Problematic tests list (174 rows):
bugs.core_0203_test  CREATE VIEW ignores PLAN
bugs.core_1245_test  Incorrect column values with outer joins and views
bugs.core_1246_test  Incorrect column values with outer joins and derived tables
bugs.core_1549_test  Subquery-based predicates are not evaluated early in the join order
bugs.core_2650_test  Improve sorting performance when long VARCHARs are involved
bugs.core_2678_test  Full outer join cannot use available indices (very slow execution)
bugs.core_3076_test  Better performance for (table.field = :param OR :param = -1) in where clause
bugs.core_3450_test  Inefficient optimization (regression)
bugs.core_4165_test  Replace the hierarchical union execution with the plain one
bugs.core_4285_test  Choose the best matching index for navigation
bugs.core_4318_test  Regression: Predicates involving PSQL variables/parameters are not pushed inside the aggregation
bugs.core_4460_test  UNION sub-parts may be badly optimized. Check for ALL built-in functions.
bugs.core_4754_test  Bugcheck 167 (invalid SEND request) while working with GTT from several attachments (using EXECUTE STATEMENT ... ON EXTERNAL and different roles)
bugs.core_4880_test  Better performance of creating packages containing many functions
bugs.core_4921_test  Predicate IS [NOT] DISTINCT FROM is not pushed into unions/aggregates thus causing sub-optimal plans
bugs.core_5020_test  Regression: ORDER BY clause on compound index may disable usage of other indices
bugs.core_5070_test  Compound index cannot be used for filtering in some ORDER/GROUP BY queries
bugs.core_5236_test  IN/ANY/ALL predicates may cause sub-optimal (late filtering) execution of joins
bugs.core_5481_test  Available indices are not used in some cases if ORDER BY expression is a filtered one
bugs.core_5488_session_idle_test  Timeouts for running SQL statements and idle connections
bugs.core_5501_test  Unclear gstat's diagnostic when damaged page in DB file appears encrypted
bugs.core_5618_test  Part of the pages of the second level blobs is not released when deleting relations
bugs.core_5921_test  Provide information about Global Commit Number, Commit Number of currently used database snapshot (if any) and Commit Numbers assigned to the committed transactions
bugs.core_6095_test  Extend trace record for COMMIT/ROLLBACK RETAINING to allow chaining of transaction ids
bugs.core_6278_test  Efficient table scans for DBKEY-based range conditions
bugs.gh_0310_test  System table with keywords
bugs.gh_3218_test  Optimizer fails applying stream-local predicates before merging [CORE2832]
bugs.gh_4314_test  Sub-optimal predicate checking while selecting from a view [CORE3981]
bugs.gh_4954_test  subselect losing the index when where clause includes coalesce() [CORE4640]
bugs.gh_6785_test  Problem when restoring the database on FB 4.0 RC1 (gbak regression)
bugs.gh_6992_test  Transform OUTER joins into INNER ones if the WHERE condition violates the outer join rules
bugs.gh_7050_test  Add table MON$COMPILED_STATEMENTS and columns
bugs.gh_7137_test  Optimizer regression: bad plan (HASH instead of JOIN) is chosen for some inner joins
bugs.gh_7257_misc_datatypes_test  Support for partial indices
bugs.gh_7304_test  Events in system attachments (like garbage collector) are not traced
bugs.gh_7332_test  Remove/increase the record size limit
bugs.gh_7398_test  Worst plan sort created to execute an indexed tables
bugs.gh_7466_plans_tracking_test  Add COMPILE trace events - ability to see execution plan of every PSQL statement.
bugs.gh_7466_test  Add COMPILE trace events for procedures/functions/triggers
bugs.gh_7752_test  The access path information is truncated to 255 characters in the PLG$PROF_RECORD_SOURCES table
bugs.gh_7804_test  The partial index is not involved when filtering conditions through OR.
bugs.gh_7853_test  Do not consider non-deterministic expressions as invariants in pre-filters
bugs.gh_7904_test  More realistic cardinality adjustments for unmatchable booleans // FB5 bad plan for query
bugs.gh_7921_test  FB5 uses PK for ordered plan even if less count of fields matching index exists
bugs.gh_8061_addi_test  UNNEST subqueries invalidation. Examples when unnesting can NOT be used.
