Greetings, * Hubert Zhang (hzh...@pivotal.io) wrote: > For very large databases, the dbsize function `pg_database_size_name()` > etc. could be quite slow, since it needs to call `stat()` system call on > every file in the target database.
I agree, it'd be nice to improve this. > We proposed a new solution to accelerate these dbsize functions which check > the disk usage of database/schema/table. The new functions avoid to call > `stat()` system call, and instead store the disk usage of database objects > in user tables(called diskquota.xxx_size, xxx could be db/schema/table). > Checking the size of database 'postgres' could be converted to the SQL > query `select size from diskquota.db_size where name = `postgres``. This seems like an awful lot of work though. I'd ask a different question- why do we need to stat() every file? In the largest portion of the system, when it comes to tables, indexes, and such, if there's a file 'X.1', you can be pretty darn sure that 'X' is 1GB in size. If there's a file 'X.245' then you can know that there's 245 files (X, X.1, X.2, X.3 ... X.244) that are 1GB in size. Maybe we should teach pg_database_size_name() about that? Thanks! Stephen
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