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First stab at databricks support (#1379)
Fixes #1377
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,130 @@ | ||
| #' Backend: Databricks Spark SQL | ||
| #' | ||
| #' @description | ||
| #' See `vignette("translation-function")` and `vignette("translation-verb")` for | ||
| #' details of overall translation technology. Key differences for this backend | ||
| #' are better translation of statistical aggregate functions | ||
| #' (e.g. `var()`, `median()`) and use of temporary views instead of temporary | ||
| #' tables when copying data. | ||
| #' | ||
| #' Use `simulate_spark_sql()` with `lazy_frame()` to see simulated SQL without | ||
| #' converting to live access database. | ||
| #' | ||
| #' @name backend-spark-sql | ||
| #' @aliases NULL | ||
| #' @examples | ||
| #' library(dplyr, warn.conflicts = FALSE) | ||
| #' | ||
| #' lf <- lazy_frame(a = TRUE, b = 1, d = 2, c = "z", con = simulate_spark_sql()) | ||
| #' | ||
| #' lf %>% summarise(x = median(d, na.rm = TRUE)) | ||
| #' lf %>% summarise(x = var(c, na.rm = TRUE), .by = d) | ||
| #' | ||
| #' lf %>% mutate(x = first(c)) | ||
| #' lf %>% mutate(x = first(c), .by = d) | ||
| NULL | ||
|
|
||
| #' @export | ||
| #' @rdname backend-spark-sql | ||
| simulate_spark_sql <- function() simulate_dbi("Spark SQL") | ||
|
|
||
| #' @export | ||
| `dbplyr_edition.Spark SQL` <- function(con) { | ||
| 2L | ||
| } | ||
|
|
||
| #' @export | ||
| `sql_translation.Spark SQL` <- function(con) { | ||
| sql_variant( | ||
| base_odbc_scalar, | ||
| sql_translator(.parent = base_odbc_agg, | ||
| var = sql_aggregate("VARIANCE", "var"), | ||
| quantile = sql_quantile("PERCENTILE"), | ||
| median = sql_aggregate("MEDIAN"), | ||
| first = function(x, na_rm = FALSE) { | ||
| check_na_rm(na_rm) | ||
| glue_sql2(sql_current_con(), "FIRST({.val x})") | ||
| }, | ||
| last = function(x, na_rm = FALSE) { | ||
| check_na_rm(na_rm) | ||
| glue_sql2(sql_current_con(), "LAST({.val x})") | ||
| }, | ||
| ), | ||
| sql_translator(.parent = base_odbc_win, | ||
| var = win_aggregate("VARIANCE"), | ||
| quantile = sql_quantile("PERCENTILE", window = TRUE), | ||
| median = win_aggregate("MEDIAN"), | ||
| first = function(x, order_by = NULL, na_rm = FALSE) { | ||
| sql_nth(x, 1L, order_by = order_by, na_rm = na_rm, ignore_nulls = "bool") | ||
| }, | ||
| last = function(x, order_by = NULL, na_rm = FALSE) { | ||
| sql_nth(x, Inf, order_by = order_by, na_rm = na_rm, ignore_nulls = "bool") | ||
| }, | ||
| nth = function(x, n, order_by = NULL, na_rm = FALSE) { | ||
| sql_nth(x, n, order_by = order_by, na_rm = na_rm, ignore_nulls = "bool") | ||
| }, | ||
| ) | ||
| ) | ||
| } | ||
|
|
||
| #' @export | ||
| `sql_table_analyze.Spark SQL` <- function(con, table, ...) { | ||
| # https://docs.databricks.com/en/sql/language-manual/sql-ref-syntax-aux-analyze-table.html | ||
| glue_sql2(con, "ANALYZE TABLE {.tbl table} COMPUTE STATISTICS") | ||
| } | ||
|
|
||
| #' @export | ||
| `supports_window_clause.Spark SQL` <- function(con) { | ||
| TRUE | ||
| } | ||
|
|
||
| #' @export | ||
| `db_copy_to.Spark SQL` <- function(con, | ||
| table, | ||
| values, | ||
| ..., | ||
| overwrite = FALSE, | ||
| types = NULL, | ||
| temporary = TRUE, | ||
| unique_indexes = NULL, | ||
| indexes = NULL, | ||
| analyze = TRUE, | ||
| in_transaction = FALSE) { | ||
|
|
||
| if (!temporary) { | ||
| cli::cli_abort("Spark SQL only support temporary tables") | ||
| } | ||
|
|
||
| sql <- sql_values_subquery(con, values, types = types, lvl = 1) | ||
| db_compute(con, table, sql, overwrite = overwrite) | ||
| } | ||
|
|
||
| #' @export | ||
| `db_compute.Spark SQL` <- function(con, | ||
| table, | ||
| sql, | ||
| ..., | ||
| overwrite = FALSE, | ||
| temporary = TRUE, | ||
| unique_indexes = list(), | ||
| indexes = list(), | ||
| analyze = TRUE, | ||
| in_transaction = FALSE) { | ||
|
|
||
| if (!temporary) { | ||
| cli::cli_abort("Spark SQL only support temporary tables") | ||
| } | ||
|
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||
| table <- as_table_ident(table) | ||
| sql <- glue_sql2( | ||
| con, | ||
| "CREATE ", if (overwrite) "OR REPLACE ", | ||
| "TEMPORARY VIEW {.tbl {table}} AS \n", | ||
| "{.from {sql}}" | ||
| ) | ||
| DBI::dbExecute(con, sql) | ||
|
|
||
| table | ||
| } | ||
|
|
||
| utils::globalVariables("regexp_replace") |
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