has_idx: Check if a table has an index

In f-hafner/magutils: Utilities for loading data from MAG-Proquest database

Check if a table has an index

Description

Check if the table holds an index on the specified columns and optionally check whether it is unique.

Usage

has_idx(conn, on_tbl, on_cols, keep_unique = FALSE, temp = FALSE)

Arguments

conn	An object of class SQLiteConnection to a sqlite database.
on_tbl	A table in the database.
on_cols	A character vector with the columns to check.
keep_unique	A logical. Additionally check if the index has the UNIQUE constraint. Default is FALSE.
temp	Should sqlite_temp_master be queried, instead of sqlite_master? Default is FALSE. This can be useful when looking for temporary tables and indexes on them.

Details

The function only checks exact matching of on_cols, that is, the order of columns in on_cols needs to correspond to the order of columns in the CREATE INDEX statement: If on_cols = c("col1", "col2"), but the database has "CREATE UNIQUE INDEX idx1 ON mytable(col2, col1)", the function will return FALSE.

Value

A logical.

Examples

conn <- connect_to_db(db_example("AcademicGraph.sqlite"))
has_idx(conn, "author_output", "AuthorId", keep_unique = TRUE)

f-hafner/magutils documentation built on Sept. 20, 2023, 5:05 a.m.