pgbench: add page (#5388)

pages/common/pgbench.md

@@ -0,0 +1,12 @@
+# pgbench
+
+> Run a benchmark test on PostgreSQL.
+> More information: <https://www.postgresql.org/docs/10/pgbench.html>.
+
+- Initialize a database with a scale factor of 50 times the default size:
+
+`pgbench --initialize --scale={{50}} {{database_name}}`
+
+- Benchmark a database with 10 clients, 2 worker threads, and 10,000 transactions per client:
+
+`pgbench --clients={{10}} --jobs={{2}} --transactions={{10000}} {{database_name}}`