本文介绍了数据库集群参数默认值的详细信息。
参数说明
PolarDB PostgreSQL版（兼容Oracle）参数默认值的设置，综合了性能、可用性以及可靠性方面的考虑，与社区版本默认值不一定相同。特别是以下参数，PolarDB根据最优性能原则进行了默认设定，您可以根据自己的需求在控制台自行修改。
| 参数 | 默认值 | 说明 |
|---|---|---|
| polar_comp_stmt_level_tx | off | 该参数用于控制异常是否回滚未提交的数据库更新。取值如下：
说明
|
| log_statement | ddl | 该参数用于设置审计日志的级别。默认为ddl，表示只有DDL对应的SQL才会进行审计，更少的日志打印可以提升数据库性能。 说明
|
常见参数默认值设置情况
| 参数 | 默认值 |
|---|---|
| authentication_timeout | 60 |
| autovacuum | on |
| autovacuum_analyze_scale_factor | 0.05 |
| autovacuum_analyze_threshold | 50 |
| autovacuum_freeze_max_age | 1200000000 |
| autovacuum_max_workers | 5 |
| autovacuum_multixact_freeze_max_age | 1400000000 |
| autovacuum_naptime | 30 |
| autovacuum_vacuum_cost_delay | 0 |
| autovacuum_vacuum_cost_limit | 10000 |
| autovacuum_vacuum_scale_factor | 0.02 |
| autovacuum_vacuum_threshold | 50 |
| backend_flush_after | 0 |
| bgwriter_delay | 10 |
| checkpoint_timeout | 30 |
| constraint_exclusion | partition |
| cpu_index_tuple_cost | 0.005 |
| cpu_operator_cost | 0.0025 |
| cpu_tuple_cost | 0.01 |
| datestyle | 'ISO,YMD' |
| deadlock_timeout | 1000 |
| default_with_oids | off |
| dynamic_shared_memory_type | posix |
| enable_partition_pruning | on |
| extra_float_digits | 0 |
| fsync | on |
| full_page_writes | off |
| gin_pending_list_limit | 4096 |
| hot_standby | on |
| hot_standby_feedback | on |
| huge_pages | on |
| idle_in_transaction_session_timeout | 3600000 |
| jit | off |
| lock_timeout | 0 |
| logging_collector | on |
| log_connections | off |
| log_disconnections | off |
| log_error_verbosity | default |
| log_min_duration_statement | 5000 |
| log_statement | ddl |
| max_files_per_process | 1000 |
| max_locks_per_transaction | 64 |
| max_prepared_transactions | 800 |
| max_replication_slots | 64 |
| max_worker_processes | 256 |
| polar_comp_stmt_level_tx | off |
| seq_page_cost | 1 |
| ssl | off |
| statement_timeout | 0 |
| synchronous_commit | on |
| temp_file_limit | 524288000 |
| timezone | 'UTC' |
| wal_buffers | 16 MB |
| wal_level | logical |
| wal_writer_delay | 10 |