docdb_exists: Check if container exists in database
Description
Check if container exists in database
Usage
docdb_exists(src, key, ...)
Value
(logical) TRUE or FALSE to indicate
existence of container key in database
Arguments
src
Source object, result of call to any of functions
src_mongo(), src_sqlite(), src_elastic(), src_couchdb()
or src_postgres()
key
(character) A key as name of the container
(corresponds to parameter collection for MongoDB,
dbname for CouchDB, index for Elasticsearch and to
a table name for SQLite and for PostgreSQL)