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data-structure.md

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Data Structure

The syntax here is modeled after Redis commands

List

RPush Inserts the values at the tail of the list stored in the bucket at given bucket, key and values. 
if err := db.Update(
    func(tx *nutsdb.Tx) error {
        bucket := "bucketForList"
        key := []byte("myList")
        val := []byte("val1")
        return tx.RPush(bucket, key, val)
    }); err != nil {
    log.Fatal(err)
}
LPush Inserts the values at the head of the list stored in the bucket at given bucket, key and values. 
if err := db.Update(
    func(tx *nutsdb.Tx) error {
        bucket := "bucketForList"
        key := []byte("myList")
        val := []byte("val2")
        return tx.LPush(bucket, key, val)
    }); err != nil {
    log.Fatal(err)
}
LPop Removes and returns the first element of the list stored in the bucket at given bucket and key. 
if err := db.Update(
    func(tx *nutsdb.Tx) error {
        bucket := "bucketForList"
        key := []byte("myList")
        if item, err := tx.LPop(bucket, key); err != nil {
            return err
        } else {
            fmt.Println("LPop item:", string(item))
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}
LPeek Returns the first element of the list stored in the bucket at given bucket and key. 
if err := db.View(
    func(tx *nutsdb.Tx) error {
        bucket := "bucketForList"
        key := []byte("myList")
        if item, err := tx.LPeek(bucket, key); err != nil {
            return err
        } else {
            fmt.Println("LPeek item:", string(item)) //val11
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}
RPop Removes and returns the last element of the list stored in the bucket at given bucket and key. 
if err := db.Update(
    func(tx *nutsdb.Tx) error {
        bucket := "bucketForList"
        key := []byte("myList")
        if item, err := tx.RPop(bucket, key); err != nil {
            return err
        } else {
            fmt.Println("RPop item:", string(item))
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}
RPeek Returns the last element of the list stored in the bucket at given bucket and key. 
if err := db.View(
    func(tx *nutsdb.Tx) error {
        bucket := "bucketForList"
        key := []byte("myList")
        if item, err := tx.RPeek(bucket, key); err != nil {
            return err
        } else {
            fmt.Println("RPeek item:", string(item))
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}
LRange Returns the specified elements of the list stored in the bucket at given bucket,key, start and end. The offsets start and stop are zero-based indexes 0 being the first element of the list (the head of the list), 1 being the next element and so on. Start and end can also be negative numbers indicating offsets from the end of the list, where -1 is the last element of the list, -2 the penultimate element and so on. 
if err := db.View(
    func(tx *nutsdb.Tx) error {
        bucket := "bucketForList"
        key := []byte("myList")
        if items, err := tx.LRange(bucket, key, 0, -1); err != nil {
            return err
        } else {
            //fmt.Println(items)
            for _, item := range items {
                fmt.Println(string(item))
            }
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}
LRem Note: This feature can be used starting from v0.6.0

Removes the first count occurrences of elements equal to value from the list stored in the bucket at given bucket,key,count. The count argument influences the operation in the following ways:

  • count > 0: Remove elements equal to value moving from head to tail.
  • count < 0: Remove elements equal to value moving from tail to head.
  • count = 0: Remove all elements equal to value.
if err := db.Update(
    func(tx *nutsdb.Tx) error {
        bucket := "bucketForList"
        key := []byte("myList")
        return tx.LRem(bucket, key, 1, []byte("value11))
    }); err != nil {
    log.Fatal(err)
}
LRemByIndex Note: This feature can be used starting from v0.10.0

