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https://issues.apache.org/jira/browse/FLINK-19435?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17245898#comment-17245898
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Kezhu Wang commented on FLINK-19435:
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[~lzljs3620320] From capability side, it is nice to have driver class
customization. But current implementation has margin to support this:
1. {{driverName}} is not used to filter {{Driver}} now.
2. {{PostgresCatalog}} and {{JdbcCatalog}} does not take {{driverName}} into
account.
3. {{PostgresDialect.getRowConverter}} is tied to {{org.postgresql:postgresql}}.
4. Which driver should be default for jdbc dialect/connection if no
{{driverName}} specified ? I prefer to driver selected by
{{DriverManager.getConnection}}, it make {{JdbcDialect}} a step to
driver-agnostic and free clients from caring about concrete driver class. But
we may meet api compatibility issue as {{JdbcConnectionOptions}} has its own
exposing path besides sql.
[~lzljs3620320] [~jark] I think we may need steps to solve all discussions in
this jira:
1. Fix deadlock issue by ensuring {{DriverManager}} is loaded before
{{Class.forName(driverName)}}. We need touch {{JdbcInputFormat}},
{{JdbcLookupFunction}}, {{JdbcRowDataLookupFunction}} and
{{SimpleJdbcConnectionProvider}}.
2. Migrate {{JdbcInputFormat}}, {{JdbcLookupFunction}},
{{JdbcRowDataLookupFunction}} to {{SimpleJdbcConnectionProvider}}.
3. Support driver class filter in {{SimpleJdbcConnectionProvider}}. We could
assert this support in test with fake driver classes.
4. Solve rest concerns, such as: should {{JdbcConnectionOptions.driverName}} be
optional from {{JdbcSink}} and sql ?
What do you think ?
> jdbc JDBCOutputFormat open function invoke Class.forName(drivername)
> --------------------------------------------------------------------
>
> Key: FLINK-19435
> URL: https://issues.apache.org/jira/browse/FLINK-19435
> Project: Flink
> Issue Type: Improvement
> Components: Connectors / JDBC
> Affects Versions: 1.10.2
> Reporter: xiaodao
> Priority: Major
> Fix For: 1.13.0, 1.12.1
>
> Attachments: image-2020-10-09-20-48-48-261.png,
> image-2020-10-09-20-49-23-644.png
>
>
> when we sink data to multi jdbc outputformat ,
> {code}
> protected void establishConnection() throws SQLException,
> ClassNotFoundException {
> Class.forName(drivername);
> if (username == null) {
> connection = DriverManager.getConnection(dbURL);
> } else {
> connection = DriverManager.getConnection(dbURL, username, password);
> }
> }
> {code}
> may cause jdbc driver deadlock. it need to change to synchronized function.
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