Feat/add retriever rerank (#1560)

Co-authored-by: jyong <jyong@dify.ai>

api/migrations/versions/fca025d3b60f_add_dataset_retrival_model.py

@@ -0,0 +1,43 @@
+"""add-dataset-retrival-model
+
+Revision ID: fca025d3b60f
+Revises: b3a09c049e8e
+Create Date: 2023-11-03 13:08:23.246396
+
+"""
+from alembic import op
+import sqlalchemy as sa
+from sqlalchemy.dialects import postgresql
+
+# revision identifiers, used by Alembic.
+revision = 'fca025d3b60f'
+down_revision = '8fe468ba0ca5'
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.drop_table('sessions')
+    with op.batch_alter_table('datasets', schema=None) as batch_op:
+        batch_op.add_column(sa.Column('retrieval_model', postgresql.JSONB(astext_type=sa.Text()), nullable=True))
+        batch_op.create_index('retrieval_model_idx', ['retrieval_model'], unique=False, postgresql_using='gin')
+
+    # ### end Alembic commands ###
+
+
+def downgrade():
+    # ### commands auto generated by Alembic - please adjust! ###
+    with op.batch_alter_table('datasets', schema=None) as batch_op:
+        batch_op.drop_index('retrieval_model_idx', postgresql_using='gin')
+        batch_op.drop_column('retrieval_model')
+
+    op.create_table('sessions',
+    sa.Column('id', sa.INTEGER(), autoincrement=True, nullable=False),
+    sa.Column('session_id', sa.VARCHAR(length=255), autoincrement=False, nullable=True),
+    sa.Column('data', postgresql.BYTEA(), autoincrement=False, nullable=True),
+    sa.Column('expiry', postgresql.TIMESTAMP(), autoincrement=False, nullable=True),
+    sa.PrimaryKeyConstraint('id', name='sessions_pkey'),
+    sa.UniqueConstraint('session_id', name='sessions_session_id_key')
+    )
+    # ### end Alembic commands ###