diff options
| author | Tom Lane <tgl@sss.pgh.pa.us> | 2016-03-27 18:21:03 -0400 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2016-03-27 18:21:03 -0400 |
| commit | d65b665d524a67273b075f468bf3d60ce31f4040 (patch) | |
| tree | deffd09db05b4db461b3b054373cb8d411a0e2d4 /src/backend/utils/adt/selfuncs.c | |
| parent | fa09f8935156533584b4e215bdf70ec1ff968dad (diff) | |
Guard against zero vardata.rel->tuples in estimate_hash_bucketsize().
If the referenced rel was proven empty, we'd compute 0/0 here, which
results in the function returning NaN. That's a bit more serious
than the other zero-divide case. Still, it only seems to be possible
in HEAD, so no back-patch.
Per report from Piotr Stefaniak. I looked through the rest of selfuncs.c
and found no other likely trouble spots.
Diffstat (limited to 'src/backend/utils/adt/selfuncs.c')
| -rw-r--r-- | src/backend/utils/adt/selfuncs.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/src/backend/utils/adt/selfuncs.c b/src/backend/utils/adt/selfuncs.c index 30751fc8ac6..a6555e91b77 100644 --- a/src/backend/utils/adt/selfuncs.c +++ b/src/backend/utils/adt/selfuncs.c @@ -3540,7 +3540,7 @@ estimate_hash_bucketsize(PlannerInfo *root, Node *hashkey, double nbuckets) * XXX Possibly better way, but much more expensive: multiply by * selectivity of rel's restriction clauses that mention the target Var. */ - if (vardata.rel) + if (vardata.rel && vardata.rel->tuples > 0) { ndistinct *= vardata.rel->rows / vardata.rel->tuples; ndistinct = clamp_row_est(ndistinct); |