How to conditionally recreate indexes created by `CREATE INDEX ON <table_name> (<column_name>)`?

Question

I am squashing migrations and rewriting all constructs like:

CREATE TABLE entities (
  id bigint GENERATED ALWAYS AS IDENTITY PRIMARY KEY,
  title text NOT NULL,
  description text
);

CREATE INDEX ON entities (title);
CREATE INDEX ON entities (description);

Into:

CREATE TABLE IF NOT EXISTS entities (
  id bigint GENERATED ALWAYS AS IDENTITY PRIMARY KEY,
  title text NOT NULL,
  description text
);

CREATE INDEX IF NOT EXISTS ON entities (title);
CREATE INDEX IF NOT EXISTS ON entities (description);

When I run the squash I get a syntax error on the CREATE INDEX IF NOT EXISTS ON entities (title); line. After squinting harder at the docs reference I noticed IF NOT EXISTS does in fact require name after it.
So what is the right way to conditionally recreate "default" indexes like this?

Answer 1

You need to use names in CREATE INDEX statements, for example:

CREATE TABLE IF NOT EXISTS entities (
  id bigint GENERATED ALWAYS AS IDENTITY PRIMARY KEY,
  title text NOT NULL,
  description text
);

CREATE INDEX IF NOT EXISTS entities_title_idx ON entities (title);
CREATE INDEX IF NOT EXISTS entities_description_idx ON entities (description);