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https://issues.apache.org/jira/browse/CASSANDRA-18796?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17760516#comment-17760516
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Caleb Rackliffe commented on CASSANDRA-18796:
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Two questions here: defaults and whether to have a separate guardrail for
allowing non-partition-restricted queries.
On the defaults, we should have a fail threshold by default, even if it's
comically high. I would be perfectly fine w/ 32 (warn) & 1024 (fail). The
former is enough breathing room to do reasonable things, and the latter almost
certainly means you're doing something you shouldn't, and "doing something you
almost certainly shouldn't" is a pretty strong argument for not allowing that
thing by default. (99% of the time this is probably going to mean you're doing
a global query w/ LCS or LCS-like UCS.)
I'd like to have a separate guardrail for non-partition-restricted queries,
even if we leave it permissive by default (which is fine w/ me). It addresses a
different problem than the local "number of SSTable indexes I have to query"
thresholds, and I don't want zero to arbitrarily mean "fail certain kinds of
queries globally". Having mentioned that, though, the warn threshold should
only accept positive values...
> Optionally fail when a non-partition-restricted query is issued against a
> storage-attached index with a backing table using LCS
> -------------------------------------------------------------------------------------------------------------------------------
>
> Key: CASSANDRA-18796
> URL: https://issues.apache.org/jira/browse/CASSANDRA-18796
> Project: Cassandra
> Issue Type: Improvement
> Components: Feature/2i Index, Feature/SAI, Local/Compaction/LCS
> Reporter: Caleb Rackliffe
> Assignee: Caleb Rackliffe
> Priority: Normal
> Fix For: 5.0.x, 5.x
>
>
> With LCS, we will have potentially thousands of SSTables for a given user
> table. Storage-attached also means SSTable-attached, and searching thousands
> of attached indexes is not going to scale well at all locally, due to the
> sheer number of searches and amount of postings list merging involved. We
> should have a guardrail to prohibit this by default.
> Partition-restricted queries, the use-case SAI is broadly designed for,
> should be very efficient.
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