I want to Tune my PostgreSQL stored procedure which has 1000 queries Inside. My SP is suddenly started to lack Perfomance.
How can I debug this SP which query is lagging performance inside the SP? Since Explain analyze doesn’t really show the much stats on SP.
Thanks for you help out
You best use auto_explain with auto_explain.log_nested_statements, auto_explain.log_analyze and auto_explain.log_buffers turned on.
Then you get the execution plans of all SQL statements with their duration logged.
I think that if you have a single function with 1000 different SQL statements inside, your design could be improved.
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I have data that requires a daily delsupsert to 10 PostgreSQL tables, called from Python's psycopg2. My current (single) query has 30 CTEs of inserts, updates, and deletes, that get executed only at the end as far as I know.
It's clean, but it's challenging to debug and complicated to understand. What's the best way to refactor this situation for code readability and easier debugging? (Stored procedures? Raise statements?)
I am doing small research work on how to protect database against DDoS atack.
I am using postgres database in my testings.
I want to perform a DDoS of Database on my local machine. But I don't really know how to do it.
My plan is to create script that runs bunch of queries. But I want these queries took as much time to complete as possible.
I saw this example: select tab1 from (select decode(encode(convert(compress(post) using latin1),concat(post,post,post,post)),sha1(concat(post,post,post,post))) as tab1 from table_1)a;
But I am failing to replicate it in postgres.
I need help in translating this query in postgres or other examples of functions or queries that would take lots of time to complete.
Edit:
sleep functions might not work. They are not loading system enough.
In my understanding, DDoS should be performed with functions that are taking a long time to perform and sucks up tons of compute powers of the system.
I am trying to figure out if PostgreSQL query execution plans are stored somewhere (possibly as complimentary to pg_stat_statements and pg_prepared_statements) in a way they are available for longer than the duration of the session. I understand that PREPARE does cache a sql statement in pg_prepared_statements, though the plan itself does not seem to be available in any view as far as I can tell.
I am not sure if there is a doc explaining the life cycle of a query plan for PostgreSQL but from what it sounds in the EXPLAIN documentation, PostgreSQL does not cache query plans at all. Is this accurate?
Thanks!
PostgreSQL has no shared storage for execution plans, so they cannot be reused across database sessions.
There are two ways to cache an execution plan within a session:
Use prepared statements with the SQL statements PREPARE and EXECUTE. The plan will be cached for the life time of the prepared statement, usually until your session ends.
Use PL/pgSQL functions. The plans for all static SQL statements (that is, statements that are not run with EXECUTE) in such a function will be cached for the session life time.
Other than that, execution plans are not cached in PostgreSQL.
I am working on a project where i want to give people the possibility to execute SQL queries on an PostgreSQL database. I then only need to prevent people from hacking/attacking my database.
I thought that maybe a way to do that, is by giving only view access to de database connection. And using EXPLAIN ANALYSE to calculating the cost of the SQL query.
Is EXPLAIN ANALYSE trustworthy enough to make sure there are no cheap ways to get the website down?
Do you have suggestions?
EXPLAIN ANALYSE will execute the query, including any side-effects it may have. PostgreSQL also allows running arbitrary Perl and Python code if configured to do so, so be careful. You're likely better off running PostgreSQL instances in per-request VMs or in similar highly isolated environments.
I want to get to know the real time of my query execution with different hints and without it. But oracle DB caches the query after its first execution and second time it executes quickly. How can I clear this cache after each query execution?
ALTER SYSTEM FLUSH BUFFER_CACHE
More details in the manual:
http://download.oracle.com/docs/cd/B19306_01/server.102/b14200/statements_2013.htm#i2053602