pgsql: Use correct format placeholder for pids

Use correct format placeholder for pids Should be signed, not unsigned. Branch -- master Details --- https://git.postgresql.org/pg/commitdiff/640b91c3ed24002b34c7226fb51ef9176fb72713 Modified Files -- src/backend/postmaster/autovacuum.c | 2 +- src/backend/postmaster/

pgsql: Document LP_DEAD accounting issues in VACUUM.

Document LP_DEAD accounting issues in VACUUM. Document VACUUM's soft assumption that any LP_DEAD items encountered during pruning will become LP_UNUSED items before VACUUM finishes up. This is integral to the accounting used by VACUUM to generate its final report on the table to the stats collecto