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Overview
Comment:Convert expressions of the form "X IN (?)" with exactly one value on the RHS of the IN into equality tests: "X=?". Add test cases to verify that statements work correctly on this corner case. Fix for ticket [e39d032577df6942].
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SHA1:e68b427afbc82e201c64474117851aa4c9eb0c92
User & Date: drh 2014-03-20 13:26:47
References
2014-03-20
17:03
The "x IN (?)" optimization in check-ins [2ff3b25f40] and [e68b427afb] is incorrect, as demonstrated by the in4-5.1 test case in this check-in. The "COLLATE binary" that was being added to the RHS of IN was overriding the implicit collating sequence of the LHS. This change defines the EP_Generic expression node property that blocks all affinity or collating sequence information in the expression subtree and adds that property to the expression taken from RHS of the IN operator. check-in: 2ea4a9f7 user: drh tags: trunk
Context
2014-03-20
14:56
Previous check-in is not quite correct. "x IN (?)" is not exactly the same as "x==?" do to collation and affinity issues. The correct converstion should be to "x==(+? COLLATE binary)". The current check-in fixes this problem and provides test cases. Ticket [e39d032577df69] check-in: 2ff3b25f user: drh tags: trunk
13:26
Convert expressions of the form "X IN (?)" with exactly one value on the RHS of the IN into equality tests: "X=?". Add test cases to verify that statements work correctly on this corner case. Fix for ticket [e39d032577df6942]. check-in: e68b427a user: drh tags: trunk
12:17
Fix an unnecessarily obtuse use of a bitmask flag. check-in: ca314081 user: drh tags: trunk
Changes
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Changes to src/parse.y.

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      **      expr1 NOT IN ()
      **
      ** simplify to constants 0 (false) and 1 (true), respectively,
      ** regardless of the value of expr1.
      */
      A.pExpr = sqlite3PExpr(pParse, TK_INTEGER, 0, 0, &sqlite3IntTokens[N]);
      sqlite3ExprDelete(pParse->db, X.pExpr);















    }else{
      A.pExpr = sqlite3PExpr(pParse, TK_IN, X.pExpr, 0, 0);
      if( A.pExpr ){
        A.pExpr->x.pList = Y;
        sqlite3ExprSetHeight(pParse, A.pExpr);
      }else{
        sqlite3ExprListDelete(pParse->db, Y);







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      **      expr1 NOT IN ()
      **
      ** simplify to constants 0 (false) and 1 (true), respectively,
      ** regardless of the value of expr1.
      */
      A.pExpr = sqlite3PExpr(pParse, TK_INTEGER, 0, 0, &sqlite3IntTokens[N]);
      sqlite3ExprDelete(pParse->db, X.pExpr);
    }else if( Y->nExpr==1 ){
      /* Expressions of the form:
      **
      **      expr1 IN (?1)
      **      expr1 NOT IN (?2)
      **
      ** with exactly one value on the RHS can be simplified to:
      **
      **      expr1 == ?1
      **      expr1 <> ?2
      */
      Expr *pRHS = Y->a[0].pExpr;
      Y->a[0].pExpr = 0;
      sqlite3ExprListDelete(pParse->db, Y);
      A.pExpr = sqlite3PExpr(pParse, N ? TK_NE : TK_EQ, X.pExpr, pRHS, 0);
    }else{
      A.pExpr = sqlite3PExpr(pParse, TK_IN, X.pExpr, 0, 0);
      if( A.pExpr ){
        A.pExpr->x.pList = Y;
        sqlite3ExprSetHeight(pParse, A.pExpr);
      }else{
        sqlite3ExprListDelete(pParse->db, Y);

Changes to src/where.c.

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      if( ExprHasProperty(pExpr, EP_xIsSelect) ){
        /* "x IN (SELECT ...)":  TUNING: the SELECT returns 25 rows */
        nIn = 46;  assert( 46==sqlite3LogEst(25) );
      }else if( ALWAYS(pExpr->x.pList && pExpr->x.pList->nExpr) ){
        /* "x IN (value, value, ...)" */
        nIn = sqlite3LogEst(pExpr->x.pList->nExpr);
      }


      pNew->rRun += nIn;
      pNew->u.btree.nEq++;
      pNew->nOut = nRowEst + nInMul + nIn;
    }else if( pTerm->eOperator & (WO_EQ) ){
      assert(
        (pNew->wsFlags & (WHERE_COLUMN_NULL|WHERE_COLUMN_IN|WHERE_SKIPSCAN))!=0
        || nInMul==0







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      if( ExprHasProperty(pExpr, EP_xIsSelect) ){
        /* "x IN (SELECT ...)":  TUNING: the SELECT returns 25 rows */
        nIn = 46;  assert( 46==sqlite3LogEst(25) );
      }else if( ALWAYS(pExpr->x.pList && pExpr->x.pList->nExpr) ){
        /* "x IN (value, value, ...)" */
        nIn = sqlite3LogEst(pExpr->x.pList->nExpr);
      }
      assert( nIn>0 );  /* RHS always has 2 or more terms...  The parser
                        ** changes "x IN (?)" into "x=?". */
      pNew->rRun += nIn;
      pNew->u.btree.nEq++;
      pNew->nOut = nRowEst + nInMul + nIn;
    }else if( pTerm->eOperator & (WO_EQ) ){
      assert(
        (pNew->wsFlags & (WHERE_COLUMN_NULL|WHERE_COLUMN_IN|WHERE_SKIPSCAN))!=0
        || nInMul==0

Changes to test/in4.test.

