I tried getting the number of tables of a particular tablespace and database from SYSIBM.SYSTABLES using the select query. This number is more than the number of tables for the same tablespace and database stored in the SYSIBM.SYSTABLESPACE table under the NTABLES column. Why is this so?
It could be the fact that systables stores entries for each table, view or alias, in fact a large number of objects that may not necessarily be included within a tablespace.
You could confirm this by only listing those where type = 'T' (or some other combination of the allowed values).
If you select count(*) from systables (for a given tablespace) and group it by type, you may find it reasonably easy to assign some of those types to the tablespace.
Related
postrgresql noob, PG 9.4.x, no access to application code, developers, anyone knowledgeable about it
User database CT has 427GB pg_largeobject (PGLOB) table, next largest table is 500ish MB.
Per this post (Does Postgresql use PGLOB internally?) a very reputable member said postgresql does not use PGLOB internally.
I have reviewed the schema of all user tables in the database, and none of them are of type OID (or lo) - which is the value used for PGLOB rows to tie the collection of blob chunks back to a referencing table row. I think this means I cannot use vacuumlo (vacuumlo) to delete orphaned PGLOB rows because that utility searches user objects for those two data types in user tables.
I HAVE identified a table with an integer field type that has int values that match LOID values in PGLOB. This seems to indicate that the developers somehow got their blobs into PGLOB using the integer value stored in a user table row.
QUESTION: Is that last statement possible?
A) If it is not, what could be adding all this data to PGLOB table?
B) If it is possible, is there a way I can programatically search ALL tables for integer values that might represent rows in PGLOB?
NEED: I DESPERATELY need to reduce the size of the PGLOB table, as we are running out of disk space. And no, we cannot add space to existing disk per admin. So I somehow need to determine if there are LOID values in PGLOB that do NOT exist in ANY user tables as integer-type fields and then run lo_unlink to remove the rows. This could get me more usable 8K pages in the table.
BTW, I have also run pg_freespace on PGLOB, and it identified that most of the pages in PGLOB did not contain enough space in which to insert another blob chunk.
THANKS FOR THE ASSISTANCE!
Not really an answer but thinking out loud:
As you found all large objects are stored in a single table. The oid field you refer to is something you add to a table so you can have a pointer to a particular LO oid in pg_largeobject. That being said there is nothing compelling you to store that info in a table, you can just create LO's in pg_largeobject. From the looks of it, and just a guess, the developers stored the oid's as integer's with the intent of doing integer::oid to get a particular LO back as needed. I would look at other information is stored in that table to see if helps determine what the LO's are for?
Also you might join the integer::oid values to the oid(loid) in pg_catalog to see if that table accounts for all of them?
I was able to do a detailed analysis of all user tables in the database, find all columns that contained numeric data with no decimals, and then do a a query from pg_largeobject with a NOT EXISTS clause for every table matching pglob.loid against the appropriate field(s) in the user tables.
I found 25794 LOIDs that could be DELETEd from the PGLOB table, totaling 3.4M rows.
select distinct loid
into OrphanedBLOBs
from pg_largeobject l
where NOT exists (select * from tbl1 cn where cn.noteid = l.loid)
and not exists (select * from tbl1 d where d.document = l.loid)
and not exists (select * from tbl1 d where d.reportid = l.loid)
I used that table to execute lo_unlink(loid) for each of the LOIDs.
I'm working with a huge Firebird database where tables have completely unreadable names like WTF$RANDOM_ABBREVIATION_6792 or RPG$RANDOM_ABBREVIATION_5462 where columns have names like "rid9312", "1NUM5", "2NUM4", "RNAME8".
I need to set them global aliases to be able to use them as a full-length table names like Document and column names like
Document.CreationDate instead of xecblob.DDATE4
or
TempDoc.MovingOrderID instead of TMP$LINKED_DOC_6101.DID6101
Altering the database, or a table, or a column might be a big problem because the records might be counted by millions and tens of millions, and more over that, a major part of the Delphi-written front-end for the database is bound to the table names and column names.
Is there a way to do that somehow?
The closest thing there is to a "global alias" is to create views. For example:
create view document
as
select
DDATE4 as creationdate
-- , other columns...
from xecblob;
or
create view document (creationdate /*, other column aliases... */)
as
select
DDATE4
-- , other columns...
from xecblob;
(personally, I find the first variant more readable)
This does require altering the database, but there is no real cost associated with that (it doesn't matter if the table contains no, one, thousands or millions of records).
I have create a redshift cluster and created a db inside.
My schema is new_schema
I have created 2 tables inside two tables inside table1, table2
My Question.
