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#' Backend: Snowflake
#'
#' @description
#' See `vignette("translation-function")` and `vignette("translation-verb")` for
#' details of overall translation technology.
#'
#' Use `simulate_snowflake()` with `lazy_frame()` to see simulated SQL without
#' converting to live access database.
#'
#' @name backend-snowflake
#' @aliases NULL
#' @examples
#' library(dplyr, warn.conflicts = FALSE)
#'
#' lf <- lazy_frame(a = TRUE, b = 1, c = 2, d = "z", con = simulate_snowflake())
#' lf %>% transmute(x = paste0(d, " times"))
NULL
#' @export
sql_translation.Snowflake <- function(con) {
sql_variant(
sql_translator(
.parent = base_odbc_scalar,
log10 = function(x) sql_expr(log(10, !!x)),
grepl = snowflake_grepl,
round = snowflake_round,
paste = snowflake_paste(" "),
paste0 = snowflake_paste(""),
str_c = function(..., sep = "", collapse = NULL) {
if (!is.null(collapse)) {
cli_abort(c(
"{.arg collapse} not supported in DB translation of {.fn str_c}.",
i = "Please use {.fn str_flatten} instead."
))
}
sql_call2("CONCAT_WS", sep, ...)
},
str_locate = function(string, pattern) {
sql_expr(POSITION(!!pattern, !!string))
},
# REGEXP on Snowflaake "implicitly anchors a pattern at both ends", which
# str_detect does not. Left- and right-pad `pattern` with .* to get
# str_detect-like behavior
str_detect = function(string, pattern, negate = FALSE) {
if (isTRUE(negate)) {
sql_expr(!(((!!string)) %REGEXP% (".*" || (!!pattern) || ".*")))
} else {
sql_expr(((!!string)) %REGEXP% (".*" || (!!pattern) || ".*"))
}
},
# On Snowflake, REGEXP_REPLACE is used like this:
# REGEXP_REPLACE( <subject> , <pattern> [ , <replacement> ,
# <position> , <occurrence> , <parameters> ] )
# so we must set <occurrence> to 1 if not replacing all. See:
# https://docs.snowflake.com/en/sql-reference/functions/regexp_replace.html
# Also, Snowflake needs backslashes escaped, so we must increase the
# level of escaping by 1
str_replace = function(string, pattern, replacement) {
pattern <- gsub("\\", "\\\\", pattern, fixed = TRUE)
sql_expr(regexp_replace(!!string, !!pattern, !!replacement, 1, 1))
},
str_replace_all = function(string, pattern, replacement) {
pattern <- gsub("\\", "\\\\", pattern, fixed = TRUE)
sql_expr(regexp_replace(!!string, !!pattern, !!replacement))
},
str_remove = function(string, pattern) {
pattern <- gsub("\\", "\\\\", pattern, fixed = TRUE)
sql_expr(regexp_replace(!!string, !!pattern, "", 1, 1))
},
str_remove_all = function(string, pattern) {
pattern <- gsub("\\", "\\\\", pattern, fixed = TRUE)
sql_expr(regexp_replace(!!string, !!pattern))
},
str_trim = function(string) {
sql_expr(trim(!!string))
},
str_squish = function(string) {
sql_expr(regexp_replace(trim(!!string), "\\\\s+", " "))
},
# lubridate functions
# https://docs.snowflake.com/en/sql-reference/functions-date-time.html
day = function(x) {
sql_expr(EXTRACT(DAY %FROM% !!x))
},
mday = function(x) {
sql_expr(EXTRACT(DAY %FROM% !!x))
},
wday = function(x, label = FALSE, abbr = TRUE, week_start = NULL) {
if (!label) {
week_start <- week_start %||% getOption("lubridate.week.start", 7)
offset <- as.integer(7 - week_start)
sql_expr(EXTRACT("dayofweek", DATE(!!x) + !!offset) + 1)
} else if (label && !abbr) {
sql_expr(
DECODE(
EXTRACT("dayofweek", !!x),
1, "Monday",
2, "Tuesday",
3, "Wednesday",
4, "Thursday",
5, "Friday",
6, "Saturday",
0, "Sunday"
)
)
} else if (label && abbr) {
sql_expr(DAYNAME(!!x))
} else {
abort("Unrecognized arguments to `wday`")
}
},
yday = function(x) sql_expr(EXTRACT("dayofyear", !!x)),
week = function(x) {
sql_expr(FLOOR((EXTRACT("dayofyear", !!x) - 1L) / 7L) + 1L)
},
isoweek = function(x) sql_expr(EXTRACT("weekiso", !!x)),
month = function(x, label = FALSE, abbr = TRUE) {
if (!label) {
sql_expr(EXTRACT("month", !!x))
} else {
if (abbr) {
sql_expr(MONTHNAME(!!x))
} else {
sql_expr(
DECODE(
EXTRACT("month", !!x),
1, "January",
2, "February",
3, "March",
4, "April",
5, "May",
6, "June",
7, "July",
8, "August",
9, "September",
10, "October",
11, "November",
12, "December"
)
)
}
}
},
quarter = function(x, with_year = FALSE, fiscal_start = 1) {
if (fiscal_start != 1) {
abort("`fiscal_start` is not supported in Snowflake translation. Must be 1.")
