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Changes On Branch cursor-hints
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Changes In Branch cursor-hints Excluding Merge-Ins

This is equivalent to a diff from 0b1579ca to 7455d932

2018-12-14
20:28
Add a missing OP_ColumnsUsed opcode to code for expressions like "? IN (SELECT ...)" in cases where expression can use an index that may contain NULL values. (Backported fix from version 3.14.0). (Leaf check-in: 11368e67 user: drh tags: branch-3.8.9)
2016-06-20
17:25
For a table on the rhs of a LEFT JOIN operator, do not include terms like "IS NULL" from the WHERE clause in the cursor-hint. These may be false for rows that the cursor would otherwise visit, but true for a row of all NULL values generated by the LEFT JOIN. (check-in: 913e5956 user: dan tags: trunk)
17:22
Allow LIKE operators that appear in a WHERE clause to be included in the cursor-hint for a cursor on the rhs of a LEFT JOIN. (Closed-Leaf check-in: 7455d932 user: dan tags: cursor-hints)
2016-06-17
19:27
Include WHERE terms in the cursor-hint passed to a cursor opened for the rhs of a LEFT JOIN iff we can be sure that those terms will not evaluate to true if the LEFT JOIN generates a row of NULLs. (check-in: 998095ab user: dan tags: cursor-hints)
14:33
If a table is on the rhs of a LEFT JOIN, include only terms from the joins ON(...) clause in the cursor-hint passed via OP_CursorHint. (check-in: 2a2346b0 user: dan tags: cursor-hints)
13:01
Add the json_quote() function to the JSON1 extension. (Closed-Leaf check-in: 2c3714ae user: drh tags: json_quote)
2016-06-16
17:14
Add a missing OP_ColumnsUsed opcode to code for expressions like "? IN (SELECT ...)" in cases where expression can use an index that may contain NULL values. (check-in: 0b1579ca user: dan tags: trunk)
11:16
Fix a typo in a comment on the SrcList object. (check-in: 48b555c4 user: drh tags: trunk)

Changes to src/wherecode.c.

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   && sqlite3ColumnOfIndex(pHint->pIdx, pExpr->iColumn)<0
  ){
    pWalker->eCode = 1;
  }
  return WRC_Continue;
}


































/*
** This function is called on every node of an expression tree used as an
** argument to the OP_CursorHint instruction. If the node is a TK_COLUMN
** that accesses any table other than the one identified by
** CCurHint.iTabCur, then do the following:
**







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   && sqlite3ColumnOfIndex(pHint->pIdx, pExpr->iColumn)<0
  ){
    pWalker->eCode = 1;
  }
  return WRC_Continue;
}

/*
** Test whether or not expression pExpr, which was part of a WHERE clause,
** should be included in the cursor-hint for a table that is on the rhs
** of a LEFT JOIN. Set Walker.eCode to non-zero before returning if the 
** expression is not suitable.
**
** An expression is unsuitable if it might evaluate to non NULL even if
** a TK_COLUMN node that does affect the value of the expression is set
** to NULL. For example:
**
**   col IS NULL
**   col IS NOT NULL
**   coalesce(col, 1)
**   CASE WHEN col THEN 0 ELSE 1 END
*/
static int codeCursorHintIsOrFunction(Walker *pWalker, Expr *pExpr){
  if( pExpr->op==TK_IS 
   || pExpr->op==TK_ISNULL || pExpr->op==TK_ISNOT 
   || pExpr->op==TK_NOTNULL || pExpr->op==TK_CASE 
  ){
    pWalker->eCode = 1;
  }else if( pExpr->op==TK_FUNCTION ){
    int d1;
    char d2[3];
    if( 0==sqlite3IsLikeFunction(pWalker->pParse->db, pExpr, &d1, d2) ){
      pWalker->eCode = 1;
    }
  }

  return WRC_Continue;
}


/*
** This function is called on every node of an expression tree used as an
** argument to the OP_CursorHint instruction. If the node is a TK_COLUMN
** that accesses any table other than the one identified by
** CCurHint.iTabCur, then do the following:
**
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  return rc;
}

/*
** Insert an OP_CursorHint instruction if it is appropriate to do so.
*/
static void codeCursorHint(

  WhereInfo *pWInfo,    /* The where clause */
  WhereLevel *pLevel,   /* Which loop to provide hints for */
  WhereTerm *pEndRange  /* Hint this end-of-scan boundary term if not NULL */
){
  Parse *pParse = pWInfo->pParse;
  sqlite3 *db = pParse->db;
  Vdbe *v = pParse->pVdbe;







