/ Check-in [08833dda]
Login

Many hyperlinks are disabled.
Use anonymous login to enable hyperlinks.

Overview
Comment:Do a more thorough job of cleaning traces of the strength-reduced LEFT JOIN.
Downloads: Tarball | ZIP archive | SQL archive
Timelines: family | ancestors | descendants | both | join-strength-reduction
Files: files | file ages | folders
SHA3-256: 08833dda3a25965cc509d0244d7cd68bdb2306351ca52862f347e1efe5db4508
User & Date: drh 2018-03-20 22:52:27
Original Comment: Do a more thorough job of cleaning erasing traces of the strength-reduced LEFT JOIN.
Context
2018-03-21
01:59
Relax LEFT-JOIN restrictions on the push-down optimization. Closed-Leaf check-in: b5d3dd8c user: drh tags: join-strength-reduction
2018-03-20
22:52
Do a more thorough job of cleaning traces of the strength-reduced LEFT JOIN. check-in: 08833dda user: drh tags: join-strength-reduction
21:16
If terms of the WHERE clause require that the right table in a LEFT JOIN not be a null row, then simplify the LEFT JOIN into an ordinary JOIN. check-in: 5b7abecc user: drh tags: join-strength-reduction
Changes
Hide Diffs Unified Diffs Show Whitespace Changes Patch

Changes to src/select.c.

5211
5212
5213
5214
5215
5216
5217
5218
5219
5220
5221
5222
5223
5224
5225
    */
    if( (pItem->fg.jointype & JT_LEFT)!=0
     && sqlite3ExprImpliesNonNullRow(p->pWhere, pItem->iCursor)
     && OptimizationEnabled(db, SQLITE_SimplifyJoin)
    ){
      SELECTTRACE(0x100,pParse,p,
                ("LEFT-JOIN simplifies to JOIN on term %d\n",i));
      pItem->fg.jointype &= ~JT_LEFT;
      unsetJoinExpr(p->pWhere, pItem->iCursor);
    }

    /* No futher action if this term of the FROM clause is no a subquery */
    if( pSub==0 ) continue;

    /* Catch mismatch in the declared columns of a view and the number of







|







5211
5212
5213
5214
5215
5216
5217
5218
5219
5220
5221
5222
5223
5224
5225
    */
    if( (pItem->fg.jointype & JT_LEFT)!=0
     && sqlite3ExprImpliesNonNullRow(p->pWhere, pItem->iCursor)
     && OptimizationEnabled(db, SQLITE_SimplifyJoin)
    ){
      SELECTTRACE(0x100,pParse,p,
                ("LEFT-JOIN simplifies to JOIN on term %d\n",i));
      pItem->fg.jointype &= ~(JT_LEFT|JT_OUTER);
      unsetJoinExpr(p->pWhere, pItem->iCursor);
    }

    /* No futher action if this term of the FROM clause is no a subquery */
    if( pSub==0 ) continue;

    /* Catch mismatch in the declared columns of a view and the number of

Changes to test/cursorhint2.test.

132
133
134
135
136
137
138



139
140
141
142
143
144
145
146
147
...
151
152
153
154
155
156
157
158

159
160
161
162
163
164
165
...
170
171
172
173
174
175
176

177
178
179
180
181
182
183
184

do_extract_hints_test 2.5 {
  SELECT * FROM x1 LEFT JOIN x2 ON (a=x) WHERE 1 = coalesce(b, 1)
} {
  x2 {EQ(c0,r[2])}
}




do_extract_hints_test 2.6 {
  SELECT * FROM x1 LEFT JOIN x2 ON (a=x) WHERE 0 = (b IS NOT NULL)
} {
  x2 {EQ(c0,r[2])}
}

do_extract_hints_test 2.7 {
  SELECT * FROM x1 LEFT JOIN x2 ON (a=x) WHERE 0 = (b IS NOT +NULL)
} {
................................................................................
do_extract_hints_test 2.8 {
  SELECT * FROM x1 LEFT JOIN x2 ON (a=x) WHERE b IS NOT +NULL
} {
  x2 {EQ(c0,r[2])}
}

do_extract_hints_test 2.9 {
  SELECT * FROM x1 LEFT JOIN x2 ON (a=x) WHERE CASE b WHEN 0 THEN 0 ELSE 1 END;

} {
  x2 {EQ(c0,r[2])}
}

do_extract_hints_test 2.10 {
  SELECT * FROM x1 LEFT JOIN x2 ON (a=x) WHERE x2.b = 32+32
} {
................................................................................
  # This test only works using the built-in LIKE, not the ICU LIKE extension.
  do_extract_hints_test 2.11 {
    SELECT * FROM x1 LEFT JOIN x2 ON (a=x) WHERE x2.b LIKE 'abc%'
  } {
    x2 {AND(expr,EQ(c0,r[2]))}
  }
}


do_extract_hints_test 2.12 {
  SELECT * FROM x1 LEFT JOIN x2 ON (a=x) WHERE coalesce(x2.b, 1)
} {
  x2 {EQ(c0,r[2])}
}

finish_test







>
>
>
|
|







 







|
>







 







>








132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
...
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
...
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189

do_extract_hints_test 2.5 {
  SELECT * FROM x1 LEFT JOIN x2 ON (a=x) WHERE 1 = coalesce(b, 1)
} {
  x2 {EQ(c0,r[2])}
}

if {0} {
  # These tests no longer work due to the LEFT-JOIN strength reduction
  # optimization
  do_extract_hints_test 2.6 {
    SELECT * FROM x1 CROSS JOIN x2 ON (a=x) WHERE 0 = (b IS NOT NULL)
  } {
    x2 {EQ(c0,r[2])}
  }
  
  do_extract_hints_test 2.7 {
    SELECT * FROM x1 LEFT JOIN x2 ON (a=x) WHERE 0 = (b IS NOT +NULL)
  } {
................................................................................
  do_extract_hints_test 2.8 {
    SELECT * FROM x1 LEFT JOIN x2 ON (a=x) WHERE b IS NOT +NULL
  } {
    x2 {EQ(c0,r[2])}
  }
  
  do_extract_hints_test 2.9 {
    SELECT * FROM x1 LEFT JOIN x2 ON (a=x)
      WHERE CASE b WHEN 0 THEN 0 ELSE 1 END;
  } {
    x2 {EQ(c0,r[2])}
  }
  
  do_extract_hints_test 2.10 {
    SELECT * FROM x1 LEFT JOIN x2 ON (a=x) WHERE x2.b = 32+32
  } {
................................................................................
    # This test only works using the built-in LIKE, not the ICU LIKE extension.
    do_extract_hints_test 2.11 {
      SELECT * FROM x1 LEFT JOIN x2 ON (a=x) WHERE x2.b LIKE 'abc%'
    } {
      x2 {AND(expr,EQ(c0,r[2]))}
    }
  }
}
  
do_extract_hints_test 2.12 {
  SELECT * FROM x1 LEFT JOIN x2 ON (a=x) WHERE coalesce(x2.b, 1)
} {
  x2 {EQ(c0,r[2])}
}

finish_test