JDBC MetaData getImportedKeys query

For the DatabaseMetaData methods getImportedKeys, getExportedKeys, and
getCrossReference a large query is used that triggered the genetic query
optimizer which occasionally produced bad plans which made it look like
the driver "hung" while it executed. I've add some explicit JOIN
statements so that it no longer enables the genetic optimizer and
generates reasonable and consistent plans.

I've attached two versions of the patch. One which has an additional
change to the value of the FK_NAME column. Currently the returned value
is the triggers arguments which look like

"<unnamed>\000t2\000t1\000UNSPECIFIED\000a\000a\000"

This was required for server versions < 7.3 when a user did not supply
constraint names. Every constraint was named "<unnamed>"
. 7.3 has enforced unique constraint names per table so unnamed foreign
keys will have different names "$1", "$2" and so on. I've used logic
along the lines of the following to preserve the unique names in the
original scheme, but allow people who go to the trouble of naming their
constraints to see them:

if (triggerargs.startsWith("<unnamed>")) {
fkname = [the whole ugly trigger args name originally used];
} else {
fkname = [the actual fk name];
}

Kris Jurka