Cassandra guardrails

Hyper-Converged Database is a self-managed database powered by Apache Cassandra®, an open-source NoSQL distributed database. To ensure high availability and optimum performance, Hyper-Converged Database databases have guardrails on underlying Cassandra functionality.

Replication within regions

Hyper-Converged Database databases replicate data across three availability zones within the launched region to promote uptime and ensure data integrity.

Limited functions

Parameter Limit Notes

Large partition

Warning

A warning is issued if reading or compacting a partition that exceeds 100 MB.

Lists

Fixed

Cannot UPDATE or DELETE a list value by index because Hyper-Converged Database does not allow list operations that perform a read-before-write.

UPDATE and DELETE operations that are not by index work normally.

Page size

Fixed

Hyper-Converged Database configures the proper page size automatically.

User-defined functions (UDFs) and user-defined aggregate functions (UDAs)

Disabled

Hyper-Converged Database does support UDFs and UDAs, but they must be enabled in the cassandra.yaml file.

Ignored values

If you try to use a CQL command with unsupported data definition language (DDL) properties, the command works, but ignores the unsupported values.

For example:

CREATE TABLE IF NOT EXISTS library.books
  (
    id UUID PRIMARY KEY,
    lastname text,
    firstname text)
  WITH nodesync={'enabled': 'true'};

The table is created with the defined attributes, except for the nodesync values. The results show a warning that lists the unsupported values, which are ignored:

Warnings :
The unsupported 'nodesync' table option was ignored.

Unsupported CQL commands

Operations concerning search indexes and row-level access control are not supported. This affects the following CQL commands, which are not supported in Hyper-Converged Database:

  • CREATE SEARCH INDEX

  • DROP SEARCH INDEX

  • ALTER SEARCH INDEX CONFIG

  • ALTER SEARCH INDEX SCHEMA

  • COMMIT SEARCH INDEX

  • REBUILD SEARCH INDEX

  • RELOAD SEARCH INDEX

  • RESTRICT ROWS

  • UNRESTRICT ROWS

For a list of supported CQL commands, see the CQL quick reference.

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