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Golang Datum.HasPrev方法代碼示例

本文整理匯總了Golang中github.com/cockroachdb/cockroach/pkg/sql/parser.Datum.HasPrev方法的典型用法代碼示例。如果您正苦於以下問題:Golang Datum.HasPrev方法的具體用法?Golang Datum.HasPrev怎麽用?Golang Datum.HasPrev使用的例子?那麽, 這裏精選的方法代碼示例或許可以為您提供幫助。您也可以進一步了解該方法所在github.com/cockroachdb/cockroach/pkg/sql/parser.Datum的用法示例。


在下文中一共展示了Datum.HasPrev方法的1個代碼示例,這些例子默認根據受歡迎程度排序。您可以為喜歡或者感覺有用的代碼點讚,您的評價將有助於係統推薦出更棒的Golang代碼示例。

示例1: encodeInclusiveEndValue

// Encodes datum at the end of key, using direction `dir` for the encoding.
// It takes in an inclusive key and returns an inclusive key if
// isLastEndConstraint is not set, and an exclusive key otherwise (the idea is
// that, for inclusive constraints, the value for the last column in the
// constraint needs to be adapted to an exclusive span.EndKey).
func encodeInclusiveEndValue(
	key roachpb.Key, datum parser.Datum, dir encoding.Direction, isLastEndConstraint bool,
) roachpb.Key {
	// Since the end of a span is exclusive, if the last constraint is an
	// inclusive one, we might need to make the key exclusive by applying a
	// PrefixEnd().  We normally avoid doing this by transforming "a = x" to
	// "a = x±1" for the last end constraint, depending on the encoding direction
	// (since this keeps the key nice and pretty-printable).
	// However, we might not be able to do the ±1.
	needExclusiveKey := false
	if isLastEndConstraint {
		if dir == encoding.Ascending {
			if datum.IsMax() || !datum.HasNext() {
				needExclusiveKey = true
			} else {
				datum = datum.Next()
			}
		} else {
			if datum.IsMin() || !datum.HasPrev() {
				needExclusiveKey = true
			} else {
				datum = datum.Prev()
			}
		}
	}
	key, err := sqlbase.EncodeTableKey(key, datum, dir)
	if err != nil {
		panic(err)
	}
	if needExclusiveKey {
		key = key.PrefixEnd()
	}
	return key
}
開發者ID:veteranlu,項目名稱:cockroach,代碼行數:39,代碼來源:index_selection.go


注:本文中的github.com/cockroachdb/cockroach/pkg/sql/parser.Datum.HasPrev方法示例由純淨天空整理自Github/MSDocs等開源代碼及文檔管理平台,相關代碼片段篩選自各路編程大神貢獻的開源項目,源碼版權歸原作者所有,傳播和使用請參考對應項目的License;未經允許,請勿轉載。