Remove the element at a specified position (single or multiple) from the list

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        bucket := "bucketForList"
        key := []byte("myList")
        removedNum, err := tx.LRemByIndex(bucket, key, 0, 1)
        fmt.Printf("removed num %d\n", removedNum)
        return err
    }); err != nil {
    log.Fatal(err)
}
LTrim Trims an existing list so that it will contain only the specified range of elements specified. The offsets start and stop are zero-based indexes 0 being the first element of the list (the head of the list), 1 being the next element and so on.Start and end can also be negative numbers indicating offsets from the end of the list, where -1 is the last element of the list, -2 the penultimate element and so on. 
if err := db.Update(
    func(tx *nutsdb.Tx) error {
        bucket := "bucketForList"
        key := []byte("myList")
        return tx.LTrim(bucket, key, 0, 1)
    }); err != nil {
    log.Fatal(err)
}
LSize Returns the size of key in the bucket in the bucket at given bucket and key. 
if err := db.Update(
    func(tx *nutsdb.Tx) error {
        bucket := "bucketForList"
        key := []byte("myList")
        if size,err := tx.LSize(bucket, key); err != nil {
            return err
        } else {
            fmt.Println("myList size is ",size)
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}
LKeys find all keys of type List matching a given pattern, similar to Redis command: KEYS

Note: pattern matching use filepath.Match, It is different from redis' behavior in some details, such as [.

if err := db.View(
    func(tx *nutsdb.Tx) error {
        var keys []string
        err := tx.LKeys(bucket, "*", func(key string) bool {
            keys = append(keys, key)
            // true: continue, false: break
            return true
        })
        fmt.Printf("keys: %v\n", keys)
        return err
    }); err != nil {
    log.Fatal(err)
}

Set

SAdd Adds the specified members to the set stored int the bucket at given bucket,key and items. 
if err := db.Update(
    func(tx *nutsdb.Tx) error {
        bucket := "bucketForSet"
        key := []byte("mySet")
        return tx.SAdd(bucket, key, []byte("a"), []byte("b"), []byte("c"))
    }); err != nil {
    log.Fatal(err)
}
SAreMembers Returns if the specified members are the member of the set int the bucket at given bucket,key and items. 
if err := db.View(
    func(tx *nutsdb.Tx) error {
        bucket := "bucketForSet"
        key := []byte("mySet")
        if ok, err := tx.SAreMembers(bucket, key, []byte("a"), []byte("b"), []byte("c")); err != nil {
            return err
        } else {
            fmt.Println("SAreMembers:", ok)
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}
SCard Returns the set cardinality (number of elements) of the set stored in the bucket at given bucket and key. 
if err := db.View(
    func(tx *nutsdb.Tx) error {
        bucket := "bucketForSet"
        key := []byte("mySet")
        if num, err := tx.SCard(bucket, key); err != nil {
            return err
        } else {
            fmt.Println("SCard:", num)
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}
SDiffByOneBucket Returns the members of the set resulting from the difference between the first set and all the successive sets in one bucket. 
key1 := []byte("mySet1")
key2 := []byte("mySet2")
bucket := "bucketForSet"

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        return tx.SAdd(bucket, key1, []byte("a"), []byte("b"), []byte("c"))
    }); err != nil {
    log.Fatal(err)
}

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        return tx.SAdd(bucket, key2, []byte("c"), []byte("d"))
    }); err != nil {
    log.Fatal(err)
}

if err := db.View(
    func(tx *nutsdb.Tx) error {
        if items, err := tx.SDiffByOneBucket(bucket, key1, key2); err != nil {
            return err
        } else {
            fmt.Println("SDiffByOneBucket:", items)
            for _, item := range items {
                fmt.Println("item", string(item))
            }
            //item a
            //item b
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}
SDiffByTwoBuckets Returns the members of the set resulting from the difference between the first set and all the successive sets in two buckets. 
bucket1 := "bucket1"
key1 := []byte("mySet1")

bucket2 := "bucket2"
key2 := []byte("mySet2")

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        return tx.SAdd(bucket1, key1, []byte("a"), []byte("b"), []byte("c"))
    }); err != nil {
    log.Fatal(err)
}

