Documentation
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Index ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func GetTopNRows ¶
func GetTopNRows(ctx *sql.Context, iter sql.RowIter, sortConditions sql.SortConditions, n int64) ([]sql.Row, int64, error)
GetTopNRows uses a Top-N Heap Sort to find the top (min) N rows in a RowIter. It inserts each row of the iter into the max-heap, popping the max row if the size of the heap exceeds N such that the heap only contains the N min rows. At the end, it pops the contents of the heap and returns them in min-first order.
Types ¶
type RowSorter ¶
type RowSorter struct {
// contains filtered or unexported fields
}
RowSorter is a sorter implementation for Row slices using SortFields for the comparison. RowSorter can act as simply a container for sort conditions, or as a sorter for a slice of rows. If the latter, it caches the evaluated sort keys for each row to avoid re-evaluating them during sorting, which is necessary for correctness and desirable for performance.
func NewRowSorter ¶
func NewRowSorter(ctx *sql.Context, sortConditions sql.SortConditions) *RowSorter
NewRowSorter creates a RowSorter for the given sort conditions
func NewRowSorterWithRows ¶
func NewRowSorterWithRows(ctx *sql.Context, sortConditions sql.SortConditions, rows []sql.Row) *RowSorter
NewRowSorterWithRows creates a RowSorter for the given sort conditions and rows.
func (*RowSorter) CompareKeys ¶
CompareKeys compares two sort keys produced by EvalKey based on s.sortConditions. Either key may be nil (a failed evaluation), in which case the comparison result is 0.
func (*RowSorter) EvalKey ¶
EvalKey evaluates the sort condition expressions for the given row, returning the resulting sort key. If any expression fails to evaluate, EvalKey records the error (see GetError) and returns nil.
Source Files