Add support for setting prepare threshold in server connection. #6285

docs/en_US/server_dialog.rst

@@ -206,6 +206,12 @@ Use the fields in the *Advanced* tab to configure a connection:
   the password will not expire until your pgAdmin session does.
   Zero means the command will be executed for each new connection or reconnection that is made.
   If the generated password is not valid indefinitely, set this value to slightly before it will expire.
+* Use the *Prepare threshold* field to specify the number of times a query is
+  executed before it is prepared. If it is set to 0, every query is prepared
+  the first time it is executed. If it is set to blank, prepared statements are disabled
+  on the connection. This is particularly useful with external connection poolers,
+  such as PgBouncer, which is not compatible with prepared statements. Set this to
+  blank in such cases.
 
 .. note:: The password file option is only supported when pgAdmin is using libpq
     v10.0 or later to connect to the server.

web/migrations/versions/44b9ce549393_.py

@@ -0,0 +1,54 @@
+##########################################################################
+#
+# pgAdmin 4 - PostgreSQL Tools
+#
+# Copyright (C) 2013 - 2023, The pgAdmin Development Team
+# This software is released under the PostgreSQL Licence
+#
+##########################################################################
+
+"""Add support for prepare_threshold param
+https://www.psycopg.org/psycopg3/docs/advanced/prepare.html#prepared-statements
+
+Revision ID: 44b9ce549393
+Revises: 9426ad06a63b
+Create Date: 2023-10-12 12:15:01.757931
+
+"""
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision = '44b9ce549393'
+down_revision = '9426ad06a63b'
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    with op.batch_alter_table(
+            "server", table_kwargs={'sqlite_autoincrement': True}) as batch_op:
+        batch_op.add_column(sa.Column('prepare_threshold', sa.Integer(),
+                                      nullable=True))
+
+    with op.batch_alter_table("sharedserver") as batch_op:
+        batch_op.add_column(sa.Column('prepare_threshold', sa.Integer(),
+                                      nullable=True))
+
+    # get metadata from current connection
+    meta = sa.MetaData()
+    # define table representation
+    meta.reflect(op.get_bind(), only=('server', 'sharedserver'))
+    table = sa.Table('server', meta)
+    op.execute(
+        table.update().values(prepare_threshold=5)
+    )
+    table = sa.Table('sharedserver', meta)
+    op.execute(
+        table.update().values(prepare_threshold=5)
+    )
+
+def downgrade():
+    # pgAdmin only upgrades, downgrade not implemented.
+    pass

web/migrations/versions/9426ad06a63b_.py

@@ -35,7 +35,6 @@ def upgrade():
         batch_op.add_column(sa.Column('shared_username', sa.String(64), nullable=True))
 
 
-
 def downgrade():
     # pgAdmin only upgrades, downgrade not implemented.
     pass

web/pgadmin/browser/server_groups/servers/__init__.py

@@ -176,6 +176,7 @@ class ServerModule(sg.ServerGroupPluginModule):
         server.username = sharedserver.username
         server.server_owner = sharedserver.server_owner
         server.password = sharedserver.password
+        server.prepare_threshold = sharedserver.prepare_threshold
 
         return server
 
@@ -390,7 +391,8 @@ class ServerModule(sg.ServerGroupPluginModule):
                 tunnel_authentication=0,
                 tunnel_identity_file=None,
                 shared=True,
-                connection_params=data.connection_params
+                connection_params=data.connection_params,
+                prepare_threshold=data.prepare_threshold
             )
             db.session.add(shared_server)
             db.session.commit()
@@ -816,7 +818,8 @@ class ServerNode(PGChildNodeView):
             'shared': 'shared',
             'shared_username': 'shared_username',
             'kerberos_conn': 'kerberos_conn',
-            'connection_params': 'connection_params'
+            'connection_params': 'connection_params',
+            'prepare_threshold': 'prepare_threshold'
         }
 
