pg_stat_sql_plans ALPHA released

pg_stat_statements and auto_explain with a planid.

It is implementing many Oracle like features:

- queryid is based on normalized sql text (no jumbling),

- stored query text isn't normalized,

- a text normalization SQL function is provided,

- sql not finished in success (cancelled, timeout, errors) is tracked,

- planid is based on normalized explain plan text,

- explain plan text is saved in logs (as auto_explain do)

     but only one time per queryid/planid,

- first_call, last_call informations are kept for each entry,

- provides a SQL function retrieving queryid for a pid

     permitting to join pg_stat_activity with pg_stat_sql_plan

- includes specific wait events for planing and extension activities

Some ideas where found in other postgres extensions like pg_store_plans,

pg_stat_plans, ... and patches from pgsql-hackers mailing list.

See https://github.com/legrandlegrand/pg_stat_sql_plans

Feedbacks are welcome

Regards

PAscal