DDL replication

DDL stands for data definition language, the subset of the SQL language that creates, alters, and drops database objects.

PGD provides Automatic DDL replication which makes certain DDL changes easier without your having to manually distribute the DDL change to all nodes and ensure that they’re consistent.

This section looks at how DDL replication is handled in PGD.

• PGD overview provides a general outline of what PGD’s DDL replication is capable of.

• DDL replication options looks at the options for controlling replication.

• bdr.ddl_locking examines how DDL replication uses locks to safely replicate DDL.

• Managing DDL with PGD replication give best practice advice on why and how to limit the impact of DDL changes so they do not overly affect the smooth running of the cluster.

• DDL Command handling matrix is a reference to all DDL commands, what locks they take and any special handling that may be involved in their use and execution.

• DDL role manipulation notes issues around manipulating roles over multiple databases in a cluster

• Workarounds for DDL restrictions gives a range of options for handling situations where DDL replication may present restrictions, such as altering columns, constraints and types.

• DDL-like PGD functions details the PGD functions which behave like DDL and therefore behave in a similar way and are subject to similar restrictions.

• DDL overview
  • Replicated DDL
  • Differences from PostgreSQL
  • Executing DDL on PGD systems
• DDL replication options
• DDL locking details
  • The global DDL lock
  • The global DML lock
• Managing DDL with PGD replication
  • Minimizing the impact of DDL
  • Handling DDL with down nodes
  • Statement-specific DDL replication concerns
• DDL Command handling matrix
  • Command matrix
  • Command Notes
    • ALTER SEQUENCE
    • ALTER TABLE
    • ALTER TABLE disallowed commands
    • ALTER TABLE locking
    • ALTER TABLE examples
    • ALTER TYPE
    • COMMENT ON
    • CREATE PROFILE or ALTER PROFILE
    • CREATE SEQUENCE
    • CREATE TABLE
    • CREATE TABLE AS and SELECT INTO
    • EXPLAIN
    • EXPLAIN ANALYZE Replication
    • EXPLAIN ANALYZE Locking
    • GRANT and REVOKE
    • LOCK TABLE
    • SECURITY LABEL
    • TRUNCATE Replication
    • TRUNCATE Locking
• DDL and role manipulation statements
• Workarounds for DDL restrictions
  • Adding a CONSTRAINT
  • Adding a column
  • Changing a column’s type
    • Changing other types
• PGD functions that behave like DDL