topo_sort_tables {rquery} | R Documentation |
Topologically sort join plan so values are available before uses.
Description
Depends on igraph
package.
Please see vignette('DependencySorting', package = 'rquery')
and vignette('joinController', package= 'rquery')
for more details.
Usage
topo_sort_tables(columnJoinPlan, leftTableName, ...)
Arguments
columnJoinPlan |
join plan |
leftTableName |
which table is left |
... |
force later arguments to bind by name |
Value
list with dependencyGraph and sorted columnJoinPlan
Examples
if (requireNamespace("DBI", quietly = TRUE) && requireNamespace("RSQLite", quietly = TRUE) &&
requireNamespace('igraph', quietly = TRUE)) {
# note: employeeanddate is likely built as a cross-product
# join of an employee table and set of dates of interest
# before getting to the join controller step. We call
# such a table "row control" or "experimental design."
my_db <- DBI::dbConnect(RSQLite::SQLite(), ":memory:")
RSQLite::initExtension(my_db)
tDesc <- example_employee_date(my_db)
columnJoinPlan <- build_join_plan(tDesc, check= FALSE)
# unify keys
columnJoinPlan$resultColumn[columnJoinPlan$resultColumn=='id'] <- 'eid'
# look at plan defects
print(paste('problems:',
inspect_join_plan(tDesc, columnJoinPlan)))
# fix plan
sorted <- topo_sort_tables(columnJoinPlan, 'employeeanddate')
print(paste('problems:',
inspect_join_plan(tDesc, sorted$columnJoinPlan)))
print(plot(sorted$dependencyGraph))
DBI::dbDisconnect(my_db)
my_db <- NULL
}
[Package rquery version 1.4.99 Index]