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Dependencies: >= Python 3.2, Mako, pycparserIf you only have a Python you can use the virtual environment:

virtualenv envsource ./env/bin/activatepip install -r ./requirements.txt

Then you need to generate C code and compiled it:

make USE_PGXS=1 genparsermake USE_PGXS=1make USE_PGXS=1 install

and modify your postgres config:

shared_preload_libraries = 'sr_plan.so'

In your db:

CREATE EXTENSION sr_plan;

If you want to save the query plan is necessary to set the variable:

setsr_plan.write_mode= true;

Now plans for all subsequent requests will be stored in the table sr_plans. It must be remembered that all requests will be maintained including duplicates.Making an example query:

select query_hashfrom sr_planswhere query_hash=10;

disable saving the query:

setsr_plan.write_mode= false;

Now verify that your query is saved:

select query_hash, enable, valid, query, explain_jsonb_plan(plan)from sr_plans;

explain_jsonb_plan function allows you to display explain execute the plan of which lies in jsonb. By default, all the plans are off, you need enable it:

update sr_plansset enable=truewhere query_hash=812619660;

(812619660 for example only)After that, the plan for the query will be taken from the sr_plans.

In addition sr plan allows you to save a parameterized query plan. In this case, we have some constants in the query are not essential.For the parameters we use a special function _p (anyelement) example:

select query_hashfrom sr_planswhere query_hash=1000+_p(10);

if we keep the plan for the query and enable it to be used also for the following queries:

select query_hashfrom sr_planswhere query_hash=1000+_p(11);select query_hashfrom sr_planswhere query_hash=1000+_p(-5);