Hi Bob, Thanks for the email. You can select Spark as the project when you file a JIRA ticket at https://issues.apache.org/jira/browse/SPARK
For "select 1 from $table where 0=1" -- if the database's optimizer doesn't do constant folding and short-circuit execution, could the query end up scanning all the data? On Wed, Jul 15, 2015 at 11:29 AM, Bob Beauchemin <b...@sqlskills.com> wrote: > tableExists in > spark/sql/core/src/main/scala/org/apache/spark/sql/jdbc/JdbcUtils.scala > uses > non-standard SQL (specifically, the LIMIT keyword) to determine whether a > table exists in a JDBC data source. This will cause an exception in > many/most JDBC databases that doesn't support LIMIT keyword. See > > http://stackoverflow.com/questions/1528604/how-universal-is-the-limit-statement-in-sql > > To check for table existence or an exception, it could be recrafted around > "select 1 from $table where 0 = 1" which isn't the same (it returns an > empty > resultset rather than the value '1'), but would support more data sources > and also support empty tables. The standard way to check for existence > would > be to use information_schema.tables which is a SQL standard but may not > work > for other JDBC data sources that support SQL, but not the > information_schema. > > As an aside, I tried to submit a bug through JIRA, but using Create > Bug-Quick or Bug-Detailed through the Spark issue-tracker webpage appears > to > submit the bug as a bug against the Atlas project, rather than the Spark > project. > > Cheers, Bob > > > > -- > View this message in context: > http://apache-spark-developers-list.1001551.n3.nabble.com/Use-of-non-standard-LIMIT-keyword-in-JDBC-tableExists-code-tp13253.html > Sent from the Apache Spark Developers List mailing list archive at > Nabble.com. > > --------------------------------------------------------------------- > To unsubscribe, e-mail: dev-unsubscr...@spark.apache.org > For additional commands, e-mail: dev-h...@spark.apache.org > >
