System Limits

This topic specifies maximum sizes and numbers of various SingleStoreDB components. Use the following links to navigate to a section below:

Cluster-Level Limits

Item

Max Spec (enforced)

Max Spec (recommended)

Comments

Number of hosts in a cluster

None

Workloads that generate significant network traffic between hosts should be limited to clusters with smaller number of hosts.

Number of nodes in a cluster (includes leaves and aggregators)

None

Workloads that generate significant network traffic between nodes should be limited to clusters with smaller number of nodes.

Number of databases in a cluster

None

Each database requires memory for transaction buffer and more databases implies greater demand on available memory.

Concurrent queries in a cluster

None

Each aggregator will only actually execute a limited number of queries at once (defined by max_connection_threads, default 192). Beyond that concurrency, queries will be queued up.

Simultaneous client connections

100,000 per aggregator

For more information, read about max_connections

Database-Level Limits

Item

Max Spec (enforced)

Max Spec (recommended)

Comments

Number of tables in a database

Each table costs some per-table memory overhead.

Number of partitions in a cluster

None

Number of database partitions per node

2414

Table-Level Limits

Item

Max Spec (enforced)

Max Spec (recommended)

Comments

Number of columns per table

4096

Row size in bytes

64KB *

Limit does not apply to variable-length strings such as VARCHAR, VARBINARY, TEXT, etc.

Length of names in characters (applies to table names, column names)

64

Number of indexes per table

63

Number of columns per index

32

Number of tables in a join for each SELECT

253

* The number of fields that will fit in the 64KB maximum row size is determined by the field types and how rows are laid out in the in-memory rowstore format. In some cases, writes (inserts and updates) to columnstore tables are implemented by storing the newly written rows in a rowstore format before flushing them to the column-oriented format. The row size limit applies to fixed-width data which includes a 4-byte nullability flag for nullable fields. The row size limit does not include the body of variable-width fields, but only the in-row portion, which includes an 8-byte memory location pointer and an optional 4-byte nullability flag. The sum of the in-row data size for all columns cannot exceed 64KB."

Naming Constraints

Item

Constraints

General

  • Maximum length is 64 characters unless specified otherwise below.

  • Name cannot be blank.

  • Name cannot end with a space.

Database names

Database names can only contain alphanumeric characters and underscores, and cannot start with a digit.

Table names

Table names can contain both alphanumeric and non-alphanumeric characters, but cannot contain the / character.

Other database objects (stored procedures, views, user-defined functions, user-defined aggregate functions, and table-valued functions)

Maximum length of 64 characters.

User names

Maximum length of 32 characters.

Role names

No length limit. Cannot contain commas or spaces.

Group names

No length limit. Cannot contain commas or spaces.

Last modified: December 9, 2022

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