I want to list the datatypes of table1
I need to change the datatype of description which is inside the table1 which is of VARCHAR to TEXT
I have tried to list the datatypes of table1 with below query but nothing listing
SELECT * FROM PG_TABLE_DEF WHERE schemaname = 'new_schema';
A few possibilities as to why you are not seeing the expected results. Most likely is that new_schema isn't in your search_path. Pg_table_info only return info for tables in your search_path - see: https://docs.aws.amazon.com/redshift/latest/dg/r_PG_TABLE_DEF.html
Another possibility is that the tables have no data rows (no blocks assigned) and this can lead to incomplete info from some system tables.
Another possibility is that the tables were not committed by the creating session and being checked by a different session. Since you say that you are creating a new db this comes to mind.
Are the tables visible in svv_table_info?
Also the premise of changing varchar to text is a bit off. From https://docs.aws.amazon.com/redshift/latest/dg/r_Character_types.html#r_Character_types-text-and-bpchar-types
You can create an Amazon Redshift table with a TEXT column, but it is
converted to a VARCHAR(256) column that accepts variable-length values
with a maximum of 256 characters.
So it seems like the objective you are trying to achieve is a bit off.
We have got some DDLs for our schema. These DDLs create tables and indexes in a given tablespace. Something like:
CREATE TABLE mySchema.myTable
(
someField1 CHAR(2) NOT NULL ,
someField2 VARCHAR(70) NOT NULL
)
IN MY_TBSPC
INDEX IN MY_TBSPC;
We want to reuse this DDLs to run some integration tests using APACHE DERBY. The problem is that such syntax is not accepted by DERBY. Is there any way to define a kind of default tablespace for tables and indexes, so we can remove this 'IN TABLESPACE' statements.
There is no deterministic way of defining a "default" tablespace in DB2 (I'm assuming we're dealing with DB2 for LUW here). If the tablespaces are not explicitly indicated in the CREATE TABLE statement, the database manager will pick for table data the first tablespace with the suitable page size that you are authorized to use, and indexes will be stored in the same tablespace as data.
This means that if you only have one user tablespace it will always be used for both data and indexes, so in a way it becomes the default. However, if you have more than one tablespace with different page sizes you may end up with tables (and their indexes) in different tablespaces.
I know how partitioning in DB2 works but I am unaware about where this partition values exactly get stored. After writing a create partition query, for example:
CREATE TABLE orders(id INT, shipdate DATE, …)
PARTITION BY RANGE(shipdate)
(
STARTING '1/1/2006' ENDING '12/31/2006'
EVERY 3 MONTHS
)
after running the above query we know that partitions are created on order for every 3 month but when we run a select query the query engine refers this partitions. I am curious to know where this actually get stored, whether in the same table or DB2 has a different table where partition value for every table get stored.
Thanks,
table partitions in DB2 are stored in tablespaces.
For regular tables (if table partitioning is not used) table data is stored in a single tablespace (not considering LOBs).
For partitioned tables multiple tablespaces can used for its partitions.
This is achieved by the "" clause of the CREATE TABLE statement.
CREATE TABLE parttab
...
in TBSP1, TBSP2, TBSP3
In this example the first partition will be stored in TBSP1, the second in TBSP2, The third in TBSP3, the fourth in TBSP1 and so on.
Table partitions are named in DB2 - by default PART1 ..PARTn - and all these details can be looked up in the system catalog view SYSCAT.DATAPARTITIONS including the specified partition ranges.
See also http://www-01.ibm.com/support/knowledgecenter/SSEPGG_10.5.0/com.ibm.db2.luw.sql.ref.doc/doc/r0021353.html?cp=SSEPGG_10.5.0%2F2-12-8-27&lang=en
The column used as partitioning key can be looked up in syscat.datapartitionexpression.
There is also a long syntax for creating partitioned tables where partition names can be explizitly specified as well as the tablespace where the partitions will get stored.
For applications partitioned tables look like a single normal table.
Partitions can be detached from a partitioned table. In this case a partition is "disconnected" from the partitioned table and converted to a table without moving the data (or vice versa).
best regards
Michael
After a bit of research I finally figure it out and want to share this information with others, I hope it may come useful to others.
How to see this key values ? => For LUW (Linux/Unix/Windows) you can see the keys in the Table Object Editor or the Object Viewer Script tab. For z/OS there is an Object Viewer tab called "Limit Keys". I've opened issue TDB-885 to create an Object Viewer tab for LUW tables.
A simple query to check this values:
SELECT * FROM SYSCAT.DATAPARTITIONS
WHERE TABSCHEMA = ? AND TABNAME = ?
ORDER BY SEQNO
reference: http://www-01.ibm.com/support/knowledgecenter/SSEPGG_9.5.0/com.ibm.db2.luw.sql.ref.doc/doc/r0021353.html?lang=en
DB2 will create separate Physical Locations for each partition. So each partition will have its own Table-space. When you SELECT on this partitioned Table your SQL may directly go to a single partition or it may span across many depending on how your SQL is. Also, this may allow your SQL to run in parallel i.e. many TS can be accessed concurrently to speed up the SELECT.