sqlite3 - SQLite VACUUM in DB opened from multiple processes -

i’ve 2 questions sqlite vacuum (and possibly wal):

• if multiple processes have db open, sql statements in processes need finalized vacuum succeed?

• why vacuum sometime not have effect (no space reclaimed) sqlite return sqlite3_ok?

a bit more details problem:

i’ve database in wal mode accessed 2 processes. @ point, user has choice of dropping data database. because database can opened multiple processes, delete records , run vacuum reclaim disk space (instead of closing connection , deleting file).

the problem if 2 processes have db connection opened, vacuum 1 of processes returns ok, not reclaim space really.

i think happens vacuum won’t succeed till there’s outstanding sql statement process. problem not want make 2 processes aware of each other.

what considering doing vacuum both processes, whichever closes connection last (upon user request drop data), takes care of space reclamation. considering auto_vacuum (i aware of limitations, deletes not frequent on database.

the documentation says:

a vacuum fail if there open transaction, or if there 1 or more active sql statements when run.

just other kind of database modification, writable transaction requires no other read or write transaction active; requires statements reset or finalized.

when in wal mode, write transaction not blocked other read transactions, requires old data kept. should initiate truncate checkpoint in addition vacuum.

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the easiest way handle not run vacuum @ all; free space reused later.