on this branch. Closed-Leaf check-in: f2207a06 user: dan tags: stat4-change
2015-03-14
18:59
When estimating the number of rows visited by a range scan for which the keys consist of more than one field, consider prefixes of stat4 samples as well as the full samples. check-in: e1caf93c user: dan tags: stat4-change
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Changes to test/analyze9.test.

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}

#-------------------------------------------------------------------------
# Check that a problem in they way stat4 data is used has been 
# resolved (see below).
#
reset_db
do_test 26.1 {
  db transaction {
    execsql { 
      CREATE TABLE t1(x, y, z);
      CREATE INDEX t1xy ON t1(x, y);
      CREATE INDEX t1z ON t1(z);
    }
    for {set i 0} {$i < 10000} {incr i} {
................................................................................
    execsql {
      UPDATE t1 SET z = rowid / 20;
      ANALYZE;
    }
  }
} {}

do_execsql_test 26.2 {
  SELECT count(*) FROM t1 WHERE x = 10000 AND y < 50;
} {49}
do_execsql_test 26.3 {
  SELECT count(*) FROM t1 WHERE z = 444;
} {20}

# The analyzer knows that any (z=?) expression matches 20 rows. So it
# will use index "t1z" if the estimate of hits for (x=10000 AND y<50)
# is greater than 20 rows.
#
................................................................................
# There should be no other samples that start with (x=10000). So it knows 
# that (x=10000 AND y<50) must match somewhere between 0 and 99 rows, but
# know more than that. Guessing less than 20 is therefore unreasonable.
#
# At one point though, due to a problem in whereKeyStats(), the planner was
# estimating that (x=10000 AND y<50) would match only 2 rows.
#
do_eqp_test 26.4 {
  SELECT * FROM t1 WHERE x = 10000 AND y < 50 AND z = 444;
} {
  0 0 0 {SEARCH TABLE t1 USING INDEX t1z (z=?)}
}





















































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}

#-------------------------------------------------------------------------
# Check that a problem in they way stat4 data is used has been 
# resolved (see below).
#
reset_db
do_test 26.1.1 {
  db transaction {
    execsql { 
      CREATE TABLE t1(x, y, z);
      CREATE INDEX t1xy ON t1(x, y);
      CREATE INDEX t1z ON t1(z);
    }
    for {set i 0} {$i < 10000} {incr i} {
................................................................................
    execsql {
      UPDATE t1 SET z = rowid / 20;
      ANALYZE;
    }
  }
} {}

do_execsql_test 26.1.2 {
  SELECT count(*) FROM t1 WHERE x = 10000 AND y < 50;
} {49}
do_execsql_test 26.1.3 {
  SELECT count(*) FROM t1 WHERE z = 444;
} {20}

# The analyzer knows that any (z=?) expression matches 20 rows. So it
# will use index "t1z" if the estimate of hits for (x=10000 AND y<50)
# is greater than 20 rows.
#
................................................................................
# There should be no other samples that start with (x=10000). So it knows 
# that (x=10000 AND y<50) must match somewhere between 0 and 99 rows, but
# know more than that. Guessing less than 20 is therefore unreasonable.
#
# At one point though, due to a problem in whereKeyStats(), the planner was
# estimating that (x=10000 AND y<50) would match only 2 rows.
#
do_eqp_test 26.1.4 {
  SELECT * FROM t1 WHERE x = 10000 AND y < 50 AND z = 444;
} {
  0 0 0 {SEARCH TABLE t1 USING INDEX t1z (z=?)}
}


# This test - 26.2.* - tests that another manifestation of the same problem
# is no longer present in the library. Assuming:
# 
#   CREATE INDEX t1xy ON t1(x, y)
#
# and that have samples for index t1xy as follows:
#
#
#   sample=('A', 70)        nEq=(100, 2)        nLt=(900, 970)
#   sample=('B', 70)        nEq=(100, 2)        nLt=(1000, 1070)    
#
# the planner should estimate that (x = 'B' AND y > 25) matches 76 rows
# (70 * 2/3 + 30). Before, due to the problem, the planner was estimating 
# that this matched 100 rows.
# 
reset_db
do_execsql_test 26.2.1 {
  BEGIN;
    CREATE TABLE t1(x, y, z);
    CREATE INDEX i1 ON t1(x, y);
    CREATE INDEX i2 ON t1(z);
  
    WITH 
    cnt(y) AS (SELECT 0 UNION ALL SELECT y+1 FROM cnt WHERE y<99),
    letters(x) AS (
      SELECT 'A' UNION SELECT 'B' UNION SELECT 'C' UNION SELECT 'D'
    )
    INSERT INTO t1(x, y) SELECT x, y FROM letters, cnt;
  
    WITH
    letters(x) AS (
      SELECT 'A' UNION SELECT 'B' UNION SELECT 'C' UNION SELECT 'D'
    )
    INSERT INTO t1(x, y) SELECT x, 70 FROM letters;
  
    WITH
    cnt(i) AS (SELECT 0 UNION ALL SELECT i+1 FROM cnt WHERE i<9999)
    INSERT INTO t1(x, y) SELECT i, i FROM cnt;
  
    UPDATE t1 SET z = (rowid / 95);
    ANALYZE;
  COMMIT;
}

do_eqp_test 26.2.2 {
  SELECT * FROM t1 WHERE x='B' AND y>25 AND z=?;
} {
  0 0 0 {SEARCH TABLE t1 USING INDEX i1 (x=? AND y>?)}
}


finish_test