This problem scenario may sounds strange but I am trying to write a trigger to log the query type into another table and so far i havent been able to find anything on google
the database i am using is postgres
i.e.
if i have two tables; table1 and querylog(has a string field called querytype)
and a select query is executed on table1, i want to insert a row into the query log table with the querytype field populated with "select"
anyone have any idea how to reference the query type in a function that will be called by a trigger?
Triggers do not get called for SELECT queries, so that won't work.
If you want to audit queries, you can use the PostgreSQL log file or tools like pgaudit that hook into PostgreSQL to retrieve and log the information.
Related
I would like to change schema of few tables in my Postgres DB. Problem is that all the time there are long running queries and as I understand schema change needs exclusive lock.
Question is how can I do it? Of course I can kill all existing queries and try to do schema rename (move table to different schema) but there is a huge chance that in the meantime new queries will appear.
Thanks for help!
run SELECT pg_backend_pid() before running the ALTER TABLE
start the ALTER TABLE statement
in a second database session, run SELECT pg_blocking_pids(12345), where 12345 is the result from the first query
cancel all the blocking transactions found with the previous query with SELECT pg_cancel_backend(23456)
I have created the following materialized query table:
CREATE TABLE SCHEMA.TABLE AS
(SELECT * FROM SCHEMA.TABLEEXAMPLE)
DATA INITIALLY DEFERRED
REFRESH DEFERRED
MAINTAINED BY USER
DISABLE QUERY OPTIMIZATION;
When I execute a REFRESH TABLE SCHEMA.TABLE it get locked for others users to read from it.
Reading this doc from IBM https://www.ibm.com/support/knowledgecenter/en/SSEPGG_9.7.0/com.ibm.db2.luw.sql.ref.doc/doc/r0000977.html
I tried to execute this statement:
REFRESH TABLE SCHEMA.TABLE ALLOW READ ACCESS
But I get the following error: SQL State: 42601 Unexpected keyword ALLOW
What I'm missing on statement? Is there other way to allow read access to materialized query table while it is beign updated?
MQTs on Db2 for IBM i lag behind the functionality available in Db2 for LUW.
I've never bother with them, instead an encoded vector index (EVI) with computed columns meets every need I've every considered. (Note that Db2 LUW doesn't have EVIs)
Per Mao's comment, you might try deleting an recreating the MQT with the following:
CREATE TABLE SCHEMA.TABLE AS
(SELECT * FROM SCHEMA.TABLEEXAMPLE)
DATA INITIALLY DEFERRED
REFRESH DEFERRED
MAINTAINED BY USER
DISABLE QUERY OPTIMIZATION
with NC;
But I think a refresh would still require exclusive access to the MQT.
The only options I can think of for "refreshing" an MQT while it is being used
programmatically , using either triggers on the base tables or perhaps a process that uses SQL to update a few rows at a time.
removing the DISABLE QUERY OPTIMIZATION and not accessing the MQT directly. Instead depend on the optimizer to access it when appropriate. Now you can create a version of it every few hours and the Db should start using the newer version for new queries. Once the older one is no longer being used, you delete it (or REFRESH it)
Need a SELECT query that can find the users,procpids along with query statements runs by them with the waiting_state when a particular table is accessed in their respective queries which as a result leads to the concept of blocking table and waiting table.
Thanks.
I have two schemas in my Postgres BOOK database, MSPRESS and ORELLY.
I want to create the same table in two schemas:
CREATE TABLE MSPRRESS.BOOK(title TEXT, author TEXT);
CREATE TABLE ORELLY.BOOK(title TEXT, author TEXT);
Now, I want to create the same table in all my schemas with a single command.
To accomplish this, I thought about event triggers available in Postgres 9.3 (http://www.postgresql.org/docs/9.3/static/event-triggers.html). Intercepting CREATE TABLE command by my event trigger, I thought to determine name of table and schema in which it is created and just repeat the same command for all available schemas. Sadly, event trigger procedure does not get name of table being created.
Is there a way to 'real-time' synchronization of Postgres schema?
Currently only TG_EVENT and TG_TAG is available from an event trigger, but this feature will likely be expanded. In the meantime, you can query information_schema for differences and try to add every table, where its missing; but don't forget that this synchronization will also trigger several event triggers, so you should do it carefully.
But if you just want to build several schemas with the same structure (without further synchronization), you could just write schema-less queries to build them & run it on every schema one-by-one, after changing search path with SET search_path / SET SCHEMA.
I am using Orable DB in my application and SQL Developer Query Browser for UI Purpose.
Today I faced a very strage issue, I run a query in the query browser which gives me records successfully. But under the connection -> Table tree hierarchy, no tables are displayed.
From stackoverflow I got a solution from here : SQLDeveloper displays no tables under connections where it says tables
But under "Other Users" tree, it displays large list of schemas. So I am confused which schema is used by me query.
Any suggestion ??
Assuming that you are running a query that involves an unqualified identifier
SELECT *
FROM some_object
and that you haven't done something odd like changing the current_schema of the session, the object is either something that exists in your schema or is a public synonym.
SELECT owner, object_type, object_name
FROM all_objects
WHERE object_name = 'SOME_OBJECT'
will show you all the objects that you have access to with that name.