# Source Atlas PostgreSQL functions, and where this site explains each one: the reverse of a code trail. > Canonical URL: https://sudohulk.com/atlas > PostgreSQL: 18.3 (`REL_18_3`) > As JSON: https://sudohulk.com/atlas.json > Author: Vignesh Kumar A > Licence: CC BY 4.0. Quote freely, cite the canonical URL. --- Every line is looked up in the source this site commits at that release, so the links move with it. ## contrib/postgres_fdw/connection.c - `pgfdw_inval_callback`, [connection.c:1295](https://github.com/postgres/postgres/blob/REL_18_3/contrib/postgres_fdw/connection.c#L1295) - [How PostgreSQL tells every connection its cache is stale: Keeping your own cache honest](https://sudohulk.com/writing/postgres-cache-invalidation#keeping-your-own-cache-honest) - [How PostgreSQL tells every connection its cache is stale: Dig deeper](https://sudohulk.com/writing/postgres-cache-invalidation#dig-deeper), a code trail ## contrib/postgres_fdw/shippable.c - `InvalidateShippableCacheCallback`, [shippable.c:64](https://github.com/postgres/postgres/blob/REL_18_3/contrib/postgres_fdw/shippable.c#L64) - [How PostgreSQL tells every connection its cache is stale: Keeping your own cache honest](https://sudohulk.com/writing/postgres-cache-invalidation#keeping-your-own-cache-honest) ## src/backend/access/transam/xact.c - `AtStart_Cache`, [xact.c:1166](https://github.com/postgres/postgres/blob/REL_18_3/src/backend/access/transam/xact.c#L1166) - [How PostgreSQL tells every connection its cache is stale: Dig deeper](https://sudohulk.com/writing/postgres-cache-invalidation#dig-deeper), a code trail - `CommitTransaction`, [xact.c:2227](https://github.com/postgres/postgres/blob/REL_18_3/src/backend/access/transam/xact.c#L2227) - [How PostgreSQL tells every connection its cache is stale: Dig deeper](https://sudohulk.com/writing/postgres-cache-invalidation#dig-deeper), a code trail ## src/backend/storage/ipc/sinval.c - `ProcessCatchupInterrupt`, [sinval.c:173](https://github.com/postgres/postgres/blob/REL_18_3/src/backend/storage/ipc/sinval.c#L173) - [How PostgreSQL tells every connection its cache is stale: Dig deeper](https://sudohulk.com/writing/postgres-cache-invalidation#dig-deeper), a code trail - `ReceiveSharedInvalidMessages`, [sinval.c:68](https://github.com/postgres/postgres/blob/REL_18_3/src/backend/storage/ipc/sinval.c#L68) - [How PostgreSQL tells every connection its cache is stale: Reading the ring before trusting the cache](https://sudohulk.com/writing/postgres-cache-invalidation#reading-the-ring-before-trusting-the-cache) - [How PostgreSQL tells every connection its cache is stale: Dig deeper](https://sudohulk.com/writing/postgres-cache-invalidation#dig-deeper), a code trail ## src/backend/storage/ipc/sinvaladt.c - `SICleanupQueue`, [sinvaladt.c:576](https://github.com/postgres/postgres/blob/REL_18_3/src/backend/storage/ipc/sinvaladt.c#L576) - [How PostgreSQL tells every connection its cache is stale: When the ring fills up](https://sudohulk.com/writing/postgres-cache-invalidation#when-the-ring-fills-up) - [How PostgreSQL tells every connection its cache is stale: Dig deeper](https://sudohulk.com/writing/postgres-cache-invalidation#dig-deeper), a code trail - `SIGetDataEntries`, [sinvaladt.c:472](https://github.com/postgres/postgres/blob/REL_18_3/src/backend/storage/ipc/sinvaladt.c#L472) - [How PostgreSQL tells every connection its cache is stale: Reading the ring before trusting the cache](https://sudohulk.com/writing/postgres-cache-invalidation#reading-the-ring-before-trusting-the-cache) - [How PostgreSQL tells every connection its cache is stale: Dig deeper](https://sudohulk.com/writing/postgres-cache-invalidation#dig-deeper), a code trail - `SIInsertDataEntries`, [sinvaladt.c:369](https://github.com/postgres/postgres/blob/REL_18_3/src/backend/storage/ipc/sinvaladt.c#L369) - [How