[CASSANDRA-2025] generalized way of expressing hierarchical values

• Type: Sub-task
• Status: Resolved
• Priority: Low
• Resolution: Fixed
• Fix Version/s: 0.8 beta 1
• Component/s: Legacy/CQL
• Labels: cql
• Assignee: Eric Evans
• Reporter: Eric Evans

Authors

Eric Evans

• Created: 21/Jan/11 19:57
• Updated: 16/Apr/19 09:33
• Resolved: 25/Feb/11 21:40

Description

While hashing out CREATE KEYSPACE, it became obvious that we needed a syntax for expressing hierarchical values. Properties like replication_factor can be expressed simply using keyword arguments like (replication_factor = 3), but strategy_options is a map of strings.

The solution I took in CASSANDRA-1709 was to dot-delimit "map name" and option key, so for example:

CREATE KEYSPACE keyspace WITH ... AND strategy_options.DC1 = "1" ...

This led me to wonder if this was a general enough approach for any future cases that might come up. One example might be compound/composite column names. Dot-delimiting is a bad choice here since it rules out ever introducing a float literal.

One suggestion would be to colon-delimit, so for example:

CREATE KEYSPACE keyspace WITH ... AND strategy_options:DC1 = "1" ...

Or in the case of composite column names:

SELECT columnA:columnB,column1:column2 FROM Standard2 USING CONSISTENCY.QUORUM WHERE KEY = key;
UPDATE Standard2 SET columnA:columnB = valueC, column1:column2 = value3 WHERE KEY = key;

As an aside, this also led me to the conclusion that CONSISTENCY.<LEVEL> is probably a bad choice for consistency level specification. It mirrors the underlying enum for no good reason and should probably be changed to CONSISTENCY <LEVEL> (i.e. omitting the separator). For example:

SELECT column FROM Standard2 USING CONSISTENCY QUORUM WHERE KEY = key;

Thoughts?

Edit: improved final example

Edit: restore final example, create new one (gah).