diff options
Diffstat (limited to 'src/backend/utils/adt/selfuncs.c')
| -rw-r--r-- | src/backend/utils/adt/selfuncs.c | 18 |
1 files changed, 16 insertions, 2 deletions
diff --git a/src/backend/utils/adt/selfuncs.c b/src/backend/utils/adt/selfuncs.c index 56943f2a87a..4973396b80d 100644 --- a/src/backend/utils/adt/selfuncs.c +++ b/src/backend/utils/adt/selfuncs.c @@ -2511,10 +2511,24 @@ eqjoinsel_semi(Oid operator, * We can apply this clamping both with respect to the base relation from * which the join variable comes (if there is just one), and to the * immediate inner input relation of the current join. + * + * If we clamp, we can treat nd2 as being a non-default estimate; it's not + * great, maybe, but it didn't come out of nowhere either. This is most + * helpful when the inner relation is empty and consequently has no stats. */ if (vardata2->rel) - nd2 = Min(nd2, vardata2->rel->rows); - nd2 = Min(nd2, inner_rel->rows); + { + if (nd2 >= vardata2->rel->rows) + { + nd2 = vardata2->rel->rows; + isdefault2 = false; + } + } + if (nd2 >= inner_rel->rows) + { + nd2 = inner_rel->rows; + isdefault2 = false; + } if (HeapTupleIsValid(vardata1->statsTuple)) { |