Schema reader

Reads the schema of database objects - tables, views, procedures and functions - and emits it as descriptors: columns with types, keys and foreign keys for tables and views, parameters for routines. Its main use is the branch of an AI tool, so the model can look up tables before it writes SQL; it also serves to document a database or drive generic flows.

Pins

Pin	Kind	Types	Description
Input	input	any	Triggers the read.
Output	output	Viaducta.Plugins.DatabaseSchema.Types.DatabaseObjectDescriptor or Viaducta.Plugins.DatabaseSchema.Types.DatabaseSchemaContainer	One descriptor per object, or one container with all of them when OutputCollection is true.

Configuration

Field	Type	Default	Description
ConnectionString	database link name		Required. Name of a repository database link (link selector). Looked up by exact name; a raw connection string or #name prefix is not resolved.
SearchTerm	string		Object filter, written object or schema.object; * is a wildcard and the object part matches anywhere in the name (sales.cust finds sales.customers and sales.old_customers). Without a schema all schemas are searched. Empty = all objects.
IncludeTables	boolean	true	Include tables.
IncludeViews	boolean	true	Include views.
IncludeProcedures	boolean	true	Include stored procedures.
IncludeFunctions	boolean	true	Include functions.
OutputCollection	boolean	false	true emits one DatabaseSchemaContainer; false emits one DatabaseObjectDescriptor per object. Triggers reconfigure.
MaxItemsToReturn	integer 1-1000	20	Maximum objects per category (4 categories = up to 4x this number).
CacheSeconds	integer	300	How long a read schema is reused for the same settings and search term. 0 reads the database on every input.

Behaviour

• Reconfigure (changing OutputCollection) sets the Output type to the container or the single descriptor.
• Per input the selected categories are listed (up to MaxItemsToReturn each) and each object is described. The database connection is released before anything is emitted.
• DatabaseObjectDescriptor: Name (schema.object, quoted as the database needs it, e.g. sales."orders" on PostgreSQL), ShortName and NameSpace (schema) unquoted, Kind (Table, View, Procedure, Function), and
  • tables and views: Columns with Name, DbType, IsNullable, Ordinal, IsPrimaryKey, IsGeneratedValue (identity or computed) and ForeignKey (ReferencedSchema, ReferencedTable, ReferencedColumn);
  • procedures and functions: Inputs and Outputs with Name, DbType, IsNullable, Ordinal.
• In JSON, fields that do not apply are left out: Columns for routines, Inputs/Outputs for tables, IsPrimaryKey/IsGeneratedValue when false, ForeignKey when there is none.
• DatabaseSchemaContainer: DatabaseName, the four Include... flags, HasMore and DatabaseObjects. HasMore is true when a category had more objects than MaxItemsToReturn; narrow SearchTerm to see the rest.
• An object that cannot be described (unsupported column type, dropped meanwhile, no permission) is skipped with a warning in the log; the others are still emitted. Overloaded routines appear once.
• With CacheSeconds above 0, the result is kept per component and per combination of link, search term, categories and limit. Changes to the database show up after the time runs out.

Notes

• There is no Continue pin; connect follow-up logic to Output (with OutputCollection = true it is called exactly once per input).
• In an AI tool branch use OutputCollection = true, so the tool returns one result, and bind SearchTerm to a tool argument so the model can search.
• Foreign keys are read for SQL Server and DB2 only; other databases return columns without ForeignKey. Description is not filled in yet.
• Overloaded routines: PostgreSQL returns one of the overloads; Db2 and Snowflake skip them with a warning. Oracle packaged routines appear as schema.package.routine.
• Which objects come back when the limit cuts a list is decided by the database, not by name. Describing an object takes several metadata queries; keep MaxItemsToReturn small on large databases and leave the cache on.

Example

{ "ConnectionString": "MainDb", "SearchTerm": "{input.TableName}", "IncludeTables": true, "IncludeViews": true, "IncludeProcedures": false, "IncludeFunctions": false, "OutputCollection": true, "MaxItemsToReturn": 20, "CacheSeconds": 300 }

AI tool (Output, type with a TableName string) → Schema reader → AI tool (Input, type Viaducta.Plugins.DatabaseSchema.Types.DatabaseSchemaContainer)