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From "Cheng Lian (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (SPARK-19737) New analysis rule for reporting unregistered functions without relying on relation resolution
Date Sat, 25 Feb 2017 06:20:44 GMT

     [ https://issues.apache.org/jira/browse/SPARK-19737?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Cheng Lian updated SPARK-19737:
-------------------------------
    Description: 
Let's consider the following simple SQL query that reference an invalid function {{foo}} that
is never registered in the function registry:
{code:sql}
SELECT foo(a) FROM t
{code}
Assuming table {{t}} is a partitioned  temporary view consisting of a large number of files
stored on S3, then it may take the analyzer a long time before realizing that {{foo}} is not
registered yet.

The reason is that the existing analysis rule {{ResolveFunctions}} requires all child expressions
to be resolved first. Therefore, {{ResolveRelations}} has to be executed first to resolve
all columns referenced by the unresolved function invocation. This further leads to partition
discovery for {{t}}, which may take a long time.

To address this case, we propose a new lightweight analysis rule {{LookupFunctions}} that
# Matches all unresolved function invocation
# Look up the function name from the function registry
# Report analysis error for any unregistered functions

Since this rule doesn't actually try to resolve the unresolved functions, it doesn't rely
on {{ResolveRelations}} and therefore doesn't trigger partition discovery.

We may put this analysis rule in a separate {{Once}} rule batch that sits between the "Substitution"
batch and the "Resolution" batch to avoid running it repeatedly and make sure it gets executed
before {{ResolveRelations}}.

  was:
Let's consider the following simple SQL query that reference an invalid function {{foo}} that
is never registered in the function registry:
{code:sql}
SELECT foo(a) FROM t
{code}
Assuming table {{t}} is a partitioned  temporary view consisting of a large number of files
stored on S3, then it may take the analyzer a long time before realizing that {{foo}} is not
registered yet.

The reason is that the existing analysis rule {{ResolveFunctions}} requires all child expressions
to be resolved first. Therefore, {{ResolveRelations}} has to be executed first to resolve
all columns referenced by the unresolved function invocation. This further leads to partition
discovery for {{t}}, which may take a long time.

To address this case, we propose a new lightweight analysis rule {{LookupFunctions}} that
# Matches all unresolved function invocation
# Look up the function name from the function registry
# Report analysis error for any unregistered functions

Since this rule doesn't try to actually resolve the unresolved functions, it doesn't rely
on {{ResolveRelations}} and therefore doesn't trigger partition discovery.

We may put this analysis rule in a separate {{Once}} rule batch that sits between the "Substitution"
batch and the "Resolution" batch to avoid running it repeatedly.


> New analysis rule for reporting unregistered functions without relying on relation resolution
> ---------------------------------------------------------------------------------------------
>
>                 Key: SPARK-19737
>                 URL: https://issues.apache.org/jira/browse/SPARK-19737
>             Project: Spark
>          Issue Type: Bug
>          Components: SQL
>    Affects Versions: 2.2.0
>            Reporter: Cheng Lian
>             Fix For: 2.2.0
>
>
> Let's consider the following simple SQL query that reference an invalid function {{foo}}
that is never registered in the function registry:
> {code:sql}
> SELECT foo(a) FROM t
> {code}
> Assuming table {{t}} is a partitioned  temporary view consisting of a large number of
files stored on S3, then it may take the analyzer a long time before realizing that {{foo}}
is not registered yet.
> The reason is that the existing analysis rule {{ResolveFunctions}} requires all child
expressions to be resolved first. Therefore, {{ResolveRelations}} has to be executed first
to resolve all columns referenced by the unresolved function invocation. This further leads
to partition discovery for {{t}}, which may take a long time.
> To address this case, we propose a new lightweight analysis rule {{LookupFunctions}}
that
> # Matches all unresolved function invocation
> # Look up the function name from the function registry
> # Report analysis error for any unregistered functions
> Since this rule doesn't actually try to resolve the unresolved functions, it doesn't
rely on {{ResolveRelations}} and therefore doesn't trigger partition discovery.
> We may put this analysis rule in a separate {{Once}} rule batch that sits between the
"Substitution" batch and the "Resolution" batch to avoid running it repeatedly and make sure
it gets executed before {{ResolveRelations}}.



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