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https://issues.apache.org/jira/browse/SPARK-16203?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16551885#comment-16551885
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Nick Nicolini edited comment on SPARK-16203 at 7/22/18 3:21 AM:
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[~srowen] [~hvanhovell] I want to re-open this discussion. I've recently hit
many cases of regexp parsing where we need to match on something that is always
arbitrary in length; for example, a text block that looks something like:
{code:java}
AAA:WORDS|
BBB:TEXT|
MSG:ASDF|
MSG:QWER|
...
MSG:ZXCV|{code}
Where I need to pull out all values between "MSG:" and "|", which can occur in
each instance between 1 and n times. I cannot reliably use the method shown
above, and while I can write a UDF to handle this it'd be great if this was
supported natively in Spark.
Perhaps we can implement something like "regexp_extract_all" as
[Presto|https://prestodb.io/docs/current/functions/regexp.html] and
[Pig|https://pig.apache.org/docs/latest/api/org/apache/pig/builtin/REGEX_EXTRACT_ALL.html]
have?
was (Author: nnicolini):
[~srowen] [~hvanhovell] I want to re-open this discussion. I've recently hit
many cases of regexp parsing where we need to match on something that is always
arbitrary in length; for example, a text block that looks something like:
{code:java}
AAA:WORDS|
BBB:TEXT|
MSG:ASDF|
MSG:QWER|
...
MSG:ZXCV|{code}
Where I need to pull out all values between "MSG:" and "|", which can occur in
each instance between 1 and n times. I cannot reliably use the method shown
above, and while I can write a UDF to handle this it'd be great if this was
supported natively in Spark.
Perhaps we can implement something like "regexp_extract_all" as
[Presto|https://prestodb.io/docs/current/functions/regexp.html] and
[Pig|https://pig.apache.org/docs/latest/api/org/apache/pig/builtin/REGEX_EXTRACT_ALL.html]
have?
> regexp_extract to return an ArrayType(StringType())
> ---------------------------------------------------
>
> Key: SPARK-16203
> URL: https://issues.apache.org/jira/browse/SPARK-16203
> Project: Spark
> Issue Type: Improvement
> Affects Versions: 2.0.0
> Reporter: Max Moroz
> Priority: Minor
>
> regexp_extract only returns a single matched group. If (as if often the case
> - e.g., web log parsing) we need to parse the entire line and get all the
> groups, we'll need to call it as many times as there are groups.
> It's only a minor annoyance syntactically.
> But unless I misunderstand something, it would be very inefficient. (How
> would Spark know not to do multiple pattern matching operations, when only
> one is needed? Or does the optimizer actually check whether the patterns are
> identical, and if they are, avoid the repeated regex matching operations??)
> Would it be possible to have it return an array when the index is not
> specified (defaulting to None)?
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