join hangs on empty suffix

join_suffix.R

library(dplyr)

a = data.frame(id=1:3, x=1:3)

## local join: works as expected

inner_join(a, a, by="id", suffix=c(".1", ".2"))
#   id x.1 x.2
# 1  1   1   1
# 2  2   2   2
# 3  3   3   3
inner_join(a, a, by="id", suffix=c("", ".2"))
#   id x x.2
# 1  1 1   1
# 2  2 2   2
# 3  3 3   3
inner_join(a, a, by="id", suffix=c("1.", ""))
#   id x1. x
# 1  1   1 1
# 2  2   2 2
# 3  3   3 3


## db connection: empty suffix hangs join

con = DBI::dbConnect(RSQLite::SQLite(), path = ":memory:")
copy_to(con, a, "a", temporary=F)
a_db = tbl(con, "a")

inner_join(a_db, a_db, by="id", suffix=c(".1", ".2"))
# # Source:   lazy query [?? x 3]
# # Database: sqlite 3.19.3 []
#      id   x.1   x.2
#   <int> <int> <int>
# 1     1     1     1
# 2     2     2     2
# 3     3     3     3
inner_join(a_db, a_db, by="id", suffix=c("", ".2")) 
# hangs until killed
inner_join(a_db, a_db, by="id", suffix=c("1.", ""))
# hangs until killed


## LHS local, RHS db: works as expected

inner_join(a, a_db, copy=TRUE, by="id", suffix=c(".1", ".2"))
#   id x.1 x.2
# 1  1   1   1
# 2  2   2   2
# 3  3   3   3
inner_join(a, a_db, copy=TRUE, by="id", suffix=c("", ".2"))
#   id x x.2
# 1  1 1   1
# 2  2 2   2
# 3  3 3   3
inner_join(a, a_db, copy=TRUE, by="id", suffix=c("1.", ""))
#   id x1. x
# 1  1   1 1
# 2  2   2 2
# 3  3   3 3


## LHS db, RHS local: empty suffix hangs join

inner_join(a_db, a, copy=TRUE, by="id", suffix=c(".1", ".2"))
# Source:   lazy query [?? x 3]
# Database: sqlite 3.19.3 []
#      id   x.1   x.2
#   <int> <int> <int>
# 1     1     1     1
# 2     2     2     2
# 3     3     3     3
inner_join(a_db, a, copy=TRUE, by="id", suffix=c("", ".2"))
# hangs until killed
inner_join(a_db, a, copy=TRUE, by="id", suffix=c("1.", ""))
# hangs until killed