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https://issues.apache.org/jira/browse/SPARK-60228?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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L. C. Hsieh updated SPARK-60228:
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Affects Version/s: 4.2.0
4.1.3
4.3.0
4.4.0
(was: 5.0.0)
> Avoid quadratic cache lookups by table name in CacheManager
> -----------------------------------------------------------
>
> Key: SPARK-60228
> URL: https://issues.apache.org/jira/browse/SPARK-60228
> Project: Spark
> Issue Type: Bug
> Components: SQL
> Affects Versions: 4.2.0, 4.3.0, 4.1.3, 4.4.0
> Reporter: L. C. Hsieh
> Priority: Major
>
> SPARK-54004 changed CacheManager.isMatchedTableOrView to match on
> EliminateSubqueryAliases(plan), which rewrites the whole tree. The check is
> evaluated on every node of every cached plan (via plan.exists) when uncaching
> or recaching by table name, so each scan rewrites every subtree of every
> cached plan. The cost grows super-linearly with the cached plan depth, times
> the number of cache entries.
> The by-name scan runs on every DSv2 write (refreshCache ->
> recacheTableOrView) and on DDL such as DROP / CREATE OR REPLACE / ALTER VIEW.
> Measured locally for a by-name scan matching no entry, with 10 cached plans
> of 1000 chained filters each, a single scan takes about 40 seconds.
> All matched cases only inspect the root node, so only the chain of
> SubqueryAlias nodes at the root needs to be stripped.
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