memory_contexts

memory_contexts

Runnable examples of PgMemoryContext lifecycle and how memory contexts interact with SRFs and bgworkers.

Files

File	What it shows
basics.rs	Create a child PgMemoryContexts, switch_to for scoped allocation, reset to reclaim, anti-pattern (use-after-reset) explained in module docs.
srf_per_call.rs	Two SRFs — one streaming (SetOfIterator), one materialized (TableIterator) — with notes on multi_call_memory_ctx vs per_query_ctx and what pgrx handles for you.
bgworker_state.rs	Bgworker that allocates its long-lived counter under TopMemoryContext. Not exercised by pg_test; run manually with cargo pgrx run pg17 memory_contexts after adding the crate to shared_preload_libraries.

Running

cargo pgrx test pg17 -p memory_contexts

The bgworker example does not run under cargo pgrx test. To exercise it:

1. Add to ${PGRX_HOME}/data-17/postgresql.conf:

   shared_preload_libraries = 'memory_contexts'
   

2. cargo pgrx run pg17 memory_contexts
3. Watch the postmaster log for memory_contexts demo worker tick N lines.