bugs.gh_8061_test  Unnest IN/ANY/EXISTS subqueries and optimize them using semi-join algorithm
bugs.gh_8077_test  Error "Too many recursion levels" does not stop execuition of code that uses ON DISCONNECT trigger (FB 4.x+)
bugs.gh_8091_test  Ability to create an inactive index
bugs.gh_8109_test  Plan/Performance regression when using special construct for IN in FB5.x compared to FB3.x
bugs.gh_8115_test  Avoid reading/hashing the inner stream(s) if the leader stream is empty
bugs.gh_8161_test  Cardinality estimation should use primary record versions only
bugs.gh_8219_test  Database creation in 3.0.12, 4.0.5 and 5.0.1 slower than in previous releases
bugs.gh_8223_test  SubQueryConversion = true: error "no current record for fetch operation" with complex joins
bugs.gh_8225_test  Problematic queries when SubQueryConversion = true
bugs.gh_8231_test  SubQueryConversion = true causes "request size limit exceeded" / "... unavailable resource. Unable to allocate memory ..."
bugs.gh_8233_test  SubQueryConversion = true - multiple rows in singleton select
bugs.gh_8250_test  Bad performance on simple two joins query on tables with composed index
bugs.gh_8252_test  Incorrect subquery unnesting with complex dependencies (SubQueryConversion = true)
bugs.gh_8265_test  Nested IN/EXISTS subqueries should not be converted into semi-joins if the outer context is a sub-query which wasn't unnested
bugs.gh_8278_test  Avoid index lookup for a NULL key if the condition is known to always be FALSE in this case
bugs.gh_8290_test  "Unique scan" is incorrectly reported in the explained plan for unique index and IS NULL predicate
bugs.gh_8434_test  Fix implicitly used collations after ALTER DOMAIN
bugs.gh_8488_test  MIN/MAX aggregates may badly affect the join order in queries with mixed INNER/LEFT joins
bugs.gh_8494_test  Fix issues with longish concatenated context aliases
bugs.gh_8618_test  Extra quotes in plan when using UNLIST function
bugs.gh_8628_test  Incorrect join order for JOIN LATERAL with UNION referencing the outer stream(s) via its select list
bugs.gh_8663_test  Problem with restore time when DB has many indices (possible regression in 6.x)
bugs.gh_8732_test  Add support of the IN <list> predicate to the equality distribution logic
bugs.gh_8749_test  Computed index on RDB$RECORD_VERSION don't work as expected
bugs.gh_8821_test  REGRESSION: natural plan instead of primary/unique index
bugs.gh_8851_test  'Internal error' when calling outer procedure after deleting unused result variable from inner procedure
bugs.gh_8902_test  FULL OUTER JOIN does not use indexes with the derived table
bugs.gh_8940_test  Better cardinality estimation for queries with many predicates (especially those not matched to any indices)
bugs.gh_8948_test  Natural scan may occur for a query that has EXISTS and several joins in the inner subquery.
functional.arno.optimizer.test_opt_aggregate_distribution_01  Try to deliver HAVING CLAUSE conjunctions to the WHERE clause
functional.arno.optimizer.test_opt_aggregate_distribution_02  Try to deliver HAVING CLAUSE conjunctions to the WHERE clause
functional.arno.optimizer.test_opt_aggregate_distribution_03  Try to deliver HAVING CLAUSE conjunctions to the WHERE clause
functional.arno.optimizer.test_opt_aggregate_distribution_04  Try to deliver HAVING CLAUSE conjunctions to the WHERE clause
functional.arno.optimizer.test_opt_aggregate_distribution_05  Try to deliver HAVING CLAUSE conjunctions to the WHERE clause
functional.arno.optimizer.test_opt_aggregate_distribution_06  Try to deliver HAVING CLAUSE conjunctions to the WHERE clause
functional.arno.optimizer.test_opt_aggregate_distribution_07  Try to deliver HAVING CLAUSE conjunctions to the WHERE clause
functional.arno.optimizer.test_opt_aggregate_distribution_08  Try to deliver HAVING CLAUSE conjunctions to the WHERE clause
functional.arno.optimizer.test_opt_aggregate_distribution_09  Try to deliver HAVING CLAUSE conjunctions to the WHERE clause
functional.arno.optimizer.test_opt_aggregate_distribution_10  Try to deliver HAVING CLAUSE conjunctions to the WHERE clause
functional.arno.optimizer.test_opt_aggregate_distribution_11  Try to deliver HAVING CLAUSE conjunctions to the WHERE clause