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        return tx.SAdd(bucket2, key2, []byte("c"), []byte("d"))
    }); err != nil {
    log.Fatal(err)
}

if err := db.View(
    func(tx *nutsdb.Tx) error {
        if items, err := tx.SDiffByTwoBuckets(bucket1, key1, bucket2, key2); err != nil {
            return err
        } else {
            fmt.Println("SDiffByTwoBuckets:", items)
            for _, item := range items {
                fmt.Println("item", string(item))
            }
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}
SHasKey Returns if the set in the bucket at given bucket and key. 
bucket := "bucketForSet"

if err := db.View(
    func(tx *nutsdb.Tx) error {
        if ok, err := tx.SHasKey(bucket, []byte("mySet")); err != nil {
            return err
        } else {
            fmt.Println("SHasKey", ok)
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}
SIsMember Returns if member is a member of the set stored in the bucket at given bucket, key and item. 
bucket := "bucketForSet"

if err := db.View(
    func(tx *nutsdb.Tx) error {
        if ok, err := tx.SIsMember(bucket, []byte("mySet"), []byte("a")); err != nil {
            return err
        } else {
            fmt.Println("SIsMember", ok)
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}
SMembers Returns all the members of the set value stored in the bucket at given bucket and key. 
bucket := "bucketForSet"

if err := db.View(
    func(tx *nutsdb.Tx) error {
        if items, err := tx.SMembers(bucket, []byte("mySet")); err != nil {
            return err
        } else {
            fmt.Println("SMembers", items)
            for _, item := range items {
                fmt.Println("item", string(item))
            }
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}
SMoveByOneBucket Moves member from the set at source to the set at destination in one bucket. 
bucket3 := "bucket3"

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        return tx.SAdd(bucket3, []byte("mySet1"), []byte("a"), []byte("b"), []byte("c"))
    }); err != nil {
    log.Fatal(err)
}
if err := db.Update(
    func(tx *nutsdb.Tx) error {
        return tx.SAdd(bucket3, []byte("mySet2"), []byte("c"), []byte("d"), []byte("e"))
    }); err != nil {
    log.Fatal(err)
}

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        if ok, err := tx.SMoveByOneBucket(bucket3, []byte("mySet1"), []byte("mySet2"), []byte("a")); err != nil {
            return err
        } else {
            fmt.Println("SMoveByOneBucket", ok)
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

if err := db.View(
    func(tx *nutsdb.Tx) error {
        if items, err := tx.SMembers(bucket3, []byte("mySet1")); err != nil {
            return err
        } else {
            fmt.Println("after SMoveByOneBucket bucket3 mySet1 SMembers", items)
            for _, item := range items {
                fmt.Println("item", string(item))
            }
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

if err := db.View(
    func(tx *nutsdb.Tx) error {
        if items, err := tx.SMembers(bucket3, []byte("mySet2")); err != nil {
            return err
        } else {
            fmt.Println("after SMoveByOneBucket bucket3 mySet2 SMembers", items)
            for _, item := range items {
                fmt.Println("item", string(item))
            }
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}
SMoveByTwoBuckets Moves member from the set at source to the set at destination in two buckets. 
bucket4 := "bucket4"
bucket5 := "bucket5"
if err := db.Update(
    func(tx *nutsdb.Tx) error {
        return tx.SAdd(bucket4, []byte("mySet1"), []byte("a"), []byte("b"), []byte("c"))
    }); err != nil {
    log.Fatal(err)
}
if err := db.Update(
    func(tx *nutsdb.Tx) error {
        return tx.SAdd(bucket5, []byte("mySet2"), []byte("c"), []byte("d"), []byte("e"))
    }); err != nil {
    log.Fatal(err)
}

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        if ok, err := tx.SMoveByTwoBuckets(bucket4, []byte("mySet1"), bucket5, []byte("mySet2"), []byte("a")); err != nil {
            return err
        } else {
            fmt.Println("SMoveByTwoBuckets", ok)
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

if err := db.View(
    func(tx *nutsdb.Tx) error {
        if items, err := tx.SMembers(bucket4, []byte("mySet1")); err != nil {
            return err
        } else {
            fmt.Println("after SMoveByTwoBuckets bucket4 mySet1 SMembers", items)
            for _, item := range items {
                fmt.Println("item", string(item))
            }
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

