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https://issues.apache.org/jira/browse/SPARK-11012?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Cheng Lian updated SPARK-11012:
-------------------------------
Description:
In SPARK-10337, we added the first step of supporting view natively, which is
basically wrapping the original view definition SQL text with an extra
{{SELECT}} and then store the wrapped SQL text into metastore. This approach
suffers at least two issues:
# Switching current database may break view queries
# HiveQL doesn't allow CTE as subquery, thus CTE can't be used in view
definition
To fix these issues, we need to canonicalize the view definition. For example,
for a SQL string
{code:sql}
SELECT a, b FROM table
{code}
we will save this text to Hive metastore as
{code:sql}
SELECT `table`.`a`, `table`.`b` FROM `currentDB`.`table`
{code}
The core infrastructure of this work is SQL query string generation
(SPARK-12593). Namely, converting resolved logical query plans back to
canonicalized SQL query strings. [PR
#10541|https://github.com/apache/spark/pull/10541] set up basic infrastructure
of SQL generation, but more language structures need to be supported.
was:In SPARK-10337, we added the first step of supporting view natively.
Building on top of that work, we need to canonicalize the view definition. So,
for a SQL string SELECT a, b FROM table, we will save this text to Hive
metastore as SELECT `table`.`a`, `table`.`b` FROM `currentDB`.`table`.
> Canonicalize view definitions
> -----------------------------
>
> Key: SPARK-11012
> URL: https://issues.apache.org/jira/browse/SPARK-11012
> Project: Spark
> Issue Type: New Feature
> Components: SQL
> Affects Versions: 2.0.0
> Reporter: Yin Huai
>
> In SPARK-10337, we added the first step of supporting view natively, which is
> basically wrapping the original view definition SQL text with an extra
> {{SELECT}} and then store the wrapped SQL text into metastore. This approach
> suffers at least two issues:
> # Switching current database may break view queries
> # HiveQL doesn't allow CTE as subquery, thus CTE can't be used in view
> definition
> To fix these issues, we need to canonicalize the view definition. For
> example, for a SQL string
> {code:sql}
> SELECT a, b FROM table
> {code}
> we will save this text to Hive metastore as
> {code:sql}
> SELECT `table`.`a`, `table`.`b` FROM `currentDB`.`table`
> {code}
> The core infrastructure of this work is SQL query string generation
> (SPARK-12593). Namely, converting resolved logical query plans back to
> canonicalized SQL query strings. [PR
> #10541|https://github.com/apache/spark/pull/10541] set up basic
> infrastructure of SQL generation, but more language structures need to be
> supported.
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