Amazon DocumentDB serverless instance limits
For DocumentDB serverless instances, the following limits per instance are dependent upon the instance’s current scaling capacity:
Instance Memory (GiB)
Connections (all)
Cursor Limit
Open Transactions
Connections (active)
The following tables describe how the per-instance limits of serverless instances scale in relation to the instance’s current scaling capacity.
Note that the limit values are different depending on whether the cluster’s MinCapacity scaling configuration has been set to greater than two (2).
If MinCapacity is set to less than or equal to 2, then the limit values for cursor limit, open transactions, and connections (active) are capped to a lower maximum value.
(The technical reason for the cap is to support scaling down to an “idle” state.
For more information, see Idle state (0.5 DCUs).
db.serverless instance limits if MinCapacity ≤1
| Current Capacity (DCU) | Instance Memory (GiB) | Connections (all) | Cursor Limit | Open Transactions | Connections (active) |
|---|---|---|---|---|---|
|
0.5 |
1 |
250 |
6 |
12 |
39 |
|
1 |
2 |
500 |
12 |
24 |
79 |
|
2 |
4 |
1000 |
24 |
48 |
173 |
|
4 |
8 |
2000 |
48 |
96 |
416 |
|
8 |
16 |
4000 |
96 |
192 |
1071 |
|
16 |
32 |
8000 |
132 |
264 |
1550 |
|
32 |
64 |
16000 |
132 |
264 |
1550 |
|
64 |
128 |
32000 |
132 |
264 |
1550 |
|
128 |
256 |
60000 |
132 |
264 |
1550 |
|
256 |
512 |
60000 |
132 |
264 |
1550 |
db.serverless instance limits if MinCapacity >1
| Current Capacity (DCU) | Instance Memory (GiB) | Connections (all) | Cursor Limit | Open Transactions | Connections (active) |
|---|---|---|---|---|---|
|
1.5 |
3 |
7250 |
18 |
36 |
124 |
|
2 |
4 |
1000 |
24 |
48 |
173 |
|
4 |
8 |
2000 |
48 |
96 |
416 |
|
8 |
16 |
4000 |
96 |
192 |
1071 |
|
16 |
32 |
8000 |
192 |
384 |
2709 |
|
32 |
64 |
16000 |
384 |
768 |
4500 |
|
64 |
128 |
32000 |
768 |
1536 |
4500 |
|
128 |
256 |
60000 |
1536 |
3072 |
4500 |
|
256 |
512 |
60000 |
3072 |
6144 |
4500 |
You can monitor and alarm on the per instance limits using the following CloudWatch metrics. For more on Amazon DocumentDB CloudWatch metrics, see Monitoring Amazon DocumentDB with CloudWatch.
| Resource | CloudWatch limit metric | CloudWatch usage metric (1-min. max) | CloudWatch usage metric |
|---|---|---|---|
| Instance Memory | - | - | FreeableMemory |
| Connections (all) | DatabaseConnectionsLimit | DatabaseConnectionsMax | DatabaseConnections |
| Cursors | DatabaseCursorsLimit | DatabaseCursorsMax | DatabaseCursors |
| Transactions | TransactionsOpenLimit | TransactionsOpenMax | TransactionsOpen |