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Overview
Comment:Whenever a generated column is used, assume that all columns are used.
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SHA3-256: 6601da58032d18ae00b466c0f2077fb2b1ecd84225b56e1787724bea478eedc9
User & Date: drh 2019-11-21 19:37:00
References
2019-12-08
00:06
Fix incorrect column-usage accounting associated with generated columns and added by check-in [6601da58032d18ae]. Fix for ticket [b92e5e8ec2cdbaa1]. check-in: 9d75e1cc user: drh tags: trunk
Context
2019-11-21
20:10
Fix an out-of-bounds array reference in the generated column logic. Problem discovered by valgrind. check-in: a0ab42f7 user: drh tags: trunk
19:37
Whenever a generated column is used, assume that all columns are used. check-in: 6601da58 user: drh tags: trunk
18:28
Fix a problem that comes up when using generated columns that evaluate to a constant in an index and then making use of that index in a join. check-in: 8b12e95f user: drh tags: trunk
Changes
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Changes to src/resolve.c.

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    }
    pParse->checkSchema = 1;
    pTopNC->nErr++;
  }

  /* If a column from a table in pSrcList is referenced, then record
  ** this fact in the pSrcList.a[].colUsed bitmask.  Column 0 causes
  ** bit 0 to be set.  Column 1 sets bit 1.  And so forth.  If the







  ** column number is greater than the number of bits in the bitmask
  ** then set the high-order bit of the bitmask.


  */
  if( pExpr->iColumn>=0 && pMatch!=0 ){
    int n = pExpr->iColumn;
    testcase( n==BMS-1 );
    if( n>=BMS ){
      n = BMS-1;
    }

    assert( pMatch->iCursor==pExpr->iTable );




    pMatch->colUsed |= ((Bitmask)1)<<n;
  }

  /* Clean up and return
  */
  sqlite3ExprDelete(db, pExpr->pLeft);
  pExpr->pLeft = 0;







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    }
    pParse->checkSchema = 1;
    pTopNC->nErr++;
  }

  /* If a column from a table in pSrcList is referenced, then record
  ** this fact in the pSrcList.a[].colUsed bitmask.  Column 0 causes
  ** bit 0 to be set.  Column 1 sets bit 1.  And so forth.
  **
  ** The colUsed mask is an optimization used to help determine if an
  ** index is a covering index.  The correct answer is still obtained
  ** if the mask contains extra bits.  But omitting bits from the mask
  ** might result in an incorrect answer.
  **
  ** The high-order bit of the mask is a "we-use-them-all" bit.
  ** If the column number is greater than the number of bits in the bitmask
  ** then set the high-order bit of the bitmask.  Also set the high-order
  ** bit if the column is a generated column, as that adds dependencies
  ** that are difficult to track, so we assume that all columns are used.
  */
  if( pExpr->iColumn>=0 && pMatch!=0 ){
    int n = pExpr->iColumn;
    testcase( n==BMS-1 );
    if( n>=BMS ){
      n = BMS-1;
    }
    assert( pExpr->y.pTab!=0 );
    assert( pMatch->iCursor==pExpr->iTable );
    if( pExpr->y.pTab->tabFlags & TF_HasGenerated ){
      Column *pCol = pExpr->y.pTab->aCol + pExpr->iColumn;
      if( pCol->colFlags & COLFLAG_GENERATED ) n = BMS-1;
    }
    pMatch->colUsed |= ((Bitmask)1)<<n;
  }

  /* Clean up and return
  */
  sqlite3ExprDelete(db, pExpr->pLeft);
  pExpr->pLeft = 0;

Changes to test/gencol1.test.

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  );
  UPDATE t0 SET c0 = NULL;
} {1 {generated column loop on "c2"}}

# 2019-11-21 Problems in the new generated column logic
# reported by Yongheng Chen and Rui Zhong
do_execsql_test gencol1-9.10 {
  DROP TABLE IF EXISTS t1;
  DROP TABLE IF EXISTS t2;
  CREATE TABLE t1(aa , bb AS (17) UNIQUE);
  INSERT INTO t1 VALUES(17);
  CREATE TABLE t2(cc);
  INSERT INTO t2 VALUES(41);
  SELECT * FROM t2 JOIN t1 WHERE t1.bb=t1.aa AND t1.bb=17;
} {41 17 17}









finish_test







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  );
  UPDATE t0 SET c0 = NULL;
} {1 {generated column loop on "c2"}}

# 2019-11-21 Problems in the new generated column logic
# reported by Yongheng Chen and Rui Zhong
do_execsql_test gencol1-9.10 {
  DROP TABLE t1;

  CREATE TABLE t1(aa , bb AS (17) UNIQUE);
  INSERT INTO t1 VALUES(17);
  CREATE TABLE t2(cc);
  INSERT INTO t2 VALUES(41);
  SELECT * FROM t2 JOIN t1 WHERE t1.bb=t1.aa AND t1.bb=17;
} {41 17 17}
do_execsql_test gencol1-9.20 {
  CREATE TABLE t3(aa INT PRIMARY KEY, bb UNIQUE AS(aa));
  INSERT INTO t3 VALUES(1);
  SELECT 100, * FROM t3;
  DELETE FROM t3 WHERE (SELECT bb FROM t3);
  SELECT 200, * FROM t3;
} {100 1 1}


finish_test