}
if (with_year) {
sql_expr((EXTRACT("year", !!x) || "." || EXTRACT("quarter", !!x)))
} else {
sql_expr(EXTRACT("quarter", !!x))
}
},
isoyear = function(x) {
sql_expr(EXTRACT("year", !!x))
},
seconds = function(x) {
build_sql("INTERVAL '", x, " second'")
},
minutes = function(x) {
build_sql("INTERVAL '", x, " minute'")
},
hours = function(x) {
build_sql("INTERVAL '", x, " hour'")
},
days = function(x) {
build_sql("INTERVAL '", x, " day'")
},
weeks = function(x) {
build_sql("INTERVAL '", x, " week'")
},
months = function(x) {
build_sql("INTERVAL '", x, " month'")
},
years = function(x) {
build_sql("INTERVAL '", x, " year'")
},
# https://docs.snowflake.com/en/sql-reference/functions/date_trunc.html
floor_date = function(x, unit = "seconds") {
unit <- arg_match(unit,
c("second", "minute", "hour", "day", "week", "month", "quarter", "year",
"seconds", "minutes", "hours", "days", "weeks", "months", "quarters", "years")
)
sql_expr(DATE_TRUNC(!!unit, !!x))
}
),
sql_translator(
.parent = base_agg,
cor = sql_aggregate_2("CORR"),
cov = sql_aggregate_2("COVAR_SAMP"),
all = sql_aggregate("BOOLAND_AGG", "all"),
any = sql_aggregate("BOOLOR_AGG", "any"),
sd = sql_aggregate("STDDEV", "sd"),
str_flatten = function(x, collapse = "") {
sql_expr(LISTAGG(!!x, !!collapse))
}
),
sql_translator(
.parent = base_win,
cor = win_aggregate_2("CORR"),
cov = win_aggregate_2("COVAR_SAMP"),
all = win_aggregate("BOOLAND_AGG"),
any = win_aggregate("BOOLOR_AGG"),
sd = win_aggregate("STDDEV"),
str_flatten = function(x, collapse = "") {
win_over(
sql_expr(LISTAGG(!!x, !!collapse)),
partition = win_current_group(),
order = win_current_order()
)
}
)
)
}
#' @export
#' @rdname backend-snowflake
simulate_snowflake <- function() simulate_dbi("Snowflake")
# There seems to be no concept of ANALYZE TABLE in Snowflake. I searched for
# functions that performed similar operations, and found none.
# Link to full list: https://docs.snowflake.com/en/sql-reference/sql-all.html
#' @export
sql_table_analyze.Snowflake <- function(con, table, ...) {}
snowflake_grepl <- function(pattern, x, ignore.case = FALSE, perl = FALSE, fixed = FALSE, useBytes = FALSE) {
# https://docs.snowflake.com/en/sql-reference/functions/regexp.html
if (perl || fixed || useBytes || ignore.case) {
cli_abort("{.arg {c('perl', 'fixed', 'useBytes', 'ignore.case')}} parameters are unsupported.")
}
# REGEXP on Snowflaake "implicitly anchors a pattern at both ends", which
# grepl does not. Left- and right-pad `pattern` with .* to get grepl-like
# behavior
sql_expr(((!!x)) %REGEXP% (".*" || !!paste0('(', pattern, ')') || ".*"))
}
snowflake_round <- function(x, digits = 0L) {
digits <- as.integer(digits)
sql_expr(round(((!!x)) %::% FLOAT, !!digits))
}
# On Snowflake, CONCAT_WS is null if any of its arguments are null. Paste
# is implemented here to avoid this behavior.
snowflake_paste <- function(default_sep) {
function(..., sep = default_sep, collapse = NULL) {
check_collapse(collapse)
sql_call2(
"ARRAY_TO_STRING",
sql_call2("ARRAY_CONSTRUCT_COMPACT", ...), sep
)
}
}
utils::globalVariables(c("%REGEXP%", "DAYNAME", "DECODE", "FLOAT", "MONTHNAME", "POSITION", "trim"))
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