MDEV-35018 MDL BF-BF conflict on DROP TABLE #3568
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DROP TABLE on child and UPDATE of parent table can cause an MDL BF-BF conflict when applied concurrently. DROP TABLE takes MDL locks on both child and its parent table, however it only it did not add certification keys for the parent table. This patch adds the following: * Append certification keys corresponding to all parent tables before DROP TABLE replication. * Fix wsrep_append_fk_parent_table() so that it works when it is given a table list containing temporary tables. * Make sure function wsrep_append_fk_parent_table() is only called for local transaction. That was not the case for ALTER TABLE. * Add a test case that verifies that UPDATE parent depends on preceeding DROP TABLE child. * Adapt galera_ddl_fk_conflict test to work with DROP TABLE as well.
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Description
The patch fixes a case where two Galera appliers would conflict at MDL level, while
applying "DROP TABLE child" and "UPDATE parent". Where "child" has a foreign key
to table "parent". DROP TABLE takes MDL locks on both child and its parent table,
however insufficient galera certifications keys were appended, which caused these
two operation to apply concurrently.
Release Notes
Nothing.
How can this PR be tested?
The patch comes with MTR tests.
Basing the PR against the correct MariaDB version
mainbranch.PR quality check