Deadlock in PostgreSQL 12

[romash1408]

Flyway version: 6.1.4 (API)
DB version: PostgreSQL 12.1 on x86_64-pc-linux-gnu, compiled by gcc (GCC) 9.2.0, 64-bit

This code is calling flyway on start up:

Flyway flyway = Flyway.configure()
        .baselineOnMigrate(true)
        .dataSource(dataSource())
        .load();
flyway.migrate();

Then flyway tries to lock table, but it fails on this line

flyway/flyway-core/src/main/java/org/flywaydb/core/internal/database/postgresql/PostgreSQLAdvisoryLockTemplate.java

Line 112 in 72cfe7d

return "t".equals(rs.getString("pg_try_advisory_lock"));

because rs.getString("pg_try_advisory_lock") returns true, so we've got infinite loop

[juliahayward]

This is somewhat unexpected as the documentation claims Postgres always emits t or f - see https://www.postgresql.org/docs/current/datatype-boolean.html - however your PR makes the code better in any case. Thankyou!

[romash1408]

Potential fix #2635

[juliahayward]

Possibly related to #2506.