When I run a script in PostgreSQL I usually do the following from psql:
my_database> \i my_script.sql
Where in my_script.sql I may have code like the following:
select a.run_uid, s.object_uid into temp_table from dt.table_run_group as a
inner join dt.table_segment as s on a.group_uid = s.object_uid;
In this particular case, I am only interested in creating temp_table with the results of the query.
Are these results in disk on the server? In memory? Is the table stored permanently?
Temporary tables are stored in RAM until the available memory is used up, at which time they spill onto disk. The relevant setting here is temp_buffers.
Either way, they live for the duration of a session and are dropped at the end automatically.
You can also drop them at the end of a transaction automatically (ON COMMIT DROP) or manually any time.
Temporary table are only visible to the the same user in the same session. Others cannot access it - and also not conflict with it.
Always use CREATE TABLE tbl AS .... The alternative form SELECT ... INTO tbl is discouraged since it conflicts with the INTO clause in plpgsql.
Your query could look like:
CREATE TEMP TABLE tbl AS
SELECT a.run_uid, s.object_uid
FROM dt.table_run_group a
JOIN dt.table_segment s ON a.group_uid = s.object_uid;
SELECT INTO table ... is the same as CREATE TABLE table AS ..., which creates a normal, permanent table.
Related
I am trying to create a temporary table with a specific name so i can use it in other queries. The problem is that when i create a temp table like this:
BEGIN
BEGIN TRANSACTION;
--delete test_temp where 1=1;
create temp table test_temp as SELECT * FROM `analytics.reports.analysis` ;
COMMIT TRANSACTION;
END;
the table name is indeed test_temp but if i will try to select * from test_temp
i get nothing. the table id always generates a new unique id.
something like analytics-prod:_script3991beb3e9868774854ac09d407f1c397428a4f6.test_temp
Is there a way to make this temp table with a pre-defined name?
What I am trying to achieve basically is create a table from a select every 15min.
I thought to create a scheduled query running this transaction that will delete + populate the temp table and then I can always reference to test_temp without changing the table id.
According to the docs:
You can refer to a temporary table by name for the duration of the current multi-statement query
So if you want to refer the table in other queries, an option could be use a permanent table in a separated dataset:
...
CREATE OR REPLACE TABLE `analytics.my_temp_dataset.test_temp` AS SELECT * FROM `analytics.reports.analysis` ;
...
In that case, you don't need a temp table but a permanent table you just replace on the next run using the CREATE OR REPLACE TABLE statement. If you are using the temp table as part of a scripting stage, then I suggest using running this instead:
BEGIN
CREATE OR REPLACE TEMP TABLE _SESSION.test_temp AS
SELECT * FROM `analytics.reports.analysis`;
-- SELECT COUNT(*) CNT FROM _SESSION.test_temp;
END;
Since it is a temp table you don't need a DROP query at the end.
You can create a temporary table in a session in BigQuery.
You can create a session via the API and then create your temporary tables in the session. The tables will then be visible to all queries using that session.
There are limitations on sessions you should be aware of:
They last up to 24 hours max
No concurrent jobs running in a session
I use temporary tables with sessions to do complex transformations in an ETL pipeline. For example:
Create session
Create temporary tables
Do joins, and other transformations, write results to temporary tables
Do final transformations and output results to permanent tables
End session
I am writing a Python API for this and will put it on github at some point. I could probably post a gist if that is helpful.
In the meantime, see Google's documentation for sessions in BigQuery:
https://cloud.google.com/bigquery/docs/sessions-intro
I already tried this:
CREATE GLOBAL TEMPORARY TABLE tempTable AS
SELECT * FROM realTable;
But then tempTable has only the structure of realTable, but not the elements themselves.
"But then tempTable has only the structure of realTable, but not the
elements themselves."
What makes a global temporary table temporary is that the data is transient. Firstly, the data is only visible within the session which inserts it; any other session will see an empty table. Secondly, the data can persist for either a transaction or the session, depending on the ON COMMIT clause; the default is ON COMMIT DELETE ROWS. Find out more.
Now the thing is, a DDL statement in Oracle issues two commits, one before and one after the statement in question. So a DDL statement is a complete, discrete transaction. Hence this ...
CREATE GLOBAL TEMPORARY TABLE tempTable AS
SELECT * FROM realTable;
... is a transaction and, as it doesn't specify the ON COMMIT clause, it will apply the default which is DELETE ROWS. So an empty table is the expected behaviour.
The solution is simple: specify the ON COMMIT statement with session-level retention:
SQL> select count(*) from t23;
COUNT(*)
----------
11
SQL> create global temporary table gtt23
2 as select * from t23
3 /
Table created.
SQL> select count(*) from gtt23;
COUNT(*)
----------
0
SQL> drop table gtt23;
Table dropped.
