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If a query like "SELECT min(a), b FROM t1" visits no rows where "a" is not null, extract a value for "b" from one of the rows where "a" is null. Possible fix for ticket [41866dc37].

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FossilOrigin-Name: a7277ed0623dccdbf775ae6127611d6bc6e150f6942a048ab4281e5136c0e98d
This commit is contained in:
dan
2019-08-02 18:43:59 +00:00
parent d744ee0b50
commit ddd7421c91
4 changed files with 60 additions and 10 deletions
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19
src/wherecode.c
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@@ -1694,6 +1694,25 @@ Bitmask sqlite3WhereCodeOneLoopStart(
VdbeCoverageIf(v, op==OP_SeekGE); testcase( op==OP_SeekGE );
VdbeCoverageIf(v, op==OP_SeekLE); testcase( op==OP_SeekLE );
VdbeCoverageIf(v, op==OP_SeekLT); testcase( op==OP_SeekLT );
if( bSeekPastNull && (pLoop->wsFlags & WHERE_TOP_LIMIT)==0 ){
/* If bSeekPastNull is set only to skip past the NULL values for
** a query like "SELECT min(a), b FROM t1", then add code so that
** if there are no rows with (a IS NOT NULL), then do the seek
** without jumping past NULLs instead. This allows the code in
** select.c to pick a value for "b" in the above query. */
assert( startEq==0 && (op==OP_SeekGT || op==OP_SeekLT) );
assert( (pWInfo->wctrlFlags&WHERE_ORDERBY_MIN)!=0 && pWInfo->nOBSat>0 );
sqlite3VdbeChangeP2(v, -1, sqlite3VdbeCurrentAddr(v)+1);
sqlite3VdbeAddOp2(v, OP_Goto, 0, sqlite3VdbeCurrentAddr(v)+2);
op = aStartOp[(start_constraints<<2) + (1<<1) + bRev];
assert( op!=0 );
sqlite3VdbeAddOp4Int(v, op, iIdxCur, addrNxt, regBase, nConstraint);
VdbeCoverage(v);
VdbeCoverageIf(v, op==OP_SeekGE); testcase( op==OP_SeekGE );
VdbeCoverageIf(v, op==OP_SeekLE); testcase( op==OP_SeekLE );
}
}
/* Load the value for the inequality constraint at the end of the