feat: Postgres max connections (#7067)

docker/.env.example

 # Whether to print SQL, default is false.
 SQLALCHEMY_ECHO=false
 
+# Maximum number of connections to the database
+# Default is 100
+#
+# Reference: https://www.postgresql.org/docs/current/runtime-config-connection.html#GUC-MAX-CONNECTIONS
+POSTGRES_MAX_CONNECTIONS=100
+
+# Sets the amount of shared memory used for postgres's shared buffers.
+# Default is 128MB
+# Recommended value: 25% of available memory
+# Reference: https://www.postgresql.org/docs/current/runtime-config-resource.html#GUC-SHARED-BUFFERS
+POSTGRES_SHARED_BUFFERS=128MB
+
+# Sets the amount of memory used by each database worker for working space.
+# Default is 4MB
+#
+# Reference: https://www.postgresql.org/docs/current/runtime-config-resource.html#GUC-WORK-MEM
+POSTGRES_WORK_MEM=4MB
+
+# Sets the amount of memory reserved for maintenance activities.
+# Default is 64MB
+#
+# Reference: https://www.postgresql.org/docs/current/runtime-config-resource.html#GUC-MAINTENANCE-WORK-MEM
+POSTGRES_MAINTENANCE_WORK_MEM=64MB
+
+# Sets the planner's assumption about the effective cache size.
+# Default is 4096MB
+#
+# Reference: https://www.postgresql.org/docs/current/runtime-config-query.html#GUC-EFFECTIVE-CACHE-SIZE
+POSTGRES_EFFECTIVE_CACHE_SIZE=4096MB
+
 # ------------------------------
 # Redis Configuration
 # This Redis configuration is used for caching and for pub/sub during conversation.

docker/docker-compose.middleware.yaml

       POSTGRES_PASSWORD: ${POSTGRES_PASSWORD:-difyai123456}
       POSTGRES_DB: ${POSTGRES_DB:-dify}
       PGDATA: ${PGDATA:-/var/lib/postgresql/data/pgdata}
+    command: >
+      postgres -c 'max_connections=${POSTGRES_MAX_CONNECTIONS:-100}'
+               -c 'shared_buffers=${POSTGRES_SHARED_BUFFERS:-128MB}'
+               -c 'work_mem=${POSTGRES_WORK_MEM:-4MB}'
+               -c 'maintenance_work_mem=${POSTGRES_MAINTENANCE_WORK_MEM:-64MB}'
+               -c 'effective_cache_size=${POSTGRES_EFFECTIVE_CACHE_SIZE:-4096MB}'
     volumes:
       - ./volumes/db/data:/var/lib/postgresql/data
     ports:

docker/docker-compose.yaml

   SQLALCHEMY_POOL_SIZE: ${SQLALCHEMY_POOL_SIZE:-30}
   SQLALCHEMY_POOL_RECYCLE: ${SQLALCHEMY_POOL_RECYCLE:-3600}
   SQLALCHEMY_ECHO: ${SQLALCHEMY_ECHO:-false}
+  POSTGRES_MAX_CONNECTIONS: ${POSTGRES_MAX_CONNECTIONS:-100}
+  POSTGRES_SHARED_BUFFERS: ${POSTGRES_SHARED_BUFFERS:-128MB}
+  POSTGRES_WORK_MEM: ${POSTGRES_WORK_MEM:-4MB}
+  POSTGRES_MAINTENANCE_WORK_MEM: ${POSTGRES_MAINTENANCE_WORK_MEM:-64MB}
+  POSTGRES_EFFECTIVE_CACHE_SIZE: ${POSTGRES_EFFECTIVE_CACHE_SIZE:-4096MB}
   REDIS_HOST: ${REDIS_HOST:-redis}
   REDIS_PORT: ${REDIS_PORT:-6379}
   REDIS_USERNAME: ${REDIS_USERNAME:-}
       POSTGRES_PASSWORD: ${POSTGRES_PASSWORD:-difyai123456}
       POSTGRES_DB: ${POSTGRES_DB:-dify}
       PGDATA: ${PGDATA:-/var/lib/postgresql/data/pgdata}
+    command: >
+      postgres -c 'max_connections=${POSTGRES_MAX_CONNECTIONS:-100}'
+               -c 'shared_buffers=${POSTGRES_SHARED_BUFFERS:-128MB}'
+               -c 'work_mem=${POSTGRES_WORK_MEM:-4MB}'
+               -c 'maintenance_work_mem=${POSTGRES_MAINTENANCE_WORK_MEM:-64MB}'
+               -c 'effective_cache_size=${POSTGRES_EFFECTIVE_CACHE_SIZE:-4096MB}'
     volumes:
       - ./volumes/db/data:/var/lib/postgresql/data
     healthcheck:

docker/middleware.env.example

 # postgres data directory
 PGDATA=/var/lib/postgresql/data/pgdata
 
+# Maximum number of connections to the database
+# Default is 100
+#
+# Reference: https://www.postgresql.org/docs/current/runtime-config-connection.html#GUC-MAX-CONNECTIONS
+POSTGRES_MAX_CONNECTIONS=100
+
+# Sets the amount of shared memory used for postgres's shared buffers.
+# Default is 128MB
+# Recommended value: 25% of available memory
+# Reference: https://www.postgresql.org/docs/current/runtime-config-resource.html#GUC-SHARED-BUFFERS
+POSTGRES_SHARED_BUFFERS=128MB
+
+# Sets the amount of memory used by each database worker for working space.
+# Default is 4MB
+#
+# Reference: https://www.postgresql.org/docs/current/runtime-config-resource.html#GUC-WORK-MEM
+POSTGRES_WORK_MEM=4MB
+
+# Sets the amount of memory reserved for maintenance activities.
+# Default is 64MB
+#
+# Reference: https://www.postgresql.org/docs/current/runtime-config-resource.html#GUC-MAINTENANCE-WORK-MEM
+POSTGRES_MAINTENANCE_WORK_MEM=64MB
+
+# Sets the planner's assumption about the effective cache size.
+# Default is 4096MB
+#
+# Reference: https://www.postgresql.org/docs/current/runtime-config-query.html#GUC-EFFECTIVE-CACHE-SIZE
+POSTGRES_EFFECTIVE_CACHE_SIZE=4096MB
 
 # ------------------------------
 # Environment Variables for sandbox Service