Parameters
Client Connection Defaults
46 PostgreSQL 18.6 parameters. Each one has its own animation and explanation.
Locale and Formatting
DateStyle: How dates are printed (ISO, SQL, Postgres, German) and how 03/07 is read (MDY/DMY).IntervalStyle: How interval values are printed: postgres, postgres_verbose, sql_standard or iso_8601.TimeZone: Time zone used to show timestamptz values and to read timestamps without a zone.client_encoding: Character set the client speaks; the server converts text to and from it.default_text_search_config: Text search configuration used by to_tsvector/to_tsquery when none is named.extra_float_digits: Digits printed for float values: 1 or more gives exact round-trip output.icu_validation_level: Message level used when an ICU locale string looks invalid (since PG 16).lc_messages: Language of error and log messages (if translations are installed).lc_monetary: Locale for currency formatting: the money type and to_char L (symbol).lc_numeric: Locale for number formatting in to_char (G group and D decimal separators).lc_time: Locale for day and month names in to_char (TM prefix).timezone_abbreviations: Which set of abbreviations (EST, IST…) is accepted when reading timestamps.
Other Defaults
dynamic_library_path: Directories searched for a shared library named without a path.extension_control_path: Directories searched for extension .control files (new in PostgreSQL 18).gin_fuzzy_search_limit: Soft cap on rows a GIN index scan returns; extra matches are randomly dropped.
Shared Library Preloading
jit_provider: Which library compiles queries to machine code when JIT kicks in (llvmjit).local_preload_libraries: Libraries any user may have loaded at connection start (only from $libdir/plugins).session_preload_libraries: Libraries loaded at the start of every new session (superuser-set, no restart).shared_preload_libraries: Libraries loaded once at server start; required for shared memory or workers.
Statement Behavior
bytea_output: Text format for binary (bytea) values: hex (default) or the old escape format.check_function_bodies: Validate function bodies at CREATE FUNCTION time (pg_dump turns it off).client_min_messages: Lowest message level sent to the client (NOTICE by default). Errors always go.createrole_self_grant: Auto-grant roles you create to yourself (set / inherit) when you have CREATEROLE.default_table_access_method: Storage engine for new tables when CREATE TABLE has no USING clause (heap).default_tablespace: Tablespace for new tables and indexes when none is given (empty = database default).default_toast_compression: Compression for large column values when the column does not specify one: pglz or lz4.default_transaction_deferrable: Start serializable read-only transactions as DEFERRABLE (wait, then run without risk).default_transaction_isolation: Isolation level of every new transaction (read committed by default).default_transaction_read_only: Make every new transaction read-only unless it asks otherwise.event_triggers: Master switch for event triggers; turn off to repair a broken one (since PG 17).gin_pending_list_limit: Size at which a GIN index fastupdate pending list is merged into the main index.idle_in_transaction_session_timeout: Kill sessions that sit idle inside an open transaction for too long.idle_session_timeout: Disconnect sessions that are idle (outside any transaction) for too long.lock_timeout: Give up waiting for a lock after this long (per lock attempt).restrict_nonsystem_relation_kind: Refuse to access user-defined views and/or foreign tables (used by pg_dump).row_security: If off, queries that would be filtered by row-level security policies fail instead.search_path: Schemas searched, in order, for table/function names written without a schema.session_replication_role: Trigger/rule firing mode: origin (normal), replica (skips normal triggers and FKs), local.statement_timeout: Cancel any statement that runs longer than this (0 = no limit).temp_tablespaces: Tablespaces for temporary tables and sort/hash spill files (empty = database default).transaction_deferrable: Current transaction is DEFERRABLE (only matters for serializable read-only).transaction_isolation: Isolation level of the current transaction; set it before the first query.transaction_read_only: Read-only status of the current transaction.transaction_timeout: Terminate a session whose transaction lasts longer than this (new in PG 17).xmlbinary: How binary values are encoded inside XML: base64 or hex.xmloption: Whether text cast to xml must be a full DOCUMENT or may be a CONTENT fragment.