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https://issues.apache.org/jira/browse/CASSANDRA-19560?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Stefan Miklosovic updated CASSANDRA-19560:
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Change Category: Operability
Complexity: Normal
Fix Version/s: 5.x
Status: Open (was: Triage Needed)
> Implement support for virtual types
> -----------------------------------
>
> Key: CASSANDRA-19560
> URL: https://issues.apache.org/jira/browse/CASSANDRA-19560
> Project: Cassandra
> Issue Type: New Feature
> Components: Feature/Virtual Tables
> Reporter: Stefan Miklosovic
> Assignee: Stefan Miklosovic
> Priority: Normal
> Fix For: 5.x
>
>
> We can not use user types in virtual tables. While it might look strange at
> first to ask for the support of this, currently we can not do something like
> this:
> {code}
> cqlsh> select * from system_guardrails.thresholds ;
> name | value
> -------------------------------+----------------------
> collection_size | {warn: 0, fail: 0}
> column_value_size | {warn: -1, fail: -1}
> columns_per_table | {warn: -1, fail: -1}
> ...
> {code}
> {code}
> VIRTUAL TABLE system_guardrails.thresholds (
> name text PRIMARY KEY,
> value settings
> ) WITH comment = 'Guardrails configuration table for thresholds';
> {code}
> because "settings" is a UDT
> {code}
> cqlsh> DESCRIBE type system_guardrails.settings ;
> CREATE TYPE system_guardrails.settings (
> warn bigint,
> fail bigint
> );
> {code}
> While this is not absolutely necessary to implement and it might be worked
> around by a simple tuple, it feels sad that user experience suffers.
> Supporting custom types for vtables is indeed possible so we should just do
> that.
> There is additional work needed to do this, because virtual types are not
> supported in python-driver, I had to do this:
> https://github.com/smiklosovic/python-driver/commit/14b236bb471bc4a7e251a9f6b694de7885b339de
> python-driver reads system_schema.types in order to show the correct output
> in cqlsh, as it has not recognized virtual types, it was alwasy displaying
> the results like
> {code}
> settings(warn=-1, fail -1)
> {code}
> because it could not evaluate it differently.
> With the patch for python-driver, it will fetch it from
> system_virtual_schema.types, where it is like:
> {code}
> cqlsh> select * from system_virtual_schema.types ;
> keyspace_name | type_name | field_names | field_types
> -------------------+-----------+------------------+----------------------
> system_guardrails | settings | ['warn', 'fail'] | ['bigint', 'bigint']
> (1 rows)
> {code}
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