Show Tables

Show Tables

Description:
Displays all tables present in the currently selected database by reading table metadata from the in-memory catalog.

Function:

pub fn show_tables(
    catalog: &Catalog,
    db_name: &str,
)

Input:

• catalog — Read-only reference to the in-memory catalog containing database and table metadata.
• db_name — Name of the database whose tables should be displayed.

Output:

• No return value (()).
• Prints all table names in the specified database.
• Prints an appropriate message if the database does not exist or contains no tables.

Implementation:

1. Validate that the specified database exists in the catalog.
2. If the database does not exist:
   • Print an error message.
   • Return immediately.
3. Retrieve the database metadata from:

   catalog.databases

4. Check whether the database contains any tables.
5. If no tables exist:
   • Print:

     No tables found.

   • Return immediately.
6. Iterate through all table names stored in:

   database.tables

7. Print each table name to the console.
8. Log the displayed table information.

Internal API Calls:

• catalog.databases.get(db_name)

  • Retrieves the database metadata from the catalog.

• database.tables.is_empty()

  • Checks whether the selected database contains any tables.

• database.tables.keys()

  • Retrieves all table names stored in the database metadata.

• println!(...)

  • Displays table names and status messages.

• log::info!(...)

  • Records informational messages in the log.

• log::debug!(...)

  • Records debug information in the log.

Files Created/Modified:

• None.

Catalog Updates:

• None.
• The function only reads metadata from the catalog.

Notes:

• Table names are retrieved entirely from the in-memory catalog.
• No table files are opened or scanned during this operation.
• The function is read-only and does not modify database state.