List the named databases in an environment

Reports the named databases visible to this transaction. Visibility is the transaction's own: a database this transaction created is listed immediately, and one it deleted is gone immediately, both before any commit. What other transactions see is decided when this one commits or aborts — until then they see neither the creation nor the deletion.

Usage

mdbx_dbi_list(txn, as = c("character", "raw"))

Arguments

txn

An mdbx_txn object, from mdbx_txn_begin().

as

"character" (the default) to decode names as UTF-8 text, or "raw" for a list of raw vectors.

Value

A character vector of names, or a list of raw vectors if as = "raw". Empty when the environment has only the main database.

Details

That makes this the way to ask whether a database exists without handling an error, which is what mdbx_dbi_open() raises for a name that was never created.

Names are bytes, like keys, so a name that is not valid UTF-8 text needs as = "raw". The unnamed main database is not listed, having no name.

See also

mdbx_dbi_open()

Examples

path <- tempfile(fileext = ".mdbx")
env <- mdbx_env_open(path, max_dbs = 8)

mdbx_with_write(env, function(txn) {
  mdbx_dbi_open(txn, "files", create = TRUE)
  mdbx_dbi_open(txn, "metadata", create = TRUE)
})
#> <mdbx_dbi> metadata 

mdbx_with_read(env, function(txn) mdbx_dbi_list(txn))
#> [1] "files"    "metadata"

mdbx_env_close(env)
unlink(c(path, paste0(path, "-lck")))