         disp_lbl = {
@@ -1109,7 +1112,8 @@ class ServerNode(PGChildNodeView):
             'gss_encrypted': manager.gss_encrypted,
             'cloud_status': server.cloud_status,
             'connection_params': connection_params,
-            'connection_string': manager.display_connection_string
+            'connection_string': manager.display_connection_string,
+            'prepare_threshold': server.prepare_threshold
         }
 
         return ajax_response(response)
@@ -1202,7 +1206,8 @@ class ServerNode(PGChildNodeView):
                 passexec_cmd=data.get('passexec_cmd', None),
                 passexec_expiration=data.get('passexec_expiration', None),
                 kerberos_conn=1 if data.get('kerberos_conn', False) else 0,
-                connection_params=connection_params
+                connection_params=connection_params,
+                prepare_threshold=data.get('prepare_threshold', None)
             )
             db.session.add(server)
             db.session.commit()

web/pgadmin/browser/server_groups/servers/static/js/server.ui.js

@@ -344,9 +344,16 @@ export default class ServerSchema extends BaseUISchema {
         id: 'passexec_expiration', label: gettext('Password exec expiration (seconds)'), type: 'int',
         group: gettext('Advanced'),
         mode: ['properties', 'edit', 'create'],
-        visible: function(state) {
+        disabled: function(state) {
-          return !_.isEmpty(state.passexec_cmd);
+          return isEmptyString(state.passexec_cmd);
         },
+      },
+      {
+        id: 'prepare_threshold', label: gettext('Prepare threshold'), type: 'int',
+        group: gettext('Advanced'),
+        mode: ['properties', 'edit', 'create'],
+        helpMessageMode: ['edit', 'create'],
+        helpMessage: gettext('If it is set to 0, every query is prepared the first time it is executed. If it is set to blank, prepared statements are disabled on the connection.')
       }
     ];
   }

web/pgadmin/model/__init__.py

@@ -33,7 +33,7 @@ import config
 #
 ##########################################################################
 
-SCHEMA_VERSION = 36
+SCHEMA_VERSION = 37
 
 ##########################################################################
 #
@@ -206,6 +206,7 @@ class Server(db.Model):
     kerberos_conn = db.Column(db.Boolean(), nullable=False, default=0)
     cloud_status = db.Column(db.Integer(), nullable=False, default=0)
     connection_params = db.Column(MutableDict.as_mutable(types.JSON))
+    prepare_threshold = db.Column(db.Integer(), nullable=True)
 
 
 class ModulePreference(db.Model):
@@ -414,6 +415,7 @@ class SharedServer(db.Model):
     tunnel_password = db.Column(PgAdminDbBinaryString())
     shared = db.Column(db.Boolean(), nullable=False)
     connection_params = db.Column(MutableDict.as_mutable(types.JSON))
+    prepare_threshold = db.Column(db.Integer(), nullable=True)
 
 
 class Macros(db.Model):

web/pgadmin/utils/driver/psycopg3/connection.py

@@ -360,12 +360,15 @@ class Connection(BaseConnection):
                         return await psycopg.AsyncConnection.connect(
                             connection_string,
                             cursor_factory=AsyncDictCursor,
-                            autocommit=autocommit)
+                            autocommit=autocommit,
+                            prepare_threshold=manager.prepare_threshold
+                        )
                     pg_conn = asyncio.run(connectdbserver())
                 else:
                     pg_conn = psycopg.Connection.connect(
                         connection_string,
-                        cursor_factory=DictCursor)
+                        cursor_factory=DictCursor,
+                        prepare_threshold=manager.prepare_threshold)
 
         except psycopg.Error as e:
             manager.stop_ssh_tunnel()

web/pgadmin/utils/driver/psycopg3/server_manager.py

@@ -112,6 +112,7 @@ class ServerManager(object):
         self.gss_encrypted = False
         self.connection_params = server.connection_params
         self.create_connection_string(self.db, self.user)
+        self.prepare_threshold = server.prepare_threshold
 
         for con in self.connections:
             self.connections[con]._release()