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  return rc;
}

/*
** Insert an OP_CursorHint instruction if it is appropriate to do so.
*/
static void codeCursorHint(
  struct SrcList_item *pTabItem,  /* FROM clause item */
  WhereInfo *pWInfo,    /* The where clause */
  WhereLevel *pLevel,   /* Which loop to provide hints for */
  WhereTerm *pEndRange  /* Hint this end-of-scan boundary term if not NULL */
){
  Parse *pParse = pWInfo->pParse;
  sqlite3 *db = pParse->db;
  Vdbe *v = pParse->pVdbe;
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  sWalker.pParse = pParse;
  sWalker.u.pCCurHint = &sHint;
  pWC = &pWInfo->sWC;
  for(i=0; i<pWC->nTerm; i++){
    pTerm = &pWC->a[i];
    if( pTerm->wtFlags & (TERM_VIRTUAL|TERM_CODED) ) continue;
    if( pTerm->prereqAll & pLevel->notReady ) continue;


































    if( ExprHasProperty(pTerm->pExpr, EP_FromJoin) ) continue;


    /* All terms in pWLoop->aLTerm[] except pEndRange are used to initialize
    ** the cursor.  These terms are not needed as hints for a pure range
    ** scan (that has no == terms) so omit them. */
    if( pLoop->u.btree.nEq==0 && pTerm!=pEndRange ){
      for(j=0; j<pLoop->nLTerm && pLoop->aLTerm[j]!=pTerm; j++){}
      if( j<pLoop->nLTerm ) continue;







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  sWalker.pParse = pParse;
  sWalker.u.pCCurHint = &sHint;
  pWC = &pWInfo->sWC;
  for(i=0; i<pWC->nTerm; i++){
    pTerm = &pWC->a[i];
    if( pTerm->wtFlags & (TERM_VIRTUAL|TERM_CODED) ) continue;
    if( pTerm->prereqAll & pLevel->notReady ) continue;

    /* Any terms specified as part of the ON(...) clause for any LEFT 
    ** JOIN for which the current table is not the rhs are omitted
    ** from the cursor-hint. 
    **
    ** If this table is the rhs of a LEFT JOIN, "IS" or "IS NULL" terms 
    ** that were specified as part of the WHERE clause must be excluded.
    ** This is to address the following:
    **
    **   SELECT ... t1 LEFT JOIN t2 ON (t1.a=t2.b) WHERE t2.c IS NULL;
    **
    ** Say there is a single row in t2 that matches (t1.a=t2.b), but its
    ** t2.c values is not NULL. If the (t2.c IS NULL) constraint is 
    ** pushed down to the cursor, this row is filtered out, causing
    ** SQLite to synthesize a row of NULL values. Which does match the
    ** WHERE clause, and so the query returns a row. Which is incorrect.
    **
    ** For the same reason, WHERE terms such as:
    **
    **   WHERE 1 = (t2.c IS NULL)
    **
    ** are also excluded. See codeCursorHintIsOrFunction() for details.
    */
    if( pTabItem->fg.jointype & JT_LEFT ){
      Expr *pExpr = pTerm->pExpr;
      if( !ExprHasProperty(pExpr, EP_FromJoin) 
       || pExpr->iRightJoinTable!=pTabItem->iCursor
      ){
        sWalker.eCode = 0;
        sWalker.xExprCallback = codeCursorHintIsOrFunction;
        sqlite3WalkExpr(&sWalker, pTerm->pExpr);
        if( sWalker.eCode ) continue;
      }
    }else{
      if( ExprHasProperty(pTerm->pExpr, EP_FromJoin) ) continue;
    }

    /* All terms in pWLoop->aLTerm[] except pEndRange are used to initialize
    ** the cursor.  These terms are not needed as hints for a pure range
    ** scan (that has no == terms) so omit them. */
    if( pLoop->u.btree.nEq==0 && pTerm!=pEndRange ){
      for(j=0; j<pLoop->nLTerm && pLoop->aLTerm[j]!=pTerm; j++){}
      if( j<pLoop->nLTerm ) continue;
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    sqlite3WalkExpr(&sWalker, pExpr);
    sqlite3VdbeAddOp4(v, OP_CursorHint, 
                      (sHint.pIdx ? sHint.iIdxCur : sHint.iTabCur), 0, 0,
                      (const char*)pExpr, P4_EXPR);
  }
}
#else
# define codeCursorHint(A,B,C)  /* No-op */
#endif /* SQLITE_ENABLE_CURSOR_HINTS */

/*
** Cursor iCur is open on an intkey b-tree (a table). Register iRowid contains
** a rowid value just read from cursor iIdxCur, open on index pIdx. This
** function generates code to do a deferred seek of cursor iCur to the 
** rowid stored in register iRowid.







