add postgres settings

systems/palatine-hill/postgresql.nix

@@ -49,6 +49,105 @@ in
           };
         }
       ];
+      # Thank you NotAShelf
+      # https://github.com/NotAShelf/nyx/blob/d407b4d6e5ab7f60350af61a3d73a62a5e9ac660/modules/core/roles/server/system/services/databases/postgresql.nix#L74
+      # commented out statements are likely overriden by pgtune settings
+      # https://pgtune.leopard.in.ua/?dbVersion=17&osType=linux&dbType=web&cpuNum=64&totalMemory=8&totalMemoryUnit=GB&connectionNum=1024&hdType=hdd
+      settings = {
+        # Connectivity;
+        # max_connections = 100;
+        superuser_reserved_connections = 3;
+
+        # Memory Settings;
+        #shared_buffers = "1024 MB";
+        #work_mem = "32 MB";
+        #maintenance_work_mem = "320 MB";
+        #huge_pages = "off";
+        #effective_cache_size = "2 GB";
+        #effective_io_concurrency = 100; # concurrent IO only really activated if OS supports posix_fadvise function;
+        #random_page_cost = 1.25; # speed of random disk access relative to sequential access (1.0);
+
+        # Monitoring;
+        shared_preload_libraries = "pg_stat_statements,auto_explain"; # per statement resource usage stats & log explain statements for slow queries
+        track_io_timing = "on"; # measure exact block IO times;
+        track_functions = "pl"; # track execution times of pl-language procedures if any;
+        # Replication;
+        wal_level = "replica"; # consider using at least "replica";
+        max_wal_senders = 0;
+        synchronous_commit = "on";
+
+        # Checkpointing: ;
+        checkpoint_timeout = "15 min";
+        #checkpoint_completion_target = 0.9;
+        #max_wal_size = "1024 MB";
+        #min_wal_size = "512 MB";
+
+        # WAL writing;
+        wal_compression = "on";
+        wal_buffers = -1; # auto-tuned by Postgres till maximum of segment size (16MB by default);
+        wal_writer_delay = "200ms";
+        wal_writer_flush_after = "1MB";
+
+        # Background writer;
+        bgwriter_delay = "200ms";
+        bgwriter_lru_maxpages = 100;
+        bgwriter_lru_multiplier = 2.0;
+        bgwriter_flush_after = 0;
+
+        # Parallel queries: ;
+        #max_worker_processes = 6;
+        #max_parallel_workers_per_gather = 3;
+        #max_parallel_maintenance_workers = 3;
+        #max_parallel_workers = 6;
+        parallel_leader_participation = "on";
+
+        # Advanced features ;
+        enable_partitionwise_join = "on";
+        enable_partitionwise_aggregate = "on";
+        jit = "on";
+
+        jit_above_cost = 100000;
+        jit_inline_above_cost = 150000;
+        jit_optimize_above_cost = 500000;
+
+        # log slow queries
+        log_min_duration_statement = 100;
+        "auto_explain.log_min_duration" = 100;
+
+        # logging configuration
+        log_connections = true;
+        log_statement = "all";
+        logging_collector = true;
+        log_disconnections = true;
+
+        # from pgtune
+        # DB Version: 17
+        # OS Type: linux
+        # DB Type: web
+        # Total Memory (RAM): 8 GB
+        # CPUs num: 64
+        # Connections num: 1024
+        # Data Storage: hdd
+
+        max_connections = 1024;
+        shared_buffers = "2GB";
+        effective_cache_size = "6GB";
+        maintenance_work_mem = "512MB";
+        checkpoint_completion_target = 0.9;
+        #wal_buffers = "16MB"; allow auto-tuning as per above
+        default_statistics_target = 100;
+        random_page_cost = 4;
+        effective_io_concurrency = 2;
+        work_mem = "512kB";
+        huge_pages = "off";
+        min_wal_size = "1GB";
+        max_wal_size = "4GB";
+        max_worker_processes = 64;
+        max_parallel_workers_per_gather = 4;
+        max_parallel_workers = 64;
+        max_parallel_maintenance_workers = 4;
+
+      };
 
       refreshCollation = true;
       vacuumAnalyzeTimer.enable = true;