if err := db.View(
    func(tx *nutsdb.Tx) error {
        if items, err := tx.SMembers(bucket5, []byte("mySet2")); err != nil {
            return err
        } else {
            fmt.Println("after SMoveByTwoBuckets bucket5 mySet2 SMembers", items)
            for _, item := range items {
                fmt.Println("item", string(item))
            }
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}
SPop Removes and returns one or more random elements from the set value store in the bucket at given bucket and key. 
if err := db.Update(
    func(tx *nutsdb.Tx) error {
        key := []byte("mySet")
        if item, err := tx.SPop(bucket, key); err != nil {
            return err
        } else {
            fmt.Println("SPop item from mySet:", string(item))
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}
SRem Removes the specified members from the set stored in the bucket at given bucket,key and items. 
bucket6:="bucket6"
if err := db.Update(
    func(tx *nutsdb.Tx) error {
        return tx.SAdd(bucket6, []byte("mySet"), []byte("a"), []byte("b"), []byte("c"))
    }); err != nil {
    log.Fatal(err)
}

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        if err := tx.SRem(bucket6, []byte("mySet"), []byte("a")); err != nil {
            return err
        } else {
            fmt.Println("SRem ok")
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}

if err := db.View(
    func(tx *nutsdb.Tx) error {
        if items, err := tx.SMembers(bucket6, []byte("mySet")); err != nil {
            return err
        } else {
            fmt.Println("SMembers items:", items)
            for _, item := range items {
                fmt.Println("item:", string(item))
            }
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}
SUnionByOneBucket The members of the set resulting from the union of all the given sets in one bucket. 
bucket7 := "bucket1"
key1 := []byte("mySet1")
key2 := []byte("mySet2")

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        return tx.SAdd(bucket7, key1, []byte("a"), []byte("b"), []byte("c"))
    }); err != nil {
    log.Fatal(err)
}

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        return tx.SAdd(bucket7, key2, []byte("c"), []byte("d"))
    }); err != nil {
    log.Fatal(err)
}

if err := db.View(
    func(tx *nutsdb.Tx) error {
        if items, err := tx.SUnionByOneBucket(bucket7, key1, key2); err != nil {
            return err
        } else {
            fmt.Println("SUnionByOneBucket:", items)
            for _, item := range items {
                fmt.Println("item", string(item))
            }
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}
SUnionByTwoBuckets The members of the set resulting from the union of all the given sets in two buckets. 
bucket8 := "bucket1"
key1 := []byte("mySet1")

bucket9 := "bucket2"
key2 := []byte("mySet2")

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        return tx.SAdd(bucket8, key1, []byte("a"), []byte("b"), []byte("c"))
    }); err != nil {
    log.Fatal(err)
}

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        return tx.SAdd(bucket9, key2, []byte("c"), []byte("d"))
    }); err != nil {
    log.Fatal(err)
}

if err := db.View(
    func(tx *nutsdb.Tx) error {
        if items, err := tx.SUnionByTwoBuckets(bucket8, key1, bucket9, key2); err != nil {
            return err
        } else {
            fmt.Println("SUnionByTwoBucket:", items)
            for _, item := range items {
                fmt.Println("item", string(item))
            }
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}
SKeys find all keys of type Set matching a given pattern, similar to Redis command: KEYS

Note: pattern matching use filepath.Match, It is different from redis' behavior in some details, such as [.

if err := db.View(
    func(tx *nutsdb.Tx) error {
        var keys []string
        err := tx.SKeys(bucket, "*", func(key string) bool {
            keys = append(keys, key)
            // true: continue, false: break
            return true
        })
        fmt.Printf("keys: %v\n", keys)
        return err
    }); err != nil {
    log.Fatal(err)
}

Sorted Set

ZAdd Adds the specified member with the specified score into the sorted set specified by key in a bucket. 
if err := db.Update(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet1"
        key := []byte("key1")
        return tx.ZAdd(bucket, key, 1, []byte("val1"))
    }); err != nil {
    log.Fatal(err)
}
ZCard Returns the sorted set cardinality (number of elements) of the sorted set specified by key in a bucket. 
if err := db.View(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet1"
        key := []byte("key1")
        num, err := tx.ZCard(bucket, key)
        if err != nil {
            return err
        }
        fmt.Println("ZCard num", num)
        return nil
    }); err != nil {
    log.Fatal(err)
}
ZCount Returns the number of elements in the sorted set specified by key in a bucket with a score between min and max and opts.

