Normally 8k by default.

In 8.3.0, you can change BLCKSZ in src/include/pg_config_manual.h, and recompile from source to change it.

How can you tell what the page size of your installation is? Create a table with a single item in it. Then print the size of the table - since it fits on one page, the size is the size of the page.

_[marcua@sorrel postgres]$ psql -d imdb
Welcome to psql 8.3.0, the PostgreSQL interactive terminal.

Type: \copyright for distribution terms
\h for help with SQL commands
\? for help with psql commands
\g or terminate with semicolon to execute query
\q to quit

imdb=# select 1 into test;

imdb=# select pg_size_pretty(pg_total___relation_size(‘test’));
16 kB
(1 row)

imdb=# \q