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| -rw-r--r-- | src/backend/statistics/README.dependencies | 4 | ||||
| -rw-r--r-- | src/backend/statistics/dependencies.c | 8 |
2 files changed, 0 insertions, 12 deletions
diff --git a/src/backend/statistics/README.dependencies b/src/backend/statistics/README.dependencies index 702d34e3f80..6c446bde274 100644 --- a/src/backend/statistics/README.dependencies +++ b/src/backend/statistics/README.dependencies @@ -71,10 +71,6 @@ To count the rows consistent with the dependency (a => b): (c) If there's a single distinct value in 'b', the rows are consistent with the functional dependency, otherwise they contradict it. -The algorithm also requires a minimum size of the group to consider it -consistent (currently 3 rows in the sample). Small groups make it less likely -to break the consistency. - Clause reduction (planner/optimizer) ------------------------------------ diff --git a/src/backend/statistics/dependencies.c b/src/backend/statistics/dependencies.c index 89dece33504..2e7c0ad6ba6 100644 --- a/src/backend/statistics/dependencies.c +++ b/src/backend/statistics/dependencies.c @@ -286,14 +286,6 @@ dependency_degree(int numrows, HeapTuple *rows, int k, AttrNumber *dependency, * first (k-1) columns. If there's a single value in the last column, we * count the group as 'supporting' the functional dependency. Otherwise we * count it as contradicting. - * - * We also require a group to have a minimum number of rows to be - * considered useful for supporting the dependency. Contradicting groups - * may be of any size, though. - * - * XXX The minimum size requirement makes it impossible to identify case - * when both columns are unique (or nearly unique), and therefore - * trivially functionally dependent. */ /* start with the first row forming a group */ |