SQL> create global temporary table gtt23
2 on commit preserve rows
3 as select * from t23
4 /
Table created.
SQL> select count(*) from gtt23;
COUNT(*)
----------
11
SQL>
Generally, I think that a policy of CREATE GLOBAL TEMPORARY TABLE using SELECT * FROM indicates a misunderstanding of the construct. GTTs in Oracle are permanent data structures; only the records are temporary. They are not disposable objects like temporary tables in T-SQL. If that's the sort of thing you want, you should probably be using PL/SQL collections instead. Find out more.
Global temporary tables can have either transaction-level scope or session-level scope. The default is to have transaction-level scope which means that the data disappears after the transaction completes. If you do a CREATE TABLE AS SELECT to create your global temporary table, the data will be inserted but, since CREATE is DDL, the data will be removed as soon as the statement completes.
One option would be to create the structure using a query that doesn't return any data
CREATE GLOBAL TEMPORARY TABLE tempTable AS
SELECT *
FROM realTable
WHERE 1=0;
then insert the data
INSERT INTO tempTable
SELECT *
FROM realTable;
Of course, given how infrequently global temporary tables are used in Oracle (particularly in comparison to other databases), I'd want to be very certain that you really need to create a temporary table from a permanent table in the first place.
How do I lock a global temporary table in a stored procedure that's getting created and populated by a SELECT INTO statement? For example:
SELECT *
INTO ##TempEmployee
FROM Employee
This stored procedure is executed for generating reports and it's there in every client database (multi-tenant architecture using different DB per client). I do not want data in this global temporary table to be shared between clients when the report is generated concurrently. I don't have a choice but to use global temp table because I use it for generating columns on the fly using PIVOT.
Why not include it inside a transaction block like
begin transaction
SELECT *
INTO ##TempEmployee
FROM Employee
Try this,
WorkDummySQL
create table rr(id integer,name varchar(20))
insert into rr values(1,'aa')
select * from rr
Tempdb
select * into ##ta from WorkDummySQL.dbo.rr
If I create a temporary table using # sign:
SELECT * INTO #temp FROM dbo.table
Where is this table located? I can't find this from tempdb.
Those tables are created in your tempDB - but the table name might not be exactly as you defined.
In my case, I get:
#temp______________________________000000000003
Try this:
SELECT * INTO #temp FROM dbo.table
SELECT * FROM tempdb.sys.tables
You should see an entry for that temp table you've just created....
When you declare a temporary table, SQL Sever adds some additional characters on its name in order to provide a unique system name for it and then it stores it in tempDB in the sysobjects table. Even though you can query the temporary table with its logical name, internally is known with the exact name SQL Server has set.
How are you looking for them?
If you do a select you'll get the data.
But the table is only available in the session, just for the user who created it (you can have global temp tables).
They are stored in temp db.
Local temp tables can be created using hash (#) sign prior to table name.
They are visible only in current connection. When connection is dropped its scope ends as well.
It is possible to create and use local temp table with the same name simultaneously in two different connections.
Read More
http://sqlnetcode.blogspot.com/2011/11/there-is-already-object-named-temp-in.html
I suspect this issue rose from the fact that if you don't right click and refresh the 'Temporary Tables' folder, SSMS will not show you the temp table immediately.
I would like to create a temporary table in a Oracle database
something like
Declare table #table (int id)
In SQL server
And then populate it with a select statement
Is it possible?
Thanks
Yep, Oracle has temporary tables. Here is a link to an AskTom article describing them and here is the official oracle CREATE TABLE documentation.
However, in Oracle, only the data in a temporary table is temporary. The table is a regular object visible to other sessions. It is a bad practice to frequently create and drop temporary tables in Oracle.
CREATE GLOBAL TEMPORARY TABLE today_sales(order_id NUMBER)
ON COMMIT PRESERVE ROWS;
Oracle 18c added private temporary tables, which are single-session in-memory objects. See the documentation for more details. Private temporary tables can be dynamically created and dropped.
CREATE PRIVATE TEMPORARY TABLE ora$ptt_today_sales AS
SELECT * FROM orders WHERE order_date = SYSDATE;
Temporary tables can be useful but they are commonly abused in Oracle. They can often be avoided by combining multiple steps into a single SQL statement using inline views.
Just a tip.. Temporary tables in Oracle are different to SQL Server. You create it ONCE and only ONCE, not every session. The rows you insert into it are visible only to your session, and are automatically deleted (i.e., TRUNCATE, not DROP) when you end you session ( or end of the transaction, depending on which "ON COMMIT" clause you use).
CREATE GLOBAL TEMPORARY TABLE Table_name
(startdate DATE,
enddate DATE,
class CHAR(20))
ON COMMIT DELETE ROWS;
CREATE TABLE table_temp_list_objects AS
SELECT o.owner, o.object_name FROM sys.all_objects o WHERE o.object_type ='TABLE';