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https://issues.apache.org/jira/browse/PIG-2205?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13079660#comment-13079660
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Dmitriy V. Ryaboy commented on PIG-2205:
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It used to be that something like the script below was thrown out by the parser:
{code}
filtered = filter my_relation by my_relation.x > 2;
{code}
We now try to actually evaluate that, treating my_relation as a scalar to be
loaded up while iterating over my_relation.
We should instead suggest that the user probably wanted to write
{code}
filtered = filter my_relation by x > 2;
{code}
A similar problems occurs in this code:
{code}
joined = join a by id, b by id;
projected = foreach joined generate a.id;
{code}
Naturally, the user actually meant
{code}
projected = foreach joined generate a::id;
{code}
Instead of erroring out, we currently generate massive plans that involve lots
of splits (I saw a 5-line script filled with this syntax mistake generate 12
jobs!), and fail eventually with "Scalar has more than one row in the output"
-- which doesn't help a user who is not advanced enough to know about Scalars.
This is extra confusing to people coming from a SQL background, who are of
course extremely used to referring to their tables' fields this way.
> Improve error checking around Scalar functionality
> --------------------------------------------------
>
> Key: PIG-2205
> URL: https://issues.apache.org/jira/browse/PIG-2205
> Project: Pig
> Issue Type: Improvement
> Reporter: Dmitriy V. Ryaboy
>
> The scalar-loading feature added in 0.8 has caused a new class of user
> problems to show up, when they use the "foo.bar" syntax incorrectly.
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