functional.arno.optimizer.test_opt_aggregate_distribution_12  Try to deliver HAVING CLAUSE conjunctions to the WHERE clause
functional.arno.optimizer.test_opt_aggregate_distribution_13  Try to deliver HAVING CLAUSE conjunctions to the WHERE clause
functional.arno.optimizer.test_opt_aggregate_distribution_14  Try to deliver HAVING CLAUSE conjunctions to the WHERE clause
functional.arno.optimizer.test_opt_full_join_01  FULL OUTER JOIN, list all values
functional.arno.optimizer.test_opt_full_join_02  FULL OUTER JOIN, list all values, but filtered in WHERE clause
functional.arno.optimizer.test_opt_full_join_03  FULL OUTER JOIN, list all values, but filtered in WHERE clause
functional.arno.optimizer.test_opt_full_join_04  FULL OUTER JOIN, list all values, but filtered in WHERE clause
functional.arno.optimizer.test_opt_inner_join_01  INNER JOIN join order
functional.arno.optimizer.test_opt_inner_join_02  INNER JOIN join order
functional.arno.optimizer.test_opt_inner_join_03  INNER JOIN join order
functional.arno.optimizer.test_opt_inner_join_04  INNER JOIN join order LIKE and IS NULL
functional.arno.optimizer.test_opt_inner_join_05  INNER JOIN join order LIKE and STARTING WITH
functional.arno.optimizer.test_opt_inner_join_06  INNER JOIN join order and VIEW
functional.arno.optimizer.test_opt_inner_join_07  INNER JOIN join order and VIEW
functional.arno.optimizer.test_opt_inner_join_08  INNER JOIN join order and VIEW
functional.arno.optimizer.test_opt_inner_join_09  INNER JOIN join order and distribution
functional.arno.optimizer.test_opt_inner_join_10  INNER JOIN join order
functional.arno.optimizer.test_opt_inner_join_merge_01  INNER JOIN join merge
functional.arno.optimizer.test_opt_inner_join_merge_02  INNER JOIN join merge
functional.arno.optimizer.test_opt_inner_join_merge_03  INNER JOIN join merge
functional.arno.optimizer.test_opt_inner_join_merge_04  INNER JOIN join merge and NULLs
functional.arno.optimizer.test_opt_inner_join_merge_05  INNER JOIN join merge and VIEWs
functional.arno.optimizer.test_opt_inner_join_merge_06  INNER JOIN join merge and SP
functional.arno.optimizer.test_opt_left_join_01  LEFT OUTER JOIN with no match at all
functional.arno.optimizer.test_opt_left_join_02  LEFT OUTER JOIN with no match and IS NULL in WHERE clause
functional.arno.optimizer.test_opt_left_join_04  LEFT OUTER JOIN with full match
functional.arno.optimizer.test_opt_left_join_05  LEFT OUTER JOIN with full match, but limited in ON clause
functional.arno.optimizer.test_opt_left_join_08  LEFT OUTER JOIN with full match, but limited in ON and WHERE clause
functional.arno.optimizer.test_opt_left_join_09  LEFT OUTER JOIN with full match, but limited in ON and WHERE clause
functional.arno.optimizer.test_opt_left_join_10  LEFT OUTER JOIN with IS NULL burried in WHERE clause
functional.arno.optimizer.test_opt_left_join_12  LEFT OUTER JOIN with distribution CASE
functional.arno.optimizer.test_opt_left_join_13  LEFT OUTER JOIN VIEW with full match
functional.arno.optimizer.test_opt_mixed_joins_01  Mixed JOINS
functional.arno.optimizer.test_opt_mixed_joins_02  Mixed JOINS
functional.arno.optimizer.test_opt_mixed_joins_03  Mixed JOINS
functional.arno.optimizer.test_opt_mixed_joins_04  Mixed JOINS
functional.arno.optimizer.test_opt_mixed_joins_05  Mixed JOINS
functional.arno.optimizer.test_opt_mixed_joins_06  Mixed JOINS
functional.arno.optimizer.test_opt_multi_index_selection_01  Unique index selection (multi segment)
functional.arno.optimizer.test_opt_multi_index_selection_02  Best match index selection (multi segment)
functional.arno.optimizer.test_opt_multi_index_selection_03  Best match index selection (multi segment)
functional.arno.optimizer.test_opt_multi_index_selection_04  Best match index selection (multi segment)
functional.arno.optimizer.test_opt_multi_index_selection_05  Best match index selection (multi segment)
functional.arno.optimizer.test_opt_multi_index_selection_06  Best match index selection (multi segment)
functional.arno.optimizer.test_opt_multi_index_selection_07  Best match index selection (multi segment)
functional.arno.optimizer.test_opt_multi_index_selection_08  Best match index selection (multi segment)
functional.arno.optimizer.test_opt_single_index_selection_01  Unique index selection (single segment)
