There is no limit on the number of rows in a table but it is limited to available disk space and memory/swap space. If you are storing rows that exceed 2 KB aggregated data size, then the maximum number of rows may be limited to 4 billion or less.
Counting is one of the easiest SQL statements, so it is also many people's first experience of a PostgreSQL query.
From any interface, the SQL command used to count rows is as follows:
SELECT count(*) FROM table;This will return a single integer value as the result.
In psql, the command looks like the following:
postgres=# select count(*) from orders; count ------- 345 (1 row)
PostgreSQL can choose between two techniques available to compute the SQL count(*) function. Both are available in all the currently supported versions: