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Fix incorrect column-usage accounting associated with generated columns

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and added by check-in [6601da58032d18ae].  Fix for ticket [b92e5e8ec2cdbaa1].

FossilOrigin-Name: 9d75e1ccc72e9f536f45df3b24e9ecd25076cc1f7cf16b806b19e0e1b68e8326
This commit is contained in:
drh
2019-12-08 00:06:39 +00:00
parent 29cdbadf8a
commit bf9d0996b9
3 changed files with 28 additions and 19 deletions
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33
src/resolve.c
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@@ -551,30 +551,39 @@ static int lookupName(
/* 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.
** bit 0 to be set. Column 1 sets bit 1. And so forth. Bit 63 is
** set if the 63rd or any subsequent column is used.
**
** 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.
** if the mask contains extra set bits. However, it is important to
** avoid setting bits beyond the maximum column number of the table.
** (See ticket [b92e5e8ec2cdbaa1]).
**
** 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 a generated column is referenced, set bits for every column
** of the table.
*/
if( pExpr->iColumn>=0 && pMatch!=0 ){
int n = pExpr->iColumn;
Table *pTab;
testcase( n==BMS-1 );
if( n>=BMS ){
n = BMS-1;
}
assert( pExpr->y.pTab!=0 );
pTab = pExpr->y.pTab;
assert( pTab!=0 );
assert( pMatch->iCursor==pExpr->iTable );
if( pExpr->y.pTab->tabFlags & TF_HasGenerated ){
Column *pColumn = pExpr->y.pTab->aCol + pExpr->iColumn;
if( pColumn->colFlags & COLFLAG_GENERATED ) n = BMS-1;
if( pTab->tabFlags & TF_HasGenerated ){
Column *pColumn = pTab->aCol + pExpr->iColumn;
if( pColumn->colFlags & COLFLAG_GENERATED ){
testcase( pTab->nCol==63 );
testcase( pTab->nCol==64 );
if( pTab->nCol>=64 ){
pMatch->colUsed = ALLBITS;
}else{
pMatch->colUsed = MASKBIT(pTab->nCol)-1;
}
}
}
pMatch->colUsed |= ((Bitmask)1)<<n;
}