Generate changelog with data error

I’m new to liquibase, and just trying to get a grasp of its capabilities.
I’ve hit an issue when trying to generate a changelog that includes data.

I’m using a postgres database, I’ve been able to generate changelogs with the default set of diffTypes, but If I try to generate the changelog including the “data” difftype I get an error.

Unexpected error running Liquibase: ERROR: current transaction is aborted, commands ignored until end of transaction block
  - Caused by: ERROR: CASE types text and "char" cannot be matched
  Position: 939

In order to eliminate anything strange with our schema/data, I tried this with a completely blank new database, and got no error but obviously no data in the output file.
I then created a single table with a single integer column - still no rows in the database.
I get the same error.

The command I’m using is:
liquibase --username=user --password=pass --url=jdbc:postgresql://localhost:5434/r2 --changelog-file new_db.xml --diffTypes="data" generate-changelog

If I increase the log level, I get the following:

[2022-11-22 10:25:50] FINE [liquibase.executor] Executing with the 'jdbc' executor
[2022-11-22 10:25:50] FINE [liquibase.diff] Cannot get object dependencies: Error executing SQL WITH RECURSIVE preference AS (
    SELECT 10 AS max_depth  -- The deeper the recursion goes, the slower it performs.
         , 16384 AS min_oid -- user objects only
         , '^(londiste|pgq|pg_toast)'::text AS schema_exclusion
         , '^pg_(conversion|language|ts_(dict|template))'::text AS class_exclusion
         , '{"SCHEMA":"00", "TABLE":"01", "CONSTRAINT":"02", "DEFAULT":"03",
      "INDEX":"05", "SEQUENCE":"06", "TRIGGER":"07", "FUNCTION":"08",
      "VIEW":"10", "MVIEW":"11", "FOREIGN":"12"}'::json AS type_ranks),
               dependency_pair AS (
                   WITH relation_object AS ( SELECT oid, oid::regclass::text AS object_name  FROM pg_class )
                   SELECT DISTINCT                          substring(pg_identify_object(classid, objid, 0)::text, E'(\\w+?)\\.') as referenced_schema_name,                          CASE classid
                              WHEN 'pg_constraint'::regclass THEN (SELECT CONTYPE FROM pg_constraint WHERE oid = objid)
                              ELSE objid::text
                              END AS CONTYPE,
                         CASE classid
                              WHEN 'pg_attrdef'::regclass THEN (SELECT attname FROM pg_attrdef d JOIN pg_attribute c ON (c.attrelid,c.attnum)=(d.adrelid,d.adnum) WHERE d.oid = objid)
                              WHEN 'pg_cast'::regclass THEN (SELECT concat(castsource::regtype::text, ' AS ', casttarget::regtype::text,' WITH ', castfunc::regprocedure::text) FROM pg_cast WHERE oid = objid)
                              WHEN 'pg_class'::regclass THEN rel.object_name
                              WHEN 'pg_constraint'::regclass THEN (SELECT conname FROM pg_constraint WHERE oid = objid)
                              WHEN 'pg_extension'::regclass THEN (SELECT extname FROM pg_extension WHERE oid = objid)
                              WHEN 'pg_namespace'::regclass THEN (SELECT nspname FROM pg_namespace WHERE oid = objid)
                              WHEN 'pg_opclass'::regclass THEN (SELECT opcname FROM pg_opclass WHERE oid = objid)
                              WHEN 'pg_operator'::regclass THEN (SELECT oprname FROM pg_operator WHERE oid = objid)
                              WHEN 'pg_opfamily'::regclass THEN (SELECT opfname FROM pg_opfamily WHERE oid = objid)
                              WHEN 'pg_proc'::regclass THEN objid::regprocedure::text
                              WHEN 'pg_rewrite'::regclass THEN (SELECT ev_class::regclass::text FROM pg_rewrite WHERE oid = objid)
                              WHEN 'pg_trigger'::regclass THEN (SELECT tgname FROM pg_trigger WHERE oid = objid)
                              WHEN 'pg_type'::regclass THEN objid::regtype::text
                              ELSE objid::text
                              END AS REFERENCED_NAME,
                          substring(pg_identify_object(refclassid, refobjid, 0)::text, E'(\\w+?)\\.') as referencing_schema_name,                           CASE refclassid
                              WHEN 'pg_namespace'::regclass THEN (SELECT nspname FROM pg_namespace WHERE oid = refobjid)
                              WHEN 'pg_class'::regclass THEN rrel.object_name
                              WHEN 'pg_opfamily'::regclass THEN (SELECT opfname FROM pg_opfamily WHERE oid = refobjid)
                              WHEN 'pg_proc'::regclass THEN refobjid::regprocedure::text
                              WHEN 'pg_type'::regclass THEN refobjid::regtype::text
                              ELSE refobjid::text
                              END AS REFERENCING_NAME
                   FROM pg_depend dep
                            LEFT JOIN relation_object rel ON rel.oid = dep.objid
                            LEFT JOIN relation_object rrel ON rrel.oid = dep.refobjid, preference
                   WHERE deptype = ANY('{n,a}')
                     AND objid >= preference.min_oid
                     AND (refobjid >= preference.min_oid OR refobjid = 2200) -- need public schema as root node
                     AND classid::regclass::text !~ preference.class_exclusion
                     AND refclassid::regclass::text !~ preference.class_exclusion
                     AND COALESCE(SUBSTRING(objid::regclass::text, E'^(\\\\w+)\\\\.'),'') !~ preference.schema_exclusion
                     AND COALESCE(SUBSTRING(refobjid::regclass::text, E'^(\\\\w+)\\\\.'),'') !~ preference.schema_exclusion
                   GROUP BY classid, objid, refclassid, refobjid, deptype, rel.object_name, rrel.object_name
 select referenced_schema_name,
      WHEN position('.' in referenced_name) >0 THEN substring(referenced_name from position('.' in referenced_name)+1 for length(referenced_name))
      ELSE referenced_name
    END)  AS referenced_name,
      WHEN position('.' in referencing_name) >0 THEN substring(referencing_name from position('.' in referencing_name)+1 for length(referencing_name))
      ELSE referencing_name
    END)  AS referencing_name from dependency_pair where REFERENCED_NAME != REFERENCING_NAME  AND ( REFERENCED_NAME like 'public.%' OR REFERENCED_NAME NOT LIKE '%.%')
 AND (CONTYPE::text != 'p' AND CONTYPE::text != 'f')
 AND referencing_schema_name is not null and referencing_name is not null: ERROR: CASE types text and "char" cannot be matched
  Position: 939

Any help would be appreciated.

Welcome to the Liquibase Community! As a user starting out, I’d recommend taking the free Liquibase University training courses to help solve issues like this. If you do it before the end of the year, you can sign up for a free certification exam, too, if you take all 4 of the main courses.