PostgreSQL tells every connection its cache is stale: The ring of messages](https://sudohulk.com/writing/postgres-cache-invalidation#the-ring-of-messages) - [How PostgreSQL tells every connection its cache is stale: Dig deeper](https://sudohulk.com/writing/postgres-cache-invalidation#dig-deeper), a code trail ## src/backend/storage/lmgr/lmgr.c - `LockRelationOid`, [lmgr.c:106](https://github.com/postgres/postgres/blob/REL_18_3/src/backend/storage/lmgr/lmgr.c#L106) - [How PostgreSQL tells every connection its cache is stale: Reading the ring before trusting the cache](https://sudohulk.com/writing/postgres-cache-invalidation#reading-the-ring-before-trusting-the-cache) - [How PostgreSQL tells every connection its cache is stale: Dig deeper](https://sudohulk.com/writing/postgres-cache-invalidation#dig-deeper), a code trail ## src/backend/utils/cache/inval.c - `AcceptInvalidationMessages`, [inval.c:929](https://github.com/postgres/postgres/blob/REL_18_3/src/backend/utils/cache/inval.c#L929) - [How PostgreSQL tells every connection its cache is stale: Reading the ring before trusting the cache](https://sudohulk.com/writing/postgres-cache-invalidation#reading-the-ring-before-trusting-the-cache) - [How PostgreSQL tells every connection its cache is stale: Dig deeper](https://sudohulk.com/writing/postgres-cache-invalidation#dig-deeper), a code trail - `AtEOXact_Inval`, [inval.c:1198](https://github.com/postgres/postgres/blob/REL_18_3/src/backend/utils/cache/inval.c#L1198) - [How PostgreSQL tells every connection its cache is stale: Collecting changes until commit](https://sudohulk.com/writing/postgres-cache-invalidation#collecting-changes-until-commit) - [How PostgreSQL tells every connection its cache is stale: Dig deeper](https://sudohulk.com/writing/postgres-cache-invalidation#dig-deeper), a code trail - `CacheRegisterRelcacheCallback`, [inval.c:1857](https://github.com/postgres/postgres/blob/REL_18_3/src/backend/utils/cache/inval.c#L1857) - [How PostgreSQL tells every connection its cache is stale: Keeping your own cache honest](https://sudohulk.com/writing/postgres-cache-invalidation#keeping-your-own-cache-honest) - [How PostgreSQL tells every connection its cache is stale: Dig deeper](https://sudohulk.com/writing/postgres-cache-invalidation#dig-deeper), a code trail - `CacheRegisterSyscacheCallback`, [inval.c:1815](https://github.com/postgres/postgres/blob/REL_18_3/src/backend/utils/cache/inval.c#L1815) - [How PostgreSQL tells every connection its cache is stale: Keeping your own cache honest](https://sudohulk.com/writing/postgres-cache-invalidation#keeping-your-own-cache-honest) - [How PostgreSQL tells every connection its cache is stale: Dig deeper](https://sudohulk.com/writing/postgres-cache-invalidation#dig-deeper), a code trail - `CommandEndInvalidationMessages`, [inval.c:1408](https://github.com/postgres/postgres/blob/REL_18_3/src/backend/utils/cache/inval.c#L1408) - [How PostgreSQL tells every connection its cache is stale: Collecting changes until commit](https://sudohulk.com/writing/postgres-cache-invalidation#collecting-changes-until-commit) - [How PostgreSQL tells every connection its cache is stale: Dig deeper](https://sudohulk.com/writing/postgres-cache-invalidation#dig-deeper), a code trail - `InvalidateSystemCachesExtended`, [inval.c:784](https://github.com/postgres/postgres/blob/REL_18_3/src/backend/utils/cache/inval.c#L784) - [How PostgreSQL tells every connection its cache is stale: When the ring fills up](https://sudohulk.com/writing/postgres-cache-invalidation#when-the-ring-fills-up) - [How PostgreSQL tells every connection its cache is stale: Dig deeper](https://sudohulk.com/writing/postgres-cache-invalidation#dig-deeper), a code trail