feat: configure DEFAULT_SCHEMA (#532)

docs/gear_up/configuration.rst

@@ -0,0 +1,39 @@
+*************
+Configuration
+*************
+
+The SQLLineage configuration allows user to customize the behaviour of sqllineage.
+
+We adopt environment variable approach for global key-value mapping. The keys listed in this section should start with
+`"SQLLINEAGE_"` to be a valid config. For example, to use DEFAULT_SCHEMA, use ``SQLLINEAGE_DEFAULT_SCHEMA=default``.
+
+DEFAULT_SCHEMA
+==============
+Default schema, or interchangeably called database. Tables without schema qualifier parsed from SQL is set with a schema
+named `<default>`, which represents an unknown schema name. If DEFAULT_SCHEMA is set, we will use this value as
+default schema name.
+
+Default: ``""``
+
+DIRECTORY
+=========
+Frontend app SQL directory. By default the frontend app is showing the data directory packaged with sqllineage,
+which includes tpcds queries for demo purposes. User can customize with this key.
+
+Default: ``sqllineage/data``
+
+TSQL_NO_SEMICOLON
+=================
+Enable tsql no semicolon splitter mode.
+
+.. warning::
+     Transact-SQL offers this feature that even when SQL statements are not delimited by semicolon, it can still be
+     parsed and executed. But quoting `tsql_syntax_convention`_, "although the semicolon isn't required for most
+     statements in this version (v16) of SQL Server, it will be required in a future version". So this config key is
+     kept mostly for backward-compatible purposes. We may drop the support any time without warning. Bear this in mind
+     when using this feature with sqllineage.
+
+Default: ``False``
+
+
+.. _tsql_syntax_convention: https://learn.microsoft.com/en-us/sql/t-sql/language-elements/transact-sql-syntax-conventions-transact-sql?view=sql-server-ver16

docs/index.rst

@@ -31,6 +31,20 @@ First steps
     Using SQLLineage in your Python script
 
 
+Gear Up
+=======
+
+.. toctree::
+   :maxdepth: 2
+   :hidden:
+   :caption: Gear up
+
+   gear_up/configuration
+
+:doc:`gear_up/configuration`
+    Learn how to configure sqllineage
+
+
 Behind the scene
 ================
 

sqllineage/config.py

@@ -10,6 +10,8 @@ class _SQLLineageConfigLoader:
     config = {
         # for frontend directory drawer
         "DIRECTORY": (str, os.path.join(os.path.dirname(__file__), "data")),
+        # set default schema/database
+        "DEFAULT_SCHEMA": (str, ""),
         # to enable tsql no semicolon splitter mode
         "TSQL_NO_SEMICOLON": (bool, False),
     }

sqllineage/core/models.py

@@ -1,6 +1,7 @@
 import warnings
 from typing import Any, Dict, List, Optional, Set, Union
 
+from sqllineage.config import SQLLineageConfig
 from sqllineage.exceptions import SQLLineageException
 from sqllineage.utils.helpers import escape_identifier_name
 
@@ -11,8 +12,9 @@ class Schema:
     """
 
     unknown = "<default>"
+    default = SQLLineageConfig.DEFAULT_SCHEMA or unknown
 
-    def __init__(self, name: str = unknown):
+    def __init__(self, name: str = default):
         """
         :param name: schema name
         """
@@ -31,7 +33,7 @@ def __hash__(self):
         return hash(str(self))
 
     def __bool__(self):
-        return str(self) != self.unknown
+        return str(self) != self.default
 
 
 class Table: