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Diffstat (limited to 'src/include/nodes/parsenodes.h')
| -rw-r--r-- | src/include/nodes/parsenodes.h | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h index 904bd5e9e18..b7e7104f44d 100644 --- a/src/include/nodes/parsenodes.h +++ b/src/include/nodes/parsenodes.h @@ -787,7 +787,12 @@ typedef struct RangeTblEntry * * In an ORDER BY item, all fields must be valid. (The eqop isn't essential * here, but it's cheap to get it along with the sortop, and requiring it - * to be valid eases comparisons to grouping items.) + * to be valid eases comparisons to grouping items.) Note that this isn't + * actually enough information to determine an ordering: if the sortop is + * collation-sensitive, a collation OID is needed too. We don't store the + * collation in SortGroupClause because it's not available at the time the + * parser builds the SortGroupClause; instead, consult the exposed collation + * of the referenced targetlist expression to find out what it is. * * In a grouping item, eqop must be valid. If the eqop is a btree equality * operator, then sortop should be set to a compatible ordering operator. |