# Error failed when calling List.rollup

**URL:** <https://discuss.dgraph.io/t/error-failed-when-calling-list-rollup/15453>\
**Category:** Dgraph\
**Created:** [September 1, 2021, 9:50am UTC](https://discuss.dgraph.io/t/error-failed-when-calling-list-rollup/15453 "2021-09-01T09:50:26Z")\
**Posts on this page:** 5\
**Page:** 1

<div class="post-metadata">

**Author:** ![Timothy\_Sleptsov](https://yyz1.discourse-cdn.com/flex007/user_avatar/discuss.dgraph.io/timothy_sleptsov/32/7310_2.png) [@Timothy\_Sleptsov](https://discuss.dgraph.io/u/Timothy_Sleptsov)\
**Post date:** [September 1, 2021, 9:50am UTC](https://discuss.dgraph.io/t/error-failed-when-calling-list-rollup/15453/1 "2021-09-01T09:50:26Z")

</div>

Hi! I want to upload ~15GB gzipped rdf files To local Dgraph cluster which contain one zero and 3 alpha (all alpha located on same volume, and running in ludicrous mode). Everything run on one AWS instance r5a.24xlarge, 768 GB RAM, 2TB SSD, 96 cores. Dgraph version : v21.03.1

I am using dgraph live loader for this purpose, and I perform upload in several steps. I successfully uploaded ~5 GB of data, but after it I start to see in log of one alpha(s) a lot of error messages like that:

```auto
W0901 08:43:08.025933 343110 mvcc.go:148] Error failed when calling List.rollup: while encoding: cannot iterate through the list: cannot initialize iterator when calling List.iterate: cannot read initial list part for list with base key 00000000000000000000066c696e6b6564000000000000694b24: could not read list part with key 04000000000000000000066c696e6b6564000000000000694b240000000000000001: Key not found rolling up key [0 0 0 0 0 0 0 0 0 0 6 108 105 110 107 101 100 0 0 0 0 0 0 105 75 36]

```

And when I tried to perform some query, I also get similar error:

```auto
{
    q(func: type(Bucket)) @filter(eq(period, "hour")) @groupby(timestamp) {
  }
}' | jq
{
  "errors": [
    {
      "message": ": cannot retrieve UIDs from list with key 000000000000000000000b6467726170682e7479706502024275636b6574: cannot initialize iterator when calling List.iterate: cannot read initial list part for list with base key 000000000000000000000b6467726170682e7479706502024275636b6574: could not read list part with key 040000000000000000000b6467726170682e7479706502024275636b65740000000000000001: Key not found",
      "extensions": {
        "code": "ErrorInvalidRequest"
      }
    }
  ],
  "data": null
}

```

But this query work fine before. I continue to upload data, and when it passed ~13GB, live loader failed with error message:

```auto
[23:11:20Z] Elapsed: 05h22m40s Txns: 265151 N-Quads: 265151000 N-Quads/s [last 5s]: 16400 Aborts: 217
panic: rpc error: code = Unknown desc = cannot retrieve predicate information: No connection exists
goroutine 355 [running]:
github.com/dgraph-io/dgraph/dgraph/cmd/live.(*loader).upsertUids(0xc0004a7200, 0xc04269c000, 0x3e8, 0x3e8)
        /ext-go/1/src/github.com/dgraph-io/dgraph/dgraph/cmd/live/run.go:394 +0xeb3
github.com/dgraph-io/dgraph/dgraph/cmd/live.(*loader).processLoadFile.func1(0xc0004ea5a0, 0xc0004a7200, 0xc00078da10)
        /ext-go/1/src/github.com/dgraph-io/dgraph/dgraph/cmd/live/run.go:552 +0x56e
created by github.com/dgraph-io/dgraph/dgraph/cmd/live.(*loader).processLoadFile
        /ext-go/1/src/github.com/dgraph-io/dgraph/dgraph/cmd/live/run.go:487 +0xa5

```

Any ideas, why suddenly query stop working, and why live loader fail, on such powerful instance, and relative small dataset?

---

<div class="post-metadata">

**Author:** ![MichelDiz](https://yyz1.discourse-cdn.com/flex007/user_avatar/discuss.dgraph.io/micheldiz/32/11873_2.png) [@MichelDiz](https://discuss.dgraph.io/u/MichelDiz)\
**Post date:** [September 1, 2021, 2:18pm UTC](https://discuss.dgraph.io/t/error-failed-when-calling-list-rollup/15453/2 "2021-09-01T14:18:34Z")

</div>

> [@Timothy\_Sleptsov](#):
>
> `@groupby(timestamp)`

What is the timestamp predicate? Group by feature doesn’t work with value edges. Only with relational edges.

---

<div class="post-metadata">

**Author:** ![Timothy\_Sleptsov](https://yyz1.discourse-cdn.com/flex007/user_avatar/discuss.dgraph.io/timothy_sleptsov/32/7310_2.png) [@Timothy\_Sleptsov](https://discuss.dgraph.io/u/Timothy_Sleptsov)\
**Post date:** [September 1, 2021, 6:33pm UTC](https://discuss.dgraph.io/t/error-failed-when-calling-list-rollup/15453/3 "2021-09-01T18:33:37Z")

</div>

timestamp is datetime predicate indexed by hour. Actually I was able groupby on this predicate and count nodes, and on other non uid predicates also.

---

<div class="post-metadata">

**Author:** ![Dave\_Aitel](https://yyz1.discourse-cdn.com/flex007/user_avatar/discuss.dgraph.io/dave_aitel/32/8431_2.png) [@Dave\_Aitel](https://discuss.dgraph.io/u/Dave_Aitel)\
**Post date:** [September 11, 2021, 11:53pm UTC](https://discuss.dgraph.io/t/error-failed-when-calling-list-rollup/15453/4 "2021-09-11T23:53:19Z")

</div>

Has there been a resolution of this? I’m seeing it now too:  
mvcc.go:148] Error failed when calling List.rollup: while encoding:

---

<div class="post-metadata">

**Author:** ![doodler.05](https://avatars.discourse-cdn.com/v4/letter/d/8e8cbc/32.png) [@doodler.05](https://discuss.dgraph.io/u/doodler.05)\
**Post date:** [November 18, 2021, 11:07am UTC](https://discuss.dgraph.io/t/error-failed-when-calling-list-rollup/15453/5 "2021-11-18T11:07:42Z")

</div>

Seeing this as well