[Labs-l] dimension well my queries for very large tables like pagelinks - Tool Labs

Fri Mar 13 16:59:09 UTC 2015

Hello guys,

I have a question regarding Tool Labs. I am doing research on links and
although I know very well what I am looking for I struggle in how to get it
effectively...

I need to know your opinion because you know very well the system and
what's feasible and what is not.

I explain you what I need to do:
I have a list of articles for different languages which I need to check
their pagelinks and see where they point to and from where they point at
them.

I now do a query for each article id in this list of articles, which goes
from 80000 in some wikipedias to 300000 in other and more. I have to do it
several times and it is very time consuming (several days). I wish I could
only count the total of links for each case but I need to see only some of
the links per article.

I was thinking about getting all pagelinks and iterating using python
(which is the language I use for all this). This would be much faster
because I'd save all the queries, one per article, I am doing now. But
pagelinks table has millions of rows and I cannot load that because mysql
would die. I could buffer, but I haven't tried if it works also.

I am considering creating a personal table in the database with titles,
ids, and inner joining to just obtain the pagelinks for these 300.000
articles. With this I would just retrieve 20% of the database instead of
the 100%. That would be maybe 8M rows sometimes (page_title or page_id, one
of both per row), or even more... loaded into python dictionaries and
lists. Would that be a problem...? I have no idea of how much RAM this
implies and how much I can use in Tool labs.

I am totally lost when I get these problems related to scale...I thought
about writing to the IRC channel but I thought it was maybe too long and
too specific. If you give me any hint that would really help.

Thank you very much!

Cheers,

Marc Miquel
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