Is there a way to create a system The table was not created because the table space "TEMPTB" following the clause "IN" is a "SYSTEM TEMPORARY" table space. SQLSTATE=42838
This is the error I keep getting when I create a temp table in a temp tablespace...does db2 not support it? because oracle does.
Thanks
System Temporary tablespaces are used only for system-created temporary objects – for joins, sorts that are too large for the sort heap, table queues that overflow, etc.
You need to create a USER TEMPORARY tablespace. You can read more about the various types of tablespaces. And use the CREATE TABLESPACE command to create one.
Related
I want to create a temp table so as to be able to join it to a few tables because joining those tables with the content of the proposed temporary table takes a lot of time (fetching the content of the temporary table is time consuming.Repeating it over and over takes more and more time). I am dropping the temporary table when my needs are accomplished.
I want to know if these temporary tables would be visible over other client session(my requirement is to make them visible only for current client session). I am using postgresql. It would be great if you could suggest better alternatives to the solution I am thinking of.
PostgreSQL then is the database for you. Temporary tables done better than the standard. From the docs,
Although the syntax of CREATE TEMPORARY TABLE resembles that of the SQL standard, the effect is not the same. In the standard, temporary tables are defined just once and automatically exist (starting with empty contents) in every session that needs them. PostgreSQL instead requires each session to issue its own CREATE TEMPORARY TABLE command for each temporary table to be used. This allows different sessions to use the same temporary table name for different purposes, whereas the standard's approach constrains all instances of a given temporary table name to have the same table structure.
Pleas read the documentation.
Temporary tables are only visible in the current session and are automatically dropped when the database session ends.
If you specify ON COMMIT, the temporary table will automatically be dropped at the end of the current transaction.
If you need good table statistics on a temporary table, you have to call ANALYZE explicitly, as these statistics are not collected automatically.
By default , temporary tables are visible for current session only and temporary tables are dropped automatically after commit or closing that transaction, so you don't need to drop explicitly.
The auto vacuum daemon cannot access and therefore cannot vacuum or analyze temporary tables. For this reason, appropriate vacuum and analyze operations should be performed via session SQL commands. For example, if a temporary table is going to be used in complex queries, it is wise to run ANALYZE on the temporary table after it is populated.
Optionally, GLOBAL or LOCAL can be written before TEMPORARY or TEMP. This presently makes no difference in PostgreSQL and is deprecated
I know #temp is temp. Table valid for particular session only. but if i define #temp in two different session, and run them simultaneously will that conflict. if no then how actually these tables are stored in memory. And how is that different from ##Temp?????
Temporary tables with a single # are "local", while those with a double ## are "global".
Local ones will drop out of scope once the stored procedure that defines them is done.
Global ones can be used by other users, or by the same user from different stored procedures, or by multiple calls of the same procedure. They will get dropped only after the last user that was referencing them is no longer referencing them, i.e. after the last stored proc is complete.
All are stored in the tempdb database; none in the "memory".
From CREATE TABLE
The full name of a temporary table as stored in the sysobjects table
in tempdb is made up of the table name specified in the CREATE TABLE
statement and the system-generated numeric suffix.
So it is stored in the tempdb.
Also from Temporary Tables in SQL Server
Temporary tables and table variables are created in the TempDB
database
After dropping the table, found that the index created on the columns of the dropped table is gone. I just want to know what happens after that. Could someone please explain?
What all are the others getting dropped along with table drop?
In Oracle when dropping a table
all table indexes and domain indexes are dropped
any triggers defined on the table are dropped
if table is partitioned, any corresponding local index partitions are dropped
if the table is a base table for a view or if it is referenced in a stored procedure, function, or package, then these dependent objects are invalidated but not dropped
In Postgres
DROP TABLE always removes -
1. any indexes
2. rules
3. triggers
4. constraints
that exist for the target table.
MySQL also drops table indexes when tables are dropped.
For more info, see Does dropping a table in MySQL also drop the indexes?
By default, MS Sql Server also drops indexes when a table is dropped.
(Observed in version 13.0.4206.0.)
Does the time it takes to drop a table in SQL reflect the quantity of data within the table?
Lets say for dropping an identical table one with 100000 rows and 1000 rows.
Is this MySQL? The ext3 Linux filesystem is known to be slow to drop large tables. The time to drop will have to do more with the size of the table, more than the rows in the table.
http://www.mysqlperformanceblog.com/2009/06/16/slow-drop-table/
It will definitely depend on the dbserver and on the specific storage params in that db server and upon the existence of LOBs in the table. For MOST scenarios, it's very fast.
In Oracle, dropping a table is very quick and unlikely to matter compared to other operations you would be performing (creating the table and populating it).
It would not be idomatic to be creating and dropping tables enough in Oracle for this to be any sort of a performance factor. You would instead consider using global temporary tables.
From http://download.oracle.com/docs/cd/B28359_01/server.111/b28318/schema.htm
In addition to permanent tables,
Oracle Database can create temporary
tables to hold session-private data
that exists only for the duration of a
transaction or session.
The CREATE GLOBAL TEMPORARY TABLE
statement creates a temporary table
that can be transaction-specific or
session-specific. For
transaction-specific temporary tables,
data exists for the duration of the
transaction. For session-specific
temporary tables, data exists for the
duration of the session. Data in a
temporary table is private to the
session. Each session can only see and
modify its own data. DML locks are not
acquired on the data of the temporary
tables. The LOCK statement has no
effect on a temporary table, because
each session has its own private data.
Im reading some Oracle scripts, and I found one with this
Create Table XXY(...)
Tablespace SOME_TABLESPACE
....
NOCOMPRESS
NOPARALLEL
..
What does this mean? What is if for? There are many CreateTable statemsnts, but the Tablespace statement after is exactly the same.
As I understand SOME_TABLESPACE must exist when this script is excecuted, but thats all I could get. Is the purpose of the statement to store all the tables in the same place?
EDIT
I read this
http://www.adp-gmbh.ch/ora/concepts/tablespaces.html
"Same place" doesn't quite describe it ...
A tablespace is a grouping of common data files. With your "Create" statements you can define in which tablespace an object gets stored. Usually different types of oracle objects are stored in different tablespaces that can have different capabilities.
Some examples:
"Data" (your tables and the rows stored in these tables) are stored in a different tablespace than "system information" (such as transaction logs or "caches"). This allows you to store system information on a local drive (quick, but somewhat limited in space) and data in a Storage Area network (basically unlimited space, but not quite as fast).
Table Data and Indexes can be stored in different tablespaces which may be on different disks. Therefore, table lookup and index lookup can use different disks and be faster than if both were on the same disk.
Tablespaces and their different characteristics are oen of the many ways of tuning an Oracle DB. Lots of capabilities, lots of complexity. If all you're doing is a little development machine, there is little need to worry about it.
It creates the table in that tablespace. In the case of partitioned tables it defines that tablespace as the default for new partitions and subpartitions also.
Please read:
http://download.oracle.com/docs/cd/B10501_01/server.920/a96524/c04space.htm