# Developer Options > Complete dossiers for 27 core PostgreSQL settings in Developer Options. --- Dossier URLs remain flat; this category exists only to organize browsing and the sidebar. --- Section pages: - [allow_in_place_tablespaces](/parameters/allow-in-place-tablespaces/): allow_in_place_tablespaces — Allows tablespaces directly inside pg_tblspc, for testing. Observed in PG10–19 Beta 3; its last measured boot default is off in PG19 Beta 3, with superuser context. This is a beta-snapshot fact and can change before PostgreSQL 19 GA. - [allow_system_table_mods](/parameters/allow-system-table-mods/): allow_system_table_mods — Allows modifications of the structure of system tables. Observed in PG9.0–19 Beta 3; its last measured boot default is off in PG19 Beta 3, with superuser context. This is a beta-snapshot fact and can change before PostgreSQL 19 GA. - [backtrace_functions](/parameters/backtrace-functions/): backtrace_functions — Log backtrace for errors in these functions. Observed in PG13–19 Beta 3; its last measured boot default is empty string in PG19 Beta 3, with superuser context. This is a beta-snapshot fact and can change before PostgreSQL 19 GA. - [debug_discard_caches](/parameters/debug-discard-caches/): debug_discard_caches — Aggressively flush system caches for debugging purposes. Observed in PG14–19 Beta 3; its last measured boot default is 0 in PG19 Beta 3, with superuser context. This is a beta-snapshot fact and can change before PostgreSQL 19 GA. - [debug_io_direct](/parameters/debug-io-direct/): debug_io_direct — Use direct I/O for file access. Observed in PG16–19 Beta 3; its last measured boot default is empty string in PG19 Beta 3, with postmaster context. This is a beta-snapshot fact and can change before PostgreSQL 19 GA. - [debug_logical_replication_streaming](/parameters/debug-logical-replication-streaming/): debug_logical_replication_streaming — Forces immediate streaming or serialization of changes in large transactions. Observed in PG16–19 Beta 3; its last measured boot default is buffered in PG19 Beta 3, with user context. This is a beta-snapshot fact and can change before PostgreSQL 19 GA. - [debug_parallel_query](/parameters/debug-parallel-query/): debug_parallel_query — Forces the planner's use parallel query nodes. Observed in PG16–19 Beta 3; its last measured boot default is off in PG19 Beta 3, with user context. This is a beta-snapshot fact and can change before PostgreSQL 19 GA. - [force_parallel_mode](/parameters/force-parallel-mode/): force_parallel_mode — Forces use of parallel query facilities. Observed in PG9.6–15; its last measured boot default is off in PG15, with user context. It was removed in PG16. - [ignore_checksum_failure](/parameters/ignore-checksum-failure/): ignore_checksum_failure — Continues processing after a checksum failure. Observed in PG9.3–19 Beta 3; its last measured boot default is off in PG19 Beta 3, with superuser context. This is a beta-snapshot fact and can change before PostgreSQL 19 GA. - [ignore_invalid_pages](/parameters/ignore-invalid-pages/): ignore_invalid_pages — Continues recovery after an invalid pages failure. Observed in PG13–19 Beta 3; its last measured boot default is off in PG19 Beta 3, with postmaster context. This is a beta-snapshot fact and can change before PostgreSQL 19 GA. - [ignore_system_indexes](/parameters/ignore-system-indexes/): ignore_system_indexes — Disables reading from system indexes. Observed in PG9.0–19 Beta 3; its last measured boot default is off in PG19 Beta 3, with backend context. This is a beta-snapshot fact and can change before PostgreSQL 19 GA. - [jit_debugging_support](/parameters/jit-debugging-support/): jit_debugging_support — Register JIT-compiled functions with debugger. Observed in PG11–19 Beta 3; its last measured boot default is off in PG19 Beta 3, with superuser-backend context. This is a beta-snapshot fact and can change before PostgreSQL 19 GA. - [jit_dump_bitcode](/parameters/jit-dump-bitcode/): jit_dump_bitcode — Write out LLVM bitcode to facilitate JIT debugging. Observed in PG11–19 Beta 3; its last measured boot default is off in PG19 Beta 3, with superuser context. This is a beta-snapshot fact and can change before PostgreSQL 19 