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    sqlite3WalkExpr(&sWalker, pExpr);
    sqlite3VdbeAddOp4(v, OP_CursorHint, 
                      (sHint.pIdx ? sHint.iIdxCur : sHint.iTabCur), 0, 0,
                      (const char*)pExpr, P4_EXPR);
  }
}
#else
# define codeCursorHint(A,B,C,D)  /* No-op */
#endif /* SQLITE_ENABLE_CURSOR_HINTS */

/*
** Cursor iCur is open on an intkey b-tree (a table). Register iRowid contains
** a rowid value just read from cursor iIdxCur, open on index pIdx. This
** function generates code to do a deferred seek of cursor iCur to the 
** rowid stored in register iRowid.
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    if( pLoop->wsFlags & WHERE_TOP_LIMIT ) pEnd = pLoop->aLTerm[j++];
    assert( pStart!=0 || pEnd!=0 );
    if( bRev ){
      pTerm = pStart;
      pStart = pEnd;
      pEnd = pTerm;
    }
    codeCursorHint(pWInfo, pLevel, pEnd);
    if( pStart ){
      Expr *pX;             /* The expression that defines the start bound */
      int r1, rTemp;        /* Registers for holding the start boundary */

      /* The following constant maps TK_xx codes into corresponding 
      ** seek opcodes.  It depends on a particular ordering of TK_xx
      */







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    if( pLoop->wsFlags & WHERE_TOP_LIMIT ) pEnd = pLoop->aLTerm[j++];
    assert( pStart!=0 || pEnd!=0 );
    if( bRev ){
      pTerm = pStart;
      pStart = pEnd;
      pEnd = pTerm;
    }
    codeCursorHint(pTabItem, pWInfo, pLevel, pEnd);
    if( pStart ){
      Expr *pX;             /* The expression that defines the start bound */
      int r1, rTemp;        /* Registers for holding the start boundary */

      /* The following constant maps TK_xx codes into corresponding 
      ** seek opcodes.  It depends on a particular ordering of TK_xx
      */
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      SWAP(u8, bSeekPastNull, bStopAtNull);
    }

    /* Generate code to evaluate all constraint terms using == or IN
    ** and store the values of those terms in an array of registers
    ** starting at regBase.
    */
    codeCursorHint(pWInfo, pLevel, pRangeEnd);
    regBase = codeAllEqualityTerms(pParse,pLevel,bRev,nExtraReg,&zStartAff);
    assert( zStartAff==0 || sqlite3Strlen30(zStartAff)>=nEq );
    if( zStartAff ) cEndAff = zStartAff[nEq];
    addrNxt = pLevel->addrNxt;

    testcase( pRangeStart && (pRangeStart->eOperator & WO_LE)!=0 );
    testcase( pRangeStart && (pRangeStart->eOperator & WO_GE)!=0 );







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      SWAP(u8, bSeekPastNull, bStopAtNull);
    }

    /* Generate code to evaluate all constraint terms using == or IN
    ** and store the values of those terms in an array of registers
    ** starting at regBase.
    */
    codeCursorHint(pTabItem, pWInfo, pLevel, pRangeEnd);
    regBase = codeAllEqualityTerms(pParse,pLevel,bRev,nExtraReg,&zStartAff);
    assert( zStartAff==0 || sqlite3Strlen30(zStartAff)>=nEq );
    if( zStartAff ) cEndAff = zStartAff[nEq];
    addrNxt = pLevel->addrNxt;

    testcase( pRangeStart && (pRangeStart->eOperator & WO_LE)!=0 );
    testcase( pRangeStart && (pRangeStart->eOperator & WO_GE)!=0 );
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    static const u8 aStart[] = { OP_Rewind, OP_Last };
    assert( bRev==0 || bRev==1 );
    if( pTabItem->fg.isRecursive ){
      /* Tables marked isRecursive have only a single row that is stored in
      ** a pseudo-cursor.  No need to Rewind or Next such cursors. */
      pLevel->op = OP_Noop;
    }else{
      codeCursorHint(pWInfo, pLevel, 0);
      pLevel->op = aStep[bRev];
      pLevel->p1 = iCur;
      pLevel->p2 = 1 + sqlite3VdbeAddOp2(v, aStart[bRev], iCur, addrBrk);
      VdbeCoverageIf(v, bRev==0);
      VdbeCoverageIf(v, bRev!=0);
      pLevel->p5 = SQLITE_STMTSTATUS_FULLSCAN_STEP;
    }







