RMySQL fetch defaults to N=500?
Hi,
Jay Pfaffman wrote:
It appears that fetch() gets only the first 500 rows by default. I
don't see this in the documentation, but
timeinfo <- fetch(rs)
gets only 500 rows where
timeinfo <- fetch(rs,n=-1)
gets (correctly) 736 for the same query. Is this an undocumented
feature? I played with this data for an alarming amount of time
before I realized that I was missing a third of the data. I appear to
be using version 0.4-5. I'll upgrade to 0.4-6 Real Soon Now. My
first attempt failed for some reason.
Hmm, help(fetch) says
...
Usage:
fetch(res, n, ...)
Arguments:
res: a `resultSet' object. This object needs to be the result of a
`SELECT' or `SELECT'-like statement, as produced by `dbExec.'
or `dbExecStatement.' SQL statements such as `INSERT',
`DELETE', do not create result sets.
n: maximum number of records to retrieve per fetch. Use `n = -1'
to retrieve all pending records. Some implementations may
recognize other special values (RS-MySQL interprets `n = 0'
to mean "use whatever default was set in the call to
`MySQL').
... : any other database-engine specific arguments.
and if you follow the link to help(MySQL) ...
Usage:
MySQL(max.con = 10, fetch.default.rec = 500, force.reload = F)
Arguments:
max.con : maximum number of connections that we intended to have open.
This can be up to 100, a limit defined at compilation time.
Strictly speaking this limit applies to MySQL servers, but
clients can have (at least in theory) more than this.
fetch.default.rec: number of records to fetch at one time from the
database. (The `fetch' method uses this number as a default.)
force.reload: should we reload (reinitialize) the client code? Setting
this to `TRUE' allows you to change default settings. Notice
that all connections should be closed before re-loading.
so I think it's clear (but I'm open to suggestions).
Regards,
-- Jay Pfaffman pfaffman at relaxpc.com +1-415-821-7507 (H) +1-415-810-2238 (M) -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._
David A. James Statistics Research, Room 2C-253 Phone: (908) 582-3082 Bell Labs, Lucent Technologies Fax: (908) 582-3340 Murray Hill, NJ 09794-0636 -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._