Quotas and limits in Amazon QLDB - Amazon Quantum Ledger Database (Amazon QLDB)

Quotas and limits in Amazon QLDB

This section describes the current quotas, also referred to as limits, in Amazon QLDB.

Default quotas

QLDB has the following default quotas, as also listed at Amazon QLDB endpoints and quotas in the AWS General Reference. These quotas are per AWS account per Region. To request a quota increase for your account in a Region, use the Service Quotas console.

Open the Service Quotas console at https://console.aws.amazon.com/servicequotas/.

Resource Default quota
The maximum number of active ledgers that you can create in this account in the current Region 5
The maximum number of active journal exports to Amazon S3 per ledger 2
The maximum number of active journal streams to Kinesis Data Streams per ledger 5

Fixed quotas

In addition to default quotas, QLDB has the following fixed quotas per ledger. These quotas cannot be increased by using Service Quotas:

Resource Fixed quota
Number of concurrent active sessions 1500
Number of active tables 20
Number of total tables (active and inactive)
Note

In QLDB, dropped tables are considered inactive and count against this total quota.

40
Number of indexes per table 5
Number of documents in a transaction 40
Document size 128 KB
Transaction size 4 MB
Transaction timeout 30 seconds
Expiration period for completed journal export jobs 7 days
Expiration period for terminal journal streams 7 days

Transaction size

The maximum size for a transaction in QLDB is 4 MB. The size of a transaction is calculated based on the sum of the following factors.

Deltas

The document changes that are generated by all the statements within the transaction. In a transaction that impacts several documents, the total delta size is the sum of each affected document's individual delta.

Metadata

The QLDB-generated transaction metadata that is associated with each affected document.

Indexes

If an index is defined on a table that is affected by the transaction, the associated index entry also generates a delta.

History

Because all document revisions are persisted in QLDB, all transactions also append to the history.

Inserts—Every document inserted into a table also has a copy inserted into its history table. For example, a newly inserted 100 KB document generates a minimum of 200 KB of deltas in a transaction. (This is a rough estimate that does not include metadata or indexes.)

Updates—Any document update, even for a single field, creates a new revision of the entire document in history, plus or minus the delta of the update. This means that a small update in a large document would still generate a large transaction delta. For example, adding 2 KB of data in an existing 100 KB document creates a new 102 KB revision in history. This adds up to at least 104 KB of total deltas in a transaction. (Again, this estimate does not include metadata or indexes.)

Deletes—Similar to updates, any delete transaction creates a new document revision in the history. However, the newly created DELETE revision is smaller than the original document because it has null user data and only contains metadata.

Naming constraints

The following table describes naming constraints within Amazon QLDB.

Ledger name

Journal stream name

  • Must only contain 1–32 alphanumeric characters or hyphens.

  • Must not be all numbers.

  • Can't contain two consecutive hyphens.

  • The first and last characters must be a letter or number.

  • The ledger names are case sensitive.

Table name

  • Must only contain 1–128 alphanumeric characters or underscores.

  • The first character must be a letter or an underscore.

  • The remaining characters can be any combination of alphanumeric characters and underscores.

  • The table names are case sensitive.

  • Must not be a QLDB PartiQL reserved word.