"Albe Laurenz" <laurenz(dot)albe(at)wien(dot)gv(dot)at> writes:
> Tom Lane wrote:
>> I'm fairly skeptical that this is a real problem, and would prefer not
>> to complicate wrappers until we see some evidence from the field that
>> it's worth worrying about.
> If I have a table with 100000 rows and default_statistics_target
> at 100, then a sample of 30000 rows will be taken.
> If each row contains binary data of 1MB (an Image), then the
> data structure returned will use about 30 GB of memory, which
> will probably exceed maintenance_work_mem.
> Or is there a flaw in my reasoning?
Only that I don't believe this is a real-world scenario for a foreign
table. If you have a foreign table in which all, or even many, of the
rows are that wide, its performance is going to suck so badly that
you'll soon look for a different schema design anyway.
I don't want to complicate FDWs for this until it's an actual bottleneck
in real applications, which it may never be, and certainly won't be
until we've gone through a few rounds of performance refinement for
regards, tom lane
In response to
pgsql-hackers by date
|Next:||From: Simon Riggs||Date: 2012-04-30 15:29:17|
|Subject: Re: Analyzing foreign tables & memory problems|
|Previous:||From: Tom Lane||Date: 2012-04-30 15:12:56|
|Subject: Re: Patch: add timing of buffer I/O requests |