PostgreSQL: Can you create an index in the CREATE TABLE definition?

Question

I want to add indexes to some of the columns in a table on creation. Is there are way to add them to the CREATE TABLE definition or do I have to add them afterward with anot

Answer 1

There doesn't seem to be any way of specifying an index in the CREATE TABLE syntax. PostgreSQL does however create an index for unique constraints and primary keys by default, as described in this note:

PostgreSQL automatically creates an index for each unique constraint and primary key constraint to enforce uniqueness.

Other than that, if you want a non-unique index, you will need to create it yourself in a separate CREATE INDEX query.

Answer 2

Peter Krauss is looking for a canonical answer:

There are a MODERN SYNTAX (year 2020), so please explain and show examples, compatible with postgresql.org/docs/current/sql-createtable.html

You are searching for inline index definition, which is not available for PostgreSQL up to current version 12. Except UNIQUE/PRIMARY KEY constraint, that creates underlying index for you.

CREATE TABLE

[ CONSTRAINT constraint_name ] { CHECK ( expression ) [ NO INHERIT ] | UNIQUE ( column_name [, ... ] ) index_parameters | PRIMARY KEY ( column_name [, ... ] ) index_parameters |

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The sample syntax of inline column definition(here SQL Server):

CREATE TABLE tab(
  id INT PRIMARY KEY,                            -- constraint
  c INT INDEX filtered (c) WHERE c > 10,         -- filtered index
  b VARCHAR(10) NOT NULL INDEX idx_tab_b,        -- index on column
  d VARCHAR(20) NOT NULL,
  INDEX my_index NONCLUSTERED(d)                 -- index on column as separate entry
);

db<>fiddle demo

The rationale behind introducing them is quite interesting What are Inline Indexes? by Phil Factor

Answer 3

No.

However, you can create unique indexes in the create, but that's because they are classed as constraints. You can't create a "general" index.