U++ framework: U++ SQL » Acquiring large record

Home » U++ Library support » U++ SQL » Acquiring large record

Show: Today's Messages :: Polls :: Message Navigator
E-mail to friend

Acquiring large record [message #23017]

Tue, 08 September 2009 00:02

Mindtraveller
Messages: 917
Registered: August 2007
Location: Russia, Moscow rgn.

Experienced Contributor

Is there a way to acquire large record (300+ MB) not putting it into memory at once? It would be great to make something like stream to get data through relatively small data chunks.

Report message to a moderator

Re: Acquiring large record [message #23027 is a reply to message #23017]

Tue, 08 September 2009 23:58

Mindtraveller
Messages: 917
Registered: August 2007
Location: Russia, Moscow rgn.

Experienced Contributor

The problem appears when one tries to hold/fetch i.e. large files in/from database. Not going into detail, the maximum allowed SQL transaction size is commonly no more than 1 MB.
Just in case someone needs to store large blobs in a database too, publishing a solution. The idea is to have separate table with blob column. So you divide your large file into ~512 KB pieces and keep them as records sequence in the table. Each time you need this big blob, you have to fetch it with many transactions, piece by piece.

Report message to a moderator

Re: Acquiring large record [message #23045 is a reply to message #23027]

Thu, 10 September 2009 14:05

mirek
Messages: 14291
Registered: November 2005

Ultimate Member

Mindtraveller wrote on Tue, 08 September 2009 17:58

The problem appears when one tries to hold/fetch i.e. large files in/from database. Not going into detail, the maximum allowed SQL transaction size is commonly no more than 1 MB.

Depends on DB...

Quote:

Just in case someone needs to store large blobs in a database too, publishing a solution. The idea is to have separate table with blob column. So you divide your large file into ~512 KB pieces and keep them as records sequence in the table. Each time you need this big blob, you have to fetch it with many transactions, piece by piece.

Well, there is a support for BLOBs for Oracle. These AFAIK tend to be quite DB specific I am afraid and nobody investigated/implemented these things in other DBs. But when you do, I guess looking on how it is done (interface-wise) in Oracle should help...

Report message to a moderator

Previous Topic:	Postgres library improvements
Next Topic:	Postgres and CurrVal

Goto Forum:

-=] Back to Top [=-

[ Syndicate this forum (XML) ] [

] [

]

Current Time: Mon Sep 14 02:45:33 GMT+2 2026

Total time taken to generate the page: 0.00890 seconds