Hello Simon, Hello everyone,
I have a problem with retrieving database-queries chunkwise. In my query
(Postgresql-Database, Postgres-Version 9.1) dbHasCompleted seems to
always return TRUE.
dbGetQuery works for smaller tables, but not for the whole query, since
then a Heap-Overflow-Error will occur (and a Error:
"java.lang.OutOfMemoryError: GC overhead limit exceeded" when trying to
set a larger size).
Does anybody else have or had this problem?
All the best
Julian
######## adapted Example from help (?dbHasCompleted ), Works #######
require("RSQLite")
con <- dbConnect(RSQLite::SQLite(), ":memory:")
dbWriteTable(con, "mtcars", mtcars)
# Fetch all results
res <- dbSendQuery(con, "SELECT * FROM mtcars WHERE cyl = 4")
dbFetch(res)
dbClearResult(res)
# Fetch in chunks
res <- dbSendQuery(con, "SELECT * FROM mtcars")
dbHasCompleted(res) ## RETURNS FALSE !!!
while (!dbHasCompleted(res)) {
chunk <- fetch(res, 10)
print(nrow(chunk))
}
dbClearResult(res)
dbDisconnect(con)
########## My Code, lamentably not reproducible because of needed
Postgres-Server, not working #########
# Connect to Postgres-Database
res2 <- dbSendQuery(Postgres_con,
"select id from mytable limit 1000;"
)
dbHasCompleted(res2) ##RETURNS TRUE!
while (!dbHasCompleted(res2)) {
chunk <- fetch(res2, 10 )
rbind(dk, chunk)
}
try({
dbClearResult(res2)
rm(chunk,res2)
})
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