There's a number of queries issued by the Hibernate test suite that we don't execute properly or cannot parse (for various different reasons), this issue tracks them as they're found and fixed. This list is incomplete and growing as we find more:

Most important:

• information_schema._pg_expandarray - sql: support Hibernate's use of _pg_expandarray #16971

Mildly more important:

• time datatype - sql: time datatype #16490
• CREATE TEMPORARY TABLE ... - sql: Add support for TEMP tables #5807
• Hibernate tries to load SERIAL types into an int, which fails if they are too large - testDirectIdPropertyAccess -sql: Hibernate tries to load SERIAL types into an int #22607
  • sql: 32 bit SERIAL type sql: 32 bit SERIAL type #24062
• int/float operations (like 1::int + float::int) - testQuotientConversion -sql: Hibernate's use of int/float operations #24063
• Adding a foreign key without having an index
  • This often doesn't actually result in the tests failing
• sql: Support ALTER TABLE __ ADD CONSTRAINT __ FOREIGN KEY __ statements sql: Support ALTER TABLE __ ADD CONSTRAINT __ FOREIGN KEY __ statements #8855

Mildly less important:

• ALL operator with subqueries (rather than just arrays) - testEqualAll - sql: ANY/ALL with subqueries #17662
• Sequences - Auto Increment function #16445
  • We can disable sequences in a dialect
• Correlated subqueries - testCollectionIsEmptyCriteria
• Types besides int8 - testConstructorResultNativeQuery - sql: support Postgres syntax names for all types #14493
  • We can remap the names to int in a dialect, but just doing this seems to break Hibernate's type inference.
• current_time - testDateTimeFunctions - sql: timetz datatype #20944
• SELECT ... FOR UPDATE - can be worked around via a dialect - sql: explicit lock syntax (SELECT FOR {SHARE,UPDATE} {skip locked,nowait}) #6583
• sql: Implement "ESCAPE" sql: Implement "ESCAPE" #23538

Other:

• sql: statement with parameters much slower than with string concatenation sql: statement with parameters much slower than with string concatenation #21463
• Run the Hibernate test suite and capture examples of failed queries Run the Hibernate test suite and capture examples of failed queries  #24741
• sql: use Hibernate's test suite sql: use Hibernate's test suite #15821

Some of them would probably be better to fix in CockroachDB itself (like temporary tables) and some would be better fixed by a custom Hibernate dialect, and some might be infeasible to fix at all at present.