[jira] [Commented] (SPARK-40802) Enhance JDBC Connector to use PreparedStatement.getMetaData() to resolve schema instead of PreparedStatement.executeQuery()
[ https://issues.apache.org/jira/browse/SPARK-40802?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17626742#comment-17626742 ] Apache Spark commented on SPARK-40802: -- User 'Mingli-Rui' has created a pull request for this issue: https://github.com/apache/spark/pull/38452 > Enhance JDBC Connector to use PreparedStatement.getMetaData() to resolve > schema instead of PreparedStatement.executeQuery() > --- > > Key: SPARK-40802 > URL: https://issues.apache.org/jira/browse/SPARK-40802 > Project: Spark > Issue Type: Improvement > Components: SQL >Affects Versions: 2.1.0 >Reporter: Mingli Rui >Priority: Major > Original Estimate: 24h > Remaining Estimate: 24h > > Currently, Spark JDBC Connector uses *PreparedStatement.executeQuery()* to > resolve the JDBCRelation's schema. The schema query is like *s"SELECT * FROM > $table_or_query WHERE 1=0".* > But it is not necessary to execute the query. It's enough to *prepare* the > query. With preparing the statement, the query is parsed and compiled, but is > not executed. It will be more efficient. > So, it's better to use PreparedStatement.getMetaData() to resolve schema. -- This message was sent by Atlassian Jira (v8.20.10#820010) - To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org For additional commands, e-mail: issues-h...@spark.apache.org
[jira] [Commented] (SPARK-40802) Enhance JDBC Connector to use PreparedStatement.getMetaData() to resolve schema instead of PreparedStatement.executeQuery()
[ https://issues.apache.org/jira/browse/SPARK-40802?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17626743#comment-17626743 ] Apache Spark commented on SPARK-40802: -- User 'Mingli-Rui' has created a pull request for this issue: https://github.com/apache/spark/pull/38452 > Enhance JDBC Connector to use PreparedStatement.getMetaData() to resolve > schema instead of PreparedStatement.executeQuery() > --- > > Key: SPARK-40802 > URL: https://issues.apache.org/jira/browse/SPARK-40802 > Project: Spark > Issue Type: Improvement > Components: SQL >Affects Versions: 2.1.0 >Reporter: Mingli Rui >Priority: Major > Original Estimate: 24h > Remaining Estimate: 24h > > Currently, Spark JDBC Connector uses *PreparedStatement.executeQuery()* to > resolve the JDBCRelation's schema. The schema query is like *s"SELECT * FROM > $table_or_query WHERE 1=0".* > But it is not necessary to execute the query. It's enough to *prepare* the > query. With preparing the statement, the query is parsed and compiled, but is > not executed. It will be more efficient. > So, it's better to use PreparedStatement.getMetaData() to resolve schema. -- This message was sent by Atlassian Jira (v8.20.10#820010) - To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org For additional commands, e-mail: issues-h...@spark.apache.org
[jira] [Commented] (SPARK-40802) Enhance JDBC Connector to use PreparedStatement.getMetaData() to resolve schema instead of PreparedStatement.executeQuery()
[
https://issues.apache.org/jira/browse/SPARK-40802?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17619124#comment-17619124
]
Mingli Rui commented on SPARK-40802:
Hi, [~hyukjin.kwon], Could you please explain more about +We could probably
introduce a dialect to optimize this further.+ Do you mean let's move
{{JDBCRDD.getQueryOutputSchema}} to a function for JdbcDialect? So that every
concrete Jdbc dialect class has a chance to resolve the schema by their own
way? For example,
{code:java}
abstract class JdbcDialect extends Serializable with Logging {
def getQueryOutputSchema(query: String, options: JDBCOptions): StructType
}
private object MsSqlServerDialect extends JdbcDialect {
override def getQueryOutputSchema(query: String, options: JDBCOptions):
StructType = {
// The provider specific solution
}
}{code}
> Enhance JDBC Connector to use PreparedStatement.getMetaData() to resolve
> schema instead of PreparedStatement.executeQuery()
> ---
>
> Key: SPARK-40802
> URL: https://issues.apache.org/jira/browse/SPARK-40802
> Project: Spark
> Issue Type: Improvement
> Components: SQL
>Affects Versions: 2.1.0
>Reporter: Mingli Rui
>Priority: Major
> Original Estimate: 24h
> Remaining Estimate: 24h
>
> Currently, Spark JDBC Connector uses *PreparedStatement.executeQuery()* to
> resolve the JDBCRelation's schema. The schema query is like *s"SELECT * FROM
> $table_or_query WHERE 1=0".*
> But it is not necessary to execute the query. It's enough to *prepare* the
> query. With preparing the statement, the query is parsed and compiled, but is
> not executed. It will be more efficient.