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    static const u8 aStart[] = { OP_Rewind, OP_Last };
    assert( bRev==0 || bRev==1 );
    if( pTabItem->fg.isRecursive ){
      /* Tables marked isRecursive have only a single row that is stored in
      ** a pseudo-cursor.  No need to Rewind or Next such cursors. */
      pLevel->op = OP_Noop;
    }else{
      codeCursorHint(pTabItem, pWInfo, pLevel, 0);
      pLevel->op = aStep[bRev];
      pLevel->p1 = iCur;
      pLevel->p2 = 1 + sqlite3VdbeAddOp2(v, aStart[bRev], iCur, addrBrk);
      VdbeCoverageIf(v, bRev==0);
      VdbeCoverageIf(v, bRev!=0);
      pLevel->p5 = SQLITE_STMTSTATUS_FULLSCAN_STEP;
    }

Added test/cursorhint2.test.









































































































































































































































































































































































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# 2016 June 17
#
# The author disclaims copyright to this source code.  In place of
# a legal notice, here is a blessing:
#
#    May you do good and not evil.
#    May you find forgiveness for yourself and forgive others.
#    May you share freely, never taking more than you give.
#
#***********************************************************************
# This file implements regression tests for SQLite library. The
# focus is on testing that cursor-hints are correct for queries
# involving LEFT JOIN.
#


set testdir [file dirname $argv0]
source $testdir/tester.tcl
set ::testprefix cursorhint2

ifcapable !cursorhints {
  finish_test
  return
}

proc extract_hints {sql} {

  db eval "SELECT tbl_name, rootpage FROM sqlite_master where rootpage" {
    set lookup($rootpage) $tbl_name
  }

  set ret [list]
  db eval "EXPLAIN $sql" a {
    switch -- $a(opcode) {
      OpenRead {
        set csr($a(p1)) $lookup($a(p2))
      }
      CursorHint { 
        lappend ret $csr($a(p1)) $a(p4) 
      }
    }
  }

  set ret
}

proc do_extract_hints_test {tn sql ret} {
  uplevel [list do_test $tn [list extract_hints $sql] [list {*}$ret]]
}

do_execsql_test 1.0 {
  PRAGMA automatic_index = 0;
  CREATE TABLE t1(a, b);
  CREATE TABLE t2(c, d);
  CREATE TABLE t3(e, f);
}

do_extract_hints_test 1.1 {
  SELECT * FROM t1 WHERE a=1;
} {
  t1 EQ(c0,1)
}

do_extract_hints_test 1.2 {
  SELECT * FROM t1 CROSS JOIN t2 ON (a=c) WHERE d IS NULL;
} {
  t2 {AND(ISNULL(c1),EQ(r[1],c0))}
}

do_extract_hints_test 1.3 {
  SELECT * FROM t1 LEFT JOIN t2 ON (a=c) WHERE d IS NULL;
} {
  t2 {EQ(r[2],c0)}
}

do_extract_hints_test 1.4 {
  SELECT * FROM t1 LEFT JOIN t2 ON (a=c AND a=10) WHERE d IS NULL;
} {
  t2 {AND(EQ(r[2],c0),EQ(r[3],10))}
}

do_extract_hints_test 1.5 {
  SELECT * FROM t1 CROSS JOIN t2 ON (a=c AND a=10) WHERE d IS NULL;
} {
  t1 EQ(c0,10) t2 {AND(ISNULL(c1),EQ(r[3],c0))}
}

do_extract_hints_test 1.6 {
  SELECT * FROM t1 LEFT JOIN t2 ON (a=c) LEFT JOIN t3 ON (d=f);
} {
  t2 {EQ(r[2],c0)} t3 {EQ(r[6],c1)}
}

do_extract_hints_test 1.7 {
  SELECT * FROM t1 LEFT JOIN t2 ON (a=c AND d=e) LEFT JOIN t3 ON (d=f);
} {
  t2 {EQ(r[2],c0)} t3 {AND(EQ(r[6],c0),EQ(r[7],c1))}
}