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} {}
do_test in4-3.11 {
  execsql { SELECT * FROM t3 WHERE x IN (1, 2) OR y IN ()}
} {1 1 1}
do_test in4-3.12 {
  execsql { SELECT * FROM t3 WHERE x IN (1, 2) AND y IN ()}
} {}

























































































finish_test








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} {}
do_test in4-3.11 {
  execsql { SELECT * FROM t3 WHERE x IN (1, 2) OR y IN ()}
} {1 1 1}
do_test in4-3.12 {
  execsql { SELECT * FROM t3 WHERE x IN (1, 2) AND y IN ()}
} {}

# Tests for "... IN (?)" and "... NOT IN (?)".  In other words, tests
# for when the RHS of IN is a single expression.  This should work the
# same as the == and <> operators.
#
do_execsql_test in4-3.21 {
  SELECT * FROM t3 WHERE x=10 AND y IN (10);
} {10 10 10}
do_execsql_test in4-3.22 {
  SELECT * FROM t3 WHERE x IN (10) AND y=10;
} {10 10 10}
do_execsql_test in4-3.23 {
  SELECT * FROM t3 WHERE x IN (10) AND y IN (10);
} {10 10 10}
do_execsql_test in4-3.24 {
  SELECT * FROM t3 WHERE x=1 AND y NOT IN (10);
} {1 1 1}
do_execsql_test in4-3.25 {
  SELECT * FROM t3 WHERE x  NOT IN (10) AND y=1;
} {1 1 1}
do_execsql_test in4-3.26 {
  SELECT * FROM t3 WHERE x NOT IN (10) AND y NOT IN (10);
} {1 1 1}

# The query planner recognizes that "x IN (?)" only generates a
# single match and can use this information to optimize-out ORDER BY
# clauses.
#
do_execsql_test in4-3.31 {
  DROP INDEX t3i1;
  CREATE UNIQUE INDEX t3xy ON t3(x,y);

  SELECT *, '|' FROM t3 A, t3 B
   WHERE A.x=10 AND A.y IN (10)
     AND B.x=1 AND B.y IN (1);
} {10 10 10 1 1 1 |}
do_execsql_test in4-3.32 {
  EXPLAIN QUERY PLAN
  SELECT *, '|' FROM t3 A, t3 B
   WHERE A.x=10 AND A.y IN (10)
     AND B.x=1 AND B.y IN (1);
} {~/B-TREE/}  ;# No separate sorting pass
do_execsql_test in4-3.33 {
  SELECT *, '|' FROM t3 A, t3 B
   WHERE A.x IN (10) AND A.y=10
     AND B.x IN (1) AND B.y=1;
} {10 10 10 1 1 1 |}
do_execsql_test in4-3.34 {
  EXPLAIN QUERY PLAN
  SELECT *, '|' FROM t3 A, t3 B
   WHERE A.x IN (10) AND A.y=10
     AND B.x IN (1) AND B.y=1;
} {~/B-TREE/}  ;# No separate sorting pass

# An expression of the form "x IN (?,?)" creates an ephemeral table to
# hold the list of values on the RHS.  But "x IN (?)" does not create
# an ephemeral table.
#
do_execsql_test in4-3.41 {
  SELECT * FROM t3 WHERE x IN (10,11);
} {10 10 10}
do_execsql_test in4-3.42 {
  EXPLAIN
  SELECT * FROM t3 WHERE x IN (10,11);
} {/OpenEphemeral/}
do_execsql_test in4-3.43 {
  SELECT * FROM t3 WHERE x IN (10);
} {10 10 10}
do_execsql_test in4-3.44 {
  EXPLAIN
  SELECT * FROM t3 WHERE x IN (10);
} {~/OpenEphemeral/}
do_execsql_test in4-3.45 {
  SELECT * FROM t3 WHERE x NOT IN (10,11);
} {1 1 1}
do_execsql_test in4-3.46 {
  EXPLAIN
  SELECT * FROM t3 WHERE x NOT IN (10,11);
} {/OpenEphemeral/}
do_execsql_test in4-3.47 {
  SELECT * FROM t3 WHERE x NOT IN (10);
} {1 1 1}
do_execsql_test in4-3.48 {
  EXPLAIN
  SELECT * FROM t3 WHERE x NOT IN (10);
} {~/OpenEphemeral/}



finish_test