Fix foreign key constraint errors during import

[gcsecsey]

Summary

When importing SQL dumps where tables are processed in alphabetical order (as Studio does with Jetpack backups), any table containing a FOREIGN KEY constraint referencing another table that comes later alphabetically causes the import to fail with a SQLite constraint error.

For example, a backup containing wp_cartflows_ca_email_history (which has an FK to wp_cartflows_ca_email_templates) fails because _email_history is imported before _email_templates.

This affects any WordPress plugin that uses foreign key constraints between tables.

Context

The import command already sets SET FOREIGN_KEY_CHECKS=0. However, the SQLite driver stores this as a PHP session variable, it does not translate it to SQLite’s equivalent PRAGMA foreign_keys = OFF. Both WP_SQLite_Driver and WP_SQLite_Translator enable PRAGMA foreign_keys = ON at initialization, so FK constraints remain enforced throughout the import regardless of the MySQL-level setting.

Changes

Use execute_sqlite_query() to explicitly set PRAGMA foreign_keys = OFF before the import and re-enable it afterward. After re-enabling, PRAGMA foreign_key_check validates all FK references, catching any actual data integrity issues.

Testing

I prepared this test SQL dump where a child table with an FK constraint appears before its referenced parent table:

fk-test-backup
└── sql
    ├── wp_aa_child.sql
    └── wp_zz_parent.sql

fk-test-backup.tar.gz

• Run wp sqlite import <fk-test-backup>
• Before fix: import fails with constraint error on the INSERT into the child table
• After fix: import succeeds, both tables are created with correct data