#-------------------------------------------------------------------------
#
do_execsql_test 2.0 {
  CREATE TABLE x1(x, y);
  CREATE TABLE x2(a, b);
}

do_extract_hints_test 2.1 {
  SELECT * FROM x1 LEFT JOIN x2 ON (a=x) WHERE b IS NULL;
} {
  x2 {EQ(c0,r[2])}
}

do_extract_hints_test 2.2 {
  SELECT * FROM x1 LEFT JOIN x2 ON (a=x) WHERE b IS +NULL;
} {
  x2 {EQ(c0,r[2])}
}

do_extract_hints_test 2.3 {
  SELECT * FROM x1 LEFT JOIN x2 ON (a=x) WHERE 1 = (b IS NULL)
} {
  x2 {EQ(c0,r[2])}
}

do_extract_hints_test 2.4 {
  SELECT * FROM x1 LEFT JOIN x2 ON (a=x) WHERE 1 = coalesce(b, 1)
} {
  x2 {EQ(c0,r[2])}
}

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

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
} {
  x2 {AND(EQ(c1,ADD(32,32)),EQ(c0,r[2]))}
}

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 2.11 {
  SELECT * FROM x1 LEFT JOIN x2 ON (a=x) WHERE coalesce(x2.b, 1)
} {
  x2 {EQ(c0,r[2])}
}

finish_test

Changes to test/where3.test.

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    INSERT INTO t3 VALUES(999,'nine');
    CREATE INDEX t3i1 ON t3(x);
    
    SELECT * FROM t1, t2 LEFT JOIN t3 ON q=x WHERE p=2 AND a=q;
  }
} {222 two 2 222 {} {}}

ifcapable explain {
  do_test where3-1.1.1 {
     explain_no_trace {SELECT * FROM t1, t2 LEFT JOIN t3 ON q=x
                        WHERE p=2 AND a=q}
  } [explain_no_trace {SELECT * FROM t1, t2 LEFT JOIN t3 ON x=q
                        WHERE p=2 AND a=q}]
}








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    INSERT INTO t3 VALUES(999,'nine');
    CREATE INDEX t3i1 ON t3(x);
    
    SELECT * FROM t1, t2 LEFT JOIN t3 ON q=x WHERE p=2 AND a=q;
  }
} {222 two 2 222 {} {}}

ifcapable explain&&!cursorhints {
  do_test where3-1.1.1 {
     explain_no_trace {SELECT * FROM t1, t2 LEFT JOIN t3 ON q=x
                        WHERE p=2 AND a=q}
  } [explain_no_trace {SELECT * FROM t1, t2 LEFT JOIN t3 ON x=q
                        WHERE p=2 AND a=q}]
}

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    SELECT parent1.parent1key, child1.value, child2.value
    FROM parent1
    LEFT OUTER JOIN child1 ON child1.child1key = parent1.child1key
    INNER JOIN child2 ON child2.child2key = parent1.child2key;
  }
} {1 {Value for C1.1} {Value for C2.1} 2 {} {Value for C2.2} 3 {Value for C1.3} {Value for C2.3}}

ifcapable explain {
  do_test where3-1.2.1 {
     explain_no_trace {
       SELECT parent1.parent1key, child1.value, child2.value
       FROM parent1
       LEFT OUTER JOIN child1 ON child1.child1key = parent1.child1key
       INNER JOIN child2 ON child2.child2key = parent1.child2key;
     }







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    SELECT parent1.parent1key, child1.value, child2.value
    FROM parent1
    LEFT OUTER JOIN child1 ON child1.child1key = parent1.child1key
    INNER JOIN child2 ON child2.child2key = parent1.child2key;
  }
} {1 {Value for C1.1} {Value for C2.1} 2 {} {Value for C2.2} 3 {Value for C1.3} {Value for C2.3}}

ifcapable explain&&!cursorhints {
  do_test where3-1.2.1 {
     explain_no_trace {
       SELECT parent1.parent1key, child1.value, child2.value
       FROM parent1
       LEFT OUTER JOIN child1 ON child1.child1key = parent1.child1key
       INNER JOIN child2 ON child2.child2key = parent1.child2key;
     }