频繁创建临时表导致 pg_class OID 耗尽

Question

Does PostgreSQL have mechanism of dealing with rapidly growing OID counter on pg_catalog.pg_class table especially when that counter ticks over the maximum number of unique integer values.

I have a very busy database with many concurrent processes that rely on frequently creating temporary tables via CREATE TEMP TABLE ... ON COMMIT DROP . Most of transactions are very short and temp tables are automatically dropped at the end but the counter on pg_catalog.pg_class.oid is rapidly moving forward.

What is going to happen when that counter makes a complete "circle around the integer"? Will it intelligently avoid collisions and if so will it come at a cost of performance or other negative side effects?

I perused PostgreSQL documentation and found information about OID transaction wraparound but no references to what happens when pg_catalog tables exhaust all IODs.

Answer 1

OID wraparound is not your worry. PostgreSQL will avoid collisions when assigning and OID to a table.

You problem may be table bloat. Whenever a temporary table is created and removed, this causes dead tuples in the pg_attributes tables. So you should make sure that that catalog table is vacuumed aggressively (low autovacuum_vacuum_cost_delay ) so that it doesn't bloat.