> So, it's better to use PreparedStatement.getMetaData() to resolve schema.
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[jira] [Commented] (SPARK-40802) Enhance JDBC Connector to use PreparedStatement.getMetaData() to resolve schema instead of PreparedStatement.executeQuery()
[
https://issues.apache.org/jira/browse/SPARK-40802?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17619043#comment-17619043
]
Mingli Rui commented on SPARK-40802:
[~hyukjin.kwon] Thanks for the comment!
Do we know any JDBC drivers don't support this
*PreparedStatement.{{{}*getMetaData()*{}}}* ?
This interface function has been an API for *{{PreparedStatement}}* for pretty
long time. I believe it should be supported by most JDBC drivers.
Below is its definition. It does indicate {{*SQLFeatureNotSupportedException*
may be thrown. An alternative solution is that we try to use
{{getMetaData() first, if {{*SQLFeatureNotSupportedException*}}{{ is
thrown, fallback to use current implementation.}}
{code:java}
/**
* Retrieves a ResultSetMetaData object that contains
* information about the columns of the ResultSet object
* that will be returned when this PreparedStatement object
* is executed.
*
* Because a PreparedStatement object is precompiled, it is
* possible to know about the ResultSet object that it will
* return without having to execute it. Consequently, it is possible
* to invoke the method getMetaData on a
* PreparedStatement object rather than waiting to execute
* it and then invoking the ResultSet.getMetaData method
* on the ResultSet object that is returned.
*
* NOTE: Using this method may be expensive for some drivers due
* to the lack of underlying DBMS support.
*
* @return the description of a ResultSet object's columns or
* null if the driver cannot return a
* ResultSetMetaData object
* @exception SQLException if a database access error occurs or
* this method is called on a closed PreparedStatement
* @exception SQLFeatureNotSupportedException if the JDBC driver does not support
* this method
* @since 1.2
*/
ResultSetMetaData getMetaData() throws SQLException;{code}
> Enhance JDBC Connector to use PreparedStatement.getMetaData() to resolve
> schema instead of PreparedStatement.executeQuery()
> ---
>
> Key: SPARK-40802
> URL: https://issues.apache.org/jira/browse/SPARK-40802
> Project: Spark
> Issue Type: Improvement
> Components: SQL
>Affects Versions: 2.1.0
>Reporter: Mingli Rui
>Priority: Major
> Original Estimate: 24h
> Remaining Estimate: 24h
>
> Currently, Spark JDBC Connector uses *PreparedStatement.executeQuery()* to
> resolve the JDBCRelation's schema. The schema query is like *s"SELECT * FROM
> $table_or_query WHERE 1=0".*
> But it is not necessary to execute the query. It's enough to *prepare* the
> query. With preparing the statement, the query is parsed and compiled, but is
> not executed. It will be more efficient.
> So, it's better to use PreparedStatement.getMetaData() to resolve schema.
--
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[jira] [Commented] (SPARK-40802) Enhance JDBC Connector to use PreparedStatement.getMetaData() to resolve schema instead of PreparedStatement.executeQuery()
[
https://issues.apache.org/jira/browse/SPARK-40802?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17618389#comment-17618389
]
Hyukjin Kwon commented on SPARK-40802:
--
I guess the problem is that {{getMetaData}} doesn't gurantee to work in all
cases or all DBMSes. We could probably introduce a dialect to optimize this
further.
> Enhance JDBC Connector to use PreparedStatement.getMetaData() to resolve
> schema instead of PreparedStatement.executeQuery()
> ---
>
> Key: SPARK-40802
> URL: https://issues.apache.org/jira/browse/SPARK-40802
> Project: Spark
> Issue Type: Improvement
> Components: SQL
>Affects Versions: 2.1.0
>Reporter: Mingli Rui
>Priority: Major
> Original Estimate: 24h
> Remaining Estimate: 24h
>
> Currently, Spark JDBC Connector uses *PreparedStatement.executeQuery()* to
> resolve the JDBCRelation's schema. The schema query is like *s"SELECT * FROM
> $table_or_query WHERE 1=0".*
> But it is not necessary to execute the query. It's enough to *prepare* the
> query. With preparing the statement, the query is parsed and compiled, but is
> not executed. It will be more efficient.
> So, it's better to use PreparedStatement.getMetaData() to resolve schema.
--
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