GA. - [jit_expressions](/parameters/jit-expressions/): jit_expressions — Allow JIT compilation of expressions. Observed in PG11–19 Beta 3; its last measured boot default is on in PG19 Beta 3, with user context. This is a beta-snapshot fact and can change before PostgreSQL 19 GA. - [jit_profiling_support](/parameters/jit-profiling-support/): jit_profiling_support — Register JIT-compiled functions with perf profiler. Observed in PG11–19 Beta 3; its last measured boot default is off in PG19 Beta 3, with superuser-backend context. This is a beta-snapshot fact and can change before PostgreSQL 19 GA. - [jit_tuple_deforming](/parameters/jit-tuple-deforming/): jit_tuple_deforming — Allow JIT compilation of tuple deforming. Observed in PG11–19 Beta 3; its last measured boot default is on in PG19 Beta 3, with user context. This is a beta-snapshot fact and can change before PostgreSQL 19 GA. - [post_auth_delay](/parameters/post-auth-delay/): post_auth_delay — Sets the amount of time to wait after authentication on connection startup. Observed in PG9.0–19 Beta 3; its last measured boot default is 0 s in PG19 Beta 3, with backend context. This is a beta-snapshot fact and can change before PostgreSQL 19 GA. - [pre_auth_delay](/parameters/pre-auth-delay/): pre_auth_delay — Sets the amount of time to wait before authentication on connection startup. Observed in PG9.0–19 Beta 3; its last measured boot default is 0 s in PG19 Beta 3, with sighup context. This is a beta-snapshot fact and can change before PostgreSQL 19 GA. - [remove_temp_files_after_crash](/parameters/remove-temp-files-after-crash/): remove_temp_files_after_crash — Remove temporary files after backend crash. Observed in PG14–19 Beta 3; its last measured boot default is on in PG19 Beta 3, with sighup context. This is a beta-snapshot fact and can change before PostgreSQL 19 GA. - [send_abort_for_crash](/parameters/send-abort-for-crash/): send_abort_for_crash — Send SIGABRT not SIGQUIT to child processes after backend crash. Observed in PG16–19 Beta 3; its last measured boot default is off in PG19 Beta 3, with sighup context. This is a beta-snapshot fact and can change before PostgreSQL 19 GA. - [send_abort_for_kill](/parameters/send-abort-for-kill/): send_abort_for_kill — Send SIGABRT not SIGKILL to stuck child processes. Observed in PG16–19 Beta 3; its last measured boot default is off in PG19 Beta 3, with sighup context. This is a beta-snapshot fact and can change before PostgreSQL 19 GA. - [trace_connection_negotiation](/parameters/trace-connection-negotiation/): trace_connection_negotiation — Logs details of pre-authentication connection handshake. Observed in PG17–19 Beta 3; its last measured boot default is off in PG19 Beta 3, with postmaster context. This is a beta-snapshot fact and can change before PostgreSQL 19 GA. - [trace_notify](/parameters/trace-notify/): trace_notify — Generates debugging output for LISTEN and NOTIFY. Observed in PG9.0–19 Beta 3; its last measured boot default is off in PG19 Beta 3, with user context. This is a beta-snapshot fact and can change before PostgreSQL 19 GA. - [trace_recovery_messages](/parameters/trace-recovery-messages/): trace_recovery_messages — Enables logging of recovery-related debugging information. Observed in PG9.0–16; its last measured boot default is log in PG16, with sighup context. It was removed in PG17. - [trace_sort](/parameters/trace-sort/): trace_sort — Emit information about resource usage in sorting. Observed in PG9.0–19 Beta 3; its last measured boot default is off in PG19 Beta 3, with user context. This is a beta-snapshot fact and can change before PostgreSQL 19 GA. - [wal_consistency_checking](/parameters/wal-consistency-checking/): wal_consistency_checking — Sets the WAL resource managers for which WAL consistency checks are done. Observed in PG10–19 Beta 3; its last measured boot default is empty string in PG19 Beta 3, with superuser context. This is a beta-snapshot fact and can change before PostgreSQL 19 GA. - [zero_damaged_pages](/parameters/zero-damaged-pages/): zero_damaged_pages — Continues processing past damaged page headers. Observed in PG9.0–19 Beta 3; its last measured boot default is off in PG19 Beta 3, with superuser context. This is a beta-snapshot fact and can change before PostgreSQL 19 GA.