英文:
etcd3 Go Client - How to paginate large sets of keys?
问题
似乎在处理大量键的分页时，需要使用WithFromKey()和WithLimit()选项来进行Get()操作。例如，如果我想获取2页共10个项目，可以这样做：
opts := []clientv3.OpOption {
clientv3.WithPrefix(),
clientv3.WithSort(clientv3.SortByKey, clientv3.SortAscend),
clientv3.WithLimit(10),
}
gr, err := kv.Get(ctx, "key", opts...)
if err != nil {
log.Fatal(err)
}
fmt.Println("--- 第一页 ---")
for _, item := range gr.Kvs {
fmt.Println(string(item.Key), string(item.Key))
}
lastKey := string(gr.Kvs[len(gr.Kvs)-1].Value)
fmt.Println("--- 第二页 ---")
opts = append(opts, clientv3.WithFromKey())
gr, _ = kv.Get(ctx, lastKey, opts...)
// 跳过第一个项目，即前一个Get的最后一个项目
for _, item := range gr.Kvs[1:] {
fmt.Println(string(item.Key), string(item.Value))
}
问题在于最后一个键再次作为第二页的第一个项目被获取到，我需要跳过它，只获取9个新项目。
这是正确的分页方式吗？还是我漏掉了什么？
英文:
It seems that pagination through a large set of keys involve using WithFromKey() and WithLimit() options to Get(). For example if I want to fetch 2 pages of 10 items I would do something like:
opts := []clientv3.OpOption {
clientv3.WithPrefix(),
clientv3.WithSort(clientv3.SortByKey, clientv3.SortAscend),
clientv3.WithLimit(10),
}
gr, err := kv.Get(ctx, "key", opts...)
if err != nil {
log.Fatal(err)
}
fmt.Println("--- First page ---")
for _, item := range gr.Kvs {
fmt.Println(string(item.Key), string(item.Key))
}
lastKey := string(gr.Kvs[len(gr.Kvs)-1].Value)
fmt.Println("--- Second page ---")
opts = append(opts, clientv3.WithFromKey())
gr, _ = kv.Get(ctx, lastKey, opts...)
// Skipping the first item, which the last item from from the previous Get
for _, item := range gr.Kvs[1:] {
fmt.Println(string(item.Key), string(item.Value))
}
The problem is that the last key is fetched agains as the first item of the second page, which I need to skip and only 9 new items.
Is that the proper way to paginate or am I missing something?
答案1
得分: 1
在查看以下的clientv3代码时，下一个键可以通过在最后一个键后面添加0x00来计算。
https://github.com/coreos/etcd/blob/88acced1cd7ad670001d1280b97de4fe7b647687/clientv3/op.go#L353
话虽如此，我更喜欢忽略第一个键，从第二个和后续页面开始。
英文:
Looking at the following clientv3 code, the next key can be computed by appending 0x00 to the last key.
https://github.com/coreos/etcd/blob/88acced1cd7ad670001d1280b97de4fe7b647687/clientv3/op.go#L353
That said, I prefer ignoring the first key from the 2nd and following pages.
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