There are few limitations which we have on Fastload.
These limitations are necessary for Fastload to load data with the lightning fast speed into tables.
- NO SECONDARY INDEXES ARE ALLOWED ON TARGET TABLE – Fastload can load tables only with primary indexes defined on it. If we have a secondary index on the table then Fastload will not load that table. We get a error message if we load such type of table –
If secondary index exist already, we need to drop them.
After loading the table through Fastload we can easily recreate them on the table.
CREATE INDEX (Column-name/s) ON dbname.tablename —— > creates Non Unique Secondary Index
or
CREATE UNIQUE INDEX (Column-name/s) ON dbname.tablename —— > creates Unique Secondary Index
- NO REFERENTIAL INTEGRITY IS ALLOWED – Fastload cannot load data into tables that are defined with Referential Integrity (RI). This would require too much system checking to prevent referential constraints to a different table
- NO TRIGGERS ARE ALLOWED AT LOAD TIME – Fastload is much too focused on speed to pay attention to the needs of other tables, which is what Triggers are all about. Additionally, these require more than one AMP and more than one table. Fastload does one table only. Simply ALTER the Triggers to the DISABLED status prior to using Fastload.
- DUPLICATE ROWS ARE NOT SUPPORTED – Multiset tables are a table that allow duplicate rows — that is when the values in every column are identical. When Fastload finds duplicate rows, they are discarded. While Fastload can load data into a multi-set table, Fastload will not load duplicate rows into a multi-set table because Fastload discards duplicate rows
Related Post -Teradata Utilities : FASTLOAD – Part 1
7 comments
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Vijay says:
August 23, 2012 at 10:16 am (UTC 0)
Why Fast load(and mload) doesn’t support SI ?
admin says:
August 23, 2012 at 11:04 am (UTC 0)
As you must be knowing that SI requires a sub table for storing SI values. Now the whole purpose of using FLOAD or MLOAD is the SPEED by which we transfer files from client to host system. So this loading of subtable is a overhead for these utilities and they loose the performance edge because of this loading. That’s why SI is not supported by FLOAD and MLOAD.
Though MLOAD supports only NUSI becuase its subtable resides in the same AMP as that of base row.
for more on SI please refer – http://www.teradatatech.com/?p=815
KrisV says:
May 13, 2012 at 8:50 pm (UTC 0)
How to release a fastload lock on a table without the table being dropped and recreated.
admin says:
May 14, 2012 at 9:10 am (UTC 0)
if somehow fastload fails and our table has been locked by that session -
RDBMS error 2652: Operation not allowed: _db_._table_ is being Loaded.
then there is 1 possible things which we can do to release fastload lock without dropping the actual table
Run the dummy fastload script which contains only begin loading and end loading. e.g.
logon serverid/username,password;
begin loading ……. ;
end loading;
logoff;
KrisV says:
May 13, 2012 at 8:49 pm (UTC 0)
How to release a fastload lock on a table without the table being dropped and recreated?
swathi says:
April 26, 2012 at 1:03 pm (UTC 0)
Hi,
If possible can you please explain about secondary index and usage of secondary index while primary index is present.
admin says:
April 26, 2012 at 2:38 pm (UTC 0)
very soon i’ll post about SI
for now you can assume that SI is the next possible path to reach the particular row in AMP, if we cant achieve that with PI.