Provide a dialect-specific Inspector instance, This method differs from direct a direct constructor call of Please use the inspect() function on an Engine or Connection in order to acquire an Inspector. The common scenario is when the reflection of a table in a schema qualifiedįashion then loads a related table that will also be performed in a schemaĭeprecated since version 1.4: The from_engine() method on Inspector is deprecated and will be removed in a future release. Table also omits its schema name and also that these two objectsĪre in the same schema, but will include it if Table is that SQLAlchemy will omit a default schema from the reflectedįoreignKe圜onstraint object if the owning The decision making it uses to assign the schema to this referenced The reflection process encounters a foreign key constraint on a tableīeing reflected, it branches out to reflect that referenced table as well. Tables were generated by the reflection process this is because when Representing these two database tables, where one or two of the additional We can find ourselves in a situation where one MetaDataĬollection may contain as many as four Table objects There is a ForeignKe圜onstraint object that is part of the Suppose “messages” has a “project_id”Ĭolumn which refers to rows in another schema-local table “projects”, meaning The above issue becomes more complicated when the tables being reflected containįoreign key references to other tables. tables is messages_table_1 True > metadata. > # reflect in non-schema qualified fashion > messages_table_1 = Table ( "messages", metadata_obj, autoload_with = someengine ) > # reflect in schema qualified fashion > messages_table_2 = Table ( "messages", metadata_obj, schema = "project", autoload_with = someengine ) > # two different objects > messages_table_1 is messages_table_2 False > # stored in two different ways > metadata. This would mean that the database accepts the following ![]() Such as PostgreSQL suppose the “project” schema is set up in the PostgreSQL Schema is the default schema of our database connection, or if using a database “project” schema in the previous example, and suppose also that the “project” ![]() To illustrate the ramifications of this issue, consider tables from the MetaData collection representing the same table in the Would be two separate Table objects in the single Qualified manner will organize it into the MetaData.tablesĬollection without being schema qualified. Conversely, reflecting the same table in a non-schema Into the MetaData.tables collection, that is, in a schema Well as an “implicit” way where no schema is present, this presents aĪ schema-qualified manner will always populate its Table.schemaĪttribute and additionally affect how this Table is organized Table object which can be referred towards both in a schema-qualified way, as Since most relational databases therefore have the concept of a particular It’s also perfectly fine if the schema name is present). Schemas will not require that the schema name be present (while at the same time Session to be “implicit” referring to a table name that it’s any of those Where multiple schema names can be considered in a particular database Take this concept further into the notion of a The reason for this is naturally that when one refers to table objects withoutĪ schema as is common, a schema-capable database will still consider that The concept of schemas usually also include the concept of a “default” schema. Similar schema parameters set to their default of None.Īs described at Specifying a Default Schema Name with MetaData, databases that have In DDL and SQL, leave corresponding Table.schema and Part of this “default” schema and can be named without schema qualification Is just a single name, and not a list of names for tables that are As a best practice, ensure the “default” schema for a database ![]() Tables that are visible in the “default schema” of a database session,Īnd how these interact with SQLAlchemy directives that include the schemaĮxplicitly. In this section, we discuss SQLAlchemy’s reflection behavior regarding
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