Opts include the following parameters:

  • Limit int // limit the max nodes to return
  • ExcludeStart bool // exclude start value, so it search in interval (start, end] or (start, end)
  • ExcludeEnd bool // exclude end value, so it search in interval [start, end) or (start, end)
if err := db.View(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet1"
        key := []byte("key1")
        num, err := tx.ZCount(bucket, key, 0, 1, nil)
        if err != nil {
            return err
        }
        fmt.Println("ZCount num", num)
        return nil
    }); err != nil {
    log.Fatal(err)
}
ZScore Returns the score of members in a sorted set specified by key in a bucket. 
if err := db.View(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet1"
        key := []byte("key1")
        score, err := tx.ZScore(bucket, key, []byte("val1"))
        if err != nil {
            return err
        }
        fmt.Println("val1 score: ", score)
        return nil
    }); err != nil {
    log.Fatal(err)
}
ZMembers Returns all the members and scores of members of the set specified by key in a bucket. 
if err := db.View(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet1"
        key := []byte("key1")
        nodes, err := tx.ZMembers(bucket, key)
        if err != nil {
            return err
        }
        for node := range nodes {
            fmt.Println("member:", node.Score, string(node.Value))
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}
ZPeekMax Returns the member with the highest score in the sorted set specified by key in a bucket. 
if err := db.View(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet1"
        key := []byte("key1")
        node, err := tx.ZPeekMax(bucket, key))
        if err != nil {
            return err
        }
        fmt.Println("ZPeekMax:", node.Score)
        return nil
    }); err != nil {
    log.Fatal(err)
}
ZPeekMin Returns the member with the lowest score in the sorted set specified by key in a bucket. 
if err := db.View(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet1"
        key := []byte("key1")
        node, err := tx.ZPeekMin(bucket, key)
        if err != nil {
            return err
        }
        fmt.Println("ZPeekMin:", node.Score)
        return nil
    }); err != nil {
    log.Fatal(err)
}
ZPopMax Removes and returns the member with the highest score in the sorted set specified by key in a bucket. 
if err := db.Update(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet1"
        key := []byte("key1")
        node, err := tx.ZPopMax(bucket, key)
        if err != nil {
            return err
        }
        fmt.Println("ZPopMax:", node.Score)
        return nil
    }); err != nil {
    log.Fatal(err)
}
ZPopMin Removes and returns the member with the lowest score in the sorted set specified by key in a bucket. 
if err := db.Update(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet1"
        key := []byte("key1")
        node, err := tx.ZPopMin(bucket, key)
        if err != nil {
            return err
        }
        fmt.Println("ZPopMin:", node.Score)
        return nil
    }); err != nil {
    log.Fatal(err)
}
ZRangeByRank Returns all the elements in the sorted set specified by key in a bucket with a rank between start and end (including elements with rank equal to start or end). 
if err := db.Update(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet1"
        key := []byte("key1")
        return tx.ZAdd(bucket, key, 1, []byte("val1"))
    }); err != nil {
    log.Fatal(err)
}

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet1"
        key := []byte("key1")
        return tx.ZAdd(bucket, key, 2, []byte("val2"))
    }); err != nil {
    log.Fatal(err)
}

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet1"
        key := []byte("key1")
        return tx.ZAdd(bucket, key, 3, []byte("val3"))
    }); err != nil {
    log.Fatal(err)
}

if err := db.View(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet1"
        key := []byte("key1")
        nodes, err := tx.ZRangeByRank(bucket, key, 1, 3)
        if err != nil {
            return err
        }
        for _, node := range nodes {
            fmt.Println("item:", string(node.Value), node.Score)
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}
ZRangeByScore Returns all the elements in the sorted set specified by key in a bucket with a score between min and max. And the parameter Opts is the same as ZCount's. 
if err := db.Update(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet1"
        key := []byte("key1")
        return tx.ZAdd(bucket, key, 70, []byte("val1"))
    }); err != nil {
    log.Fatal(err)
}

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet1"
        key := []byte("key1")
        return tx.ZAdd(bucket, key, 90, []byte("val2"))
    }); err != nil {
    log.Fatal(err)
}

if err := db.Update(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet1"
        key := []byte("key1")
        return tx.ZAdd(bucket, key, 86, []byte("val3"))
    }); err != nil {
    log.Fatal(err)
}

if err := db.View(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet1"
        key := []byte("key1")
        nodes, err := tx.ZRangeByScore(bucket, key, 80, 100, nil)
        if err != nil {
            return err
        }
        for _, node := range nodes {
            fmt.Println("item:", string(node.Value), node.Score)
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}
ZRank Returns the rank of member in the sorted set specified by key in a bucket, with the scores ordered from low to high. 
if err := db.View(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet1"
        key := []byte("key1")
        rank, err := tx.ZRank(bucket, key, []byte("val1"))
        if err != nil {
            return err
        }
        fmt.Println("val1 ZRank :", rank)
        return nil
    }); err != nil {
    log.Fatal(err)
}

if err := db.View(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet1"
        key := []byte("key1")
        rank, err := tx.ZRank(bucket, key, []byte("val2"))
        if err != nil {
            return err
        }
        fmt.Println("val2 ZRank :", rank)
        return nil
    }); err != nil {
    log.Fatal(err)
}

if err := db.View(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet1"
        key := []byte("key1")
        rank, err := tx.ZRank(bucket, key, []byte("val3"))
        if err != nil {
            return err
        }
        fmt.Println("val3 ZRank :", rank)
        return nil
    }); err != nil {
    log.Fatal(err)
}
ZRevRank Returns the rank of member in the sorted set specified by key in a bucket, with the scores ordered from high to low. 
if err := db.View(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet1"
        key := []byte("key1")
        rank, err := tx.ZRank(bucket, key, []byte("val1"))
        if err != nil {
            return err
        }
        fmt.Println("ZRevRank val1 rank:", rank) // ZRevRank key1 rank: 3
        return nil
    }); err != nil {
    log.Fatal(err)
}
if err := db.View(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet1"
        key := []byte("key1")
        rank, err := tx.ZRank(bucket, key, []byte("val2"))
        if err != nil {
            return err
        }
        fmt.Println("ZRevRank val2 rank:", rank) // ZRevRank key2 rank: 2
        return nil
    }); err != nil {
    log.Fatal(err)
}
if err := db.View(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet1"
        key := []byte("key1")
        rank, err := tx.ZRank(bucket, key, []byte("val3"))
        if err != nil {
            return err
        }
        fmt.Println("ZRevRank val3 rank:", rank) // ZRevRank key3 rank: 1
        return nil
    }); err != nil {
    log.Fatal(err)
}
ZRem Removes the member with the lowest score in the sorted set specified by key in a bucket. 
if err := db.Update(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet1"
        key := []byte("key1")
        return tx.ZRem(bucket, key, []byte("val3"))
    }); err != nil {
    log.Fatal(err)
}

if err := db.View(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet1"
        key := []byte("key1")
        nodes, err := tx.ZMembers(bucket, key)
        if err != nil {
            return err
        }
        fmt.Println("after ZRem key1, ZMembers nodes")
        for node := range nodes {
            fmt.Println("item:", node.Score, string(node.Value))
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}
ZRemRangeByRank Removes all elements in the sorted set stored specified by key in a bucket with rank between start and end. The rank is 1-based integer. Rank 1 means the first node; Rank -1 means the last node. 
if err := db.Update(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet1"
        key := []byte("key1")
        return tx.ZRemRangeByRank(bucket, key, 1, 2)
    }); err != nil {
    log.Fatal(err)
}

if err := db.View(
    func(tx *nutsdb.Tx) error {
        bucket := "myZSet1"
        key := []byte("key1")
        nodes, err := tx.ZMembers(bucket, key)
        if err != nil {
            return err
        }
        fmt.Println("after ZRemRangeByRank, ZMembers nodes is", len(nodes))
        for node := range nodes {
            fmt.Println("item:", node.Score, string(node.Value))
        }
        return nil
    }); err != nil {
    log.Fatal(err)
}