Hello,
the use case is to iterate over MySQL shards with empty tables by
GenerateTableFetch 1.15.0.
The JDBC used is mysql-connector-java-8.0.21.jar.
The comment and exception do not seem to be correct since MySQL does return 0
rows (Empty result set fetched).
GenerateTableFetch.java:432
} else {
// Something is very wrong here, one row (even if count is
zero) should be returned
throw new SQLException("No rows returned from metadata
query: " + selectQuery);
}
TimeGenerated /SyslogMessage
1/20/2022 6:30:47 AM 30:08,079 ERROR [Timer-Driven Process Thread-7]
o.a.n.p.standard.GenerateTableFetch
GenerateTableFetch[id=77301f26-bf7b-3935-65d7-7c0bba62250b] Unable to execute
SQL select query SELECT -1 FROM vshard61.installation_shard due to
java.sql.SQLException: No rows returned from metadata query: SELECT -1 FROM
vshard61.installation_shard, routing
StandardFlowFileRecord[uuid=65a4ee24-f4ea-4f05-b700-1b2dee8501ad,claim=StandardContentClaim
[resourceClaim=StandardResourceClaim[id=1642620014051-1786413,
container=default, section=557], offset=725920,
length=585],offset=540,name=885be49a-807d-4888-8404-11413d072c40,size=9] to
failure
Test in the MySQL server with 0 rows and 'Empty result set fetched' from an
empty table.
13:09:19 SUCCESS [SELECT - 1 000 rows, 0.061 secs] Result set fetched.
Number of rows limited by Max Rows
/* contains rows */
SELECT -1 FROM vshard60.installation_shard;
13:09:19 SUCCESS [SELECT - 0 rows, 0.063 secs] Empty result set fetched
/* empty table */
SELECT -1 FROM vshard61.installation_shard;
It would be possible to detect the existence of the empty result set? Maybe too
minor issue to address?
/* returns 1 */
select if ( exists( select -1 FROM vshard60.installation_shard ), 1, 0 );
/* returns 0 */
select if ( exists( select -1 FROM vshard61.installation_shard ), 1, 0 );
