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| author | drh <drh@noemail.net> | 2011-03-17 01:58:21 +0000 |
|---|---|---|
| committer | drh <drh@noemail.net> | 2011-03-17 01:58:21 +0000 |
| commit | ac8eb11375458631836e42f43164e88c3f569df5 (patch) | |
| tree | c7b5b99eae43651fbebf1eb7e46e9dc66715bcfa /src | |
| parent | 1f9c7663ce09be70beb0259fa2c71c165cab4325 (diff) | |
| download | sqlite-ac8eb11375458631836e42f43164e88c3f569df5.tar.gz sqlite-ac8eb11375458631836e42f43164e88c3f569df5.zip | |
Comment enhancement to better explain the logic in the "x IS NULL"
optimization.
FossilOrigin-Name: 869f894798a65f8bc0e0b083866a784fa0189f68
Diffstat (limited to 'src')
| -rw-r--r-- | src/where.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/src/where.c b/src/where.c index 0cda03f45..cdcaa98c0 100644 --- a/src/where.c +++ b/src/where.c @@ -2520,7 +2520,8 @@ range_est_fallback: ** an equality constraint x=VALUE and where that VALUE occurs in ** the histogram data. This only works when x is the left-most ** column of an index and sqlite_stat2 histogram data is available -** for that index. +** for that index. When pExpr==NULL that means the constraint is +** "x IS NULL" instead of "x=VALUE". ** ** Write the estimated row count into *pnRow and return SQLITE_OK. ** If unable to make an estimate, leave *pnRow unchanged and return |