functional.arno.optimizer.test_opt_single_index_selection_02  Best match index selection (single segment)
functional.arno.optimizer.test_opt_single_index_selection_03  Best match index selection (single segment)
functional.arno.optimizer.test_opt_single_index_selection_04  Best match index selection (single segment)
functional.arno.optimizer.test_opt_single_index_selection_05  Best match index selection (single segment) ASC and DESC
functional.arno.optimizer.test_opt_single_index_selection_06  Best match index selection (single segment)
functional.arno.optimizer.test_opt_single_index_selection_07  Best match index selection (single segment)
functional.arno.optimizer.test_opt_single_index_selection_08  Best match index selection (single segment)
functional.arno.optimizer.test_opt_single_index_selection_09  Best match index selection (single segment) OR
functional.arno.optimizer.test_opt_single_index_selection_10  Best match index selection (single segment) OR
functional.arno.optimizer.test_opt_single_index_selection_11  Best match index selection (single segment)
functional.arno.optimizer.test_opt_sort_by_index_01  ORDER BY ASC using index (unique)
functional.arno.optimizer.test_opt_sort_by_index_02  ORDER BY DESC using index (unique)
functional.arno.optimizer.test_opt_sort_by_index_03  ORDER BY ASC using index (non-unique)
functional.arno.optimizer.test_opt_sort_by_index_04  ORDER BY DESC using index (non-unique)
functional.arno.optimizer.test_opt_sort_by_index_05  MAX() and DESC index (non-unique)
functional.arno.optimizer.test_opt_sort_by_index_06  MAX() and ASC index (non-unique)
functional.arno.optimizer.test_opt_sort_by_index_07  MIN() and ASC index (non-unique)
functional.arno.optimizer.test_opt_sort_by_index_08  MIN() and DESC index (non-unique)
functional.arno.optimizer.test_opt_sort_by_index_09  ORDER BY ASC using index (non-unique)
functional.arno.optimizer.test_opt_sort_by_index_10  ORDER BY ASC using index (multi)
functional.arno.optimizer.test_opt_sort_by_index_11  ORDER BY ASC using index (multi)
functional.arno.optimizer.test_opt_sort_by_index_12  ORDER BY ASC, DESC using index (multi)
functional.arno.optimizer.test_opt_sort_by_index_13  ORDER BY ASC using index (multi)
functional.arno.optimizer.test_opt_sort_by_index_14  ORDER BY ASC NULLS FIRST using index
functional.arno.optimizer.test_opt_sort_by_index_15  ORDER BY ASC NULLS LAST using index
functional.arno.optimizer.test_opt_sort_by_index_16  ORDER BY DESC NULLS FIRST using index
functional.arno.optimizer.test_opt_sort_by_index_17  ORDER BY DESC NULLS LAST using index
functional.arno.optimizer.test_opt_sort_by_index_18  ORDER BY ASC using index (single) and WHERE clause
functional.arno.optimizer.test_opt_sort_by_index_19  ORDER BY ASC using index (multi) and WHERE clause
functional.dtt.test_dtt_indices_01  Index support for Declared LTT - basic test.
functional.dtt.test_dtt_max_count  DECLARED TEMPORARY TABLE - check max limit for DTT that can be created within each kind of PSQL unit.
functional.package.temp_tables_multiple_indices_test  Temporary tables in packages (#8974) - multiple indices
functional.table.alter.test_05  ALTER TABLE - ALTER - TO
functional.table.external.external_file_all_datatypes_test  External tables must accept values of all existing FB datatypes if they belong to allowed range (or set), and must reject out-of-range values
functional.tabloid.test_893488bb  (Simplified but still) cost-based choice between LOOP and HASH semi-joins
functional.tabloid.test_8f728e63  Fix cardinality estimations for semi/anti joins
functional.tabloid.test_95442bdf  Attempt to avoid hash joining for possible cardinality under-estimations
functional.tabloid.test_aae2ae32  Better fix for #8252: incorrect subquery unnesting with complex dependencies, it re-allows converting nested IN/EXISTS into multiple semi-join
functional.tabloid.test_cc183f59  Add key info to the merge join plan output
functional.tabloid.test_e260ced8  Allow computable but non-invariant lists to be used for index lookup
functional.trigger.alter.test_alter_dml_basic  ALTER TRIGGER - basic checks for DML triggers
functional.trigger.database.test_transactioncommit_01  Trigger on commit transaction. See also CORE-645

This list is the same for:
6.0.0.2177 2026.09.11 a8065634  SS