Add snapshot-aware catalog lookup SQL functions#9693
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Introduce four _timescaledb_functions.* lookups that resolve TimescaleDB catalog entries against the active snapshot: chunk_id_by_name(schema name, table name) -> int4 compressed_chunk_parent_id(int4) -> int4 chunk_hypertable_id(int4) -> int4 hypertable_id_to_relid(int4) -> regclass Each function reads GetActiveSnapshot() and passes it explicitly into the catalog scan rather than relying on the scanner's default of SnapshotSelf. Callers that need a non-default snapshot -- e.g. a custom logical decoding plugin running against a HistoricSnapshot -- push