begin

Start a transaction: $env->begin for a write transaction, $env->begin(MDB_RDONLY) for a read one.

Synopsis

my $txn = $env->begin;
my $r   = $env->begin(MDB_RDONLY);

What you get back

A Peta::LMDB::Txn. A read transaction sees the data as it was when it began, however long it lives, and never waits. A write transaction waits while another one - in this process or another - is live, as there is one writer at a time.

Edge cases

• A transaction that goes out of scope without commit is aborted: its writes are discarded.

• A long-lived read transaction keeps the pages it sees from being reused, so the file grows while writers work; end read transactions (or reset them) when done.

See also

• Peta::LMDB::Txn - what a transaction does

• stat - the size of the unnamed database