Can we change data directory for single table or database in postgresql.
Actually my requirement is that I want to keep all tables data in C drive but customers table data in D drive. how to achieve this?
You should create a tablespace for the tables outside the data directory.
For example:
CREATE TABLESPACE tbsp LOCATION 'D:\customer_tables';
Then add TABLESPACE tbsp to all CREATE TABLE statements that should be on D.
Related
On db2 LUW LInux: Is there a possibility to recreate tablespace somewhere aside pointing to a different tablespace name created only for the purpose of unloading data from the table. I'd like to be able to extract data or restore data from a damaged table so that you don't have to recreate the entire database, which usually takes a lot of disk space and time
You can't do it back into the original db, but you could create a separate db that contains just the tablespace with the data you're interested in:
db2 restore db foo rebuild with tablespace ( syscatspace, mytbsp )
db2 rollforward db foo to end of logs and stop
db2 export to mytable.del of del select * from mytable
How do we map the logical table to the tablespace?
Does Postgres automatically creates tablespaces when we create a table or a schema?
Tablespaces and schemas are independent from each other: the first concerns the physical placement of the table, the second the namespace.
PostgreSQL automatically creates a tablespace: it is called pg_default and is located in the base subdirectory of the data directory.
All tables you create are placed there unless:
You use the TABLESPACE clause of CREATE TABLE to place it elsewhere.
The table is in a database with a different tablespace.
You set the default_tablespace parameter to a different tablespace.
Tablespaces are rarely needed, and usually it is best to keep all tables in the default tablespace.
Using DB2 v9.7 (windows), with an SMS tablespace.
Inside the tablespace folder are files for the various db objects.
Ex) SQL00003.IN1, SQL00003.DAT, etc..
How do I determine which database object corresponds to which file?
(for both indexes and tables)
The digits in the file name (i.e. 00003 = 3) correspond to the TABLEID column from SYSCAT.TABLES. Please note that TABLEID is unique only within a single tablespace, so you need to know what tablespace's container path you are looking at to make this correlation.
All table data is stored in the .DAT file.
All index data (for all indexes) is stored in the .INX file, regardless of how many indexes there are. (Note that it appears you have a typo in the filename SQL00003.IN1 above, this should be SQL00003.INX)
If your table has LOBs, then there will be 2 additional files with the same SQLxxxxx name: a .LBA and a .LB file.
For one of my issue, I am trying to understand the functionalities of below DB2 entities,
System Temporary table space.
Page Size.
Table Space.
Buffer Pool.
And below is my observation,
There is a TableSpace linked to a table in the DB2 table syscat.tables
The TableSpaces are linked to BufferPool with the relation defined in syscat.tablespaces
System Temporary table space is the table space that the DB might use while executing the query.
Page Size is an unit that defines the limit of a TableSpace and says how much data can a TableSpace can hold.
Is there something wrong in my above understandings? And when I excute a query how does the DB chooses which TableSpace to choose?
I am creating a table with tablespace:
CREATE TABLE SALARY.....
IN ACCOUNTING INDEX IN ACCOUNT_IDX
Where will the Accounting and Account_IDX be created?
The script that you have above will create SALARY in the ACCOUNTING tablespace, with indexes for that table in ACCOUNT_IDX tablespace.
The ACCOUNTING and ACCOUNT_IDX tablespaces need to be created in a separate script that has CREATE TABLESPACE statements.
If you look at the syntax for CREATE TABLESPACE, the USING part of the statement will tell DB2 where to put the files for the tablespace.
DB2 Create Tablespace Reference