Creating tables and issuing queries

After this introduction to Postgres-XC and its underlying ideas, it is time to create our first table and see how the cluster will behave. The next example shows a simple table. It will be distributed using the hash key of the id column:

test=# CREATE TABLE t_test (id int4)
DISTRIBUTE BY HASH (id);
CREATE TABLE
test=# INSERT INTO t_test
SELECT * FROM generate_series(1, 1000);
INSERT 0 1000

Once the table has been created, we can add data to it. After completion, we can check whether the data has been written correctly to the cluster:

test=# SELECT count(*) FROM t_test;
count
-------
  1000
(1 row)

Not surprisingly, we have 1,000 rows in our table.

The interesting thing here is to see how the data is returned by the database engine. Let's take a look at the execution plan of our query:

test=# explain (VERBOSE TRUE, ANALYZE TRUE,
NODES true, NUM_NODES true)
SELECT count(*) FROM t_test;
QUERY PLAN
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 Aggregate...