Migrate from the Same PostgreSQL Database

tip

First make sure that you have properly installed AND setup TimescaleDB within your PostgreSQL instance.

For this example we'll assume that you have a table named old_table that you want to migrate to a table named new_table. The steps are:

  1. Create a new empty table with the same table structure and other constraints as the old one, using LIKE.
  2. Convert the table to a hypertable and insert data from the old table.
  3. Add any additional indexes needed.

1. Creating the New Empty Table

There are two ways to go about this step: one more convenient, the other faster.

Convenient Method

This method recreates old_table indexes on new_table when it is created so that when we convert it to a hypertable in the next step, we don't have to make them ourselves. It avoids a step, but slows down the data transfer due to the need to update the indexes for each migrated row.

CREATE TABLE new_table (LIKE old_table INCLUDING DEFAULTS INCLUDING CONSTRAINTS INCLUDING INDEXES);

Faster Method

This method does not generate the indexes while making the table. This makes the data transfer faster than the convenient method, but requires us to add the indexes as a final step.

CREATE TABLE new_table (LIKE old_table INCLUDING DEFAULTS INCLUDING CONSTRAINTS EXCLUDING INDEXES);

2. Convert the New Table to a Hypertable

We use the TimescaleDB function create_hypertable to convert new_table to a hypertable, then simply INSERT data from the old table:

-- Assuming 'time' is the time column for the dataset
SELECT create_hypertable('new_table', 'time');

-- Insert everything from old_table
INSERT INTO new_table SELECT * FROM old_table;

warning

create_hypertable may fail if invalid UNIQUE or PRIMARY KEY indexes existed on the old table (see this note). In this case, you would have to reconfigure your indexes and/or schema.

3. Add Additional Indexes

If you used the convenient method, whatever indexes were on old_table are now on new_table making this step optional. For the faster CREATE TABLE method or for adding any indexes not on old_table, you need to add indexes to this hypertable.

CREATE INDEX on new_table (column_name, <options>)

Tada! You did it!

For more info on the best strategies for indexing, check out our schema management section.

Now check out some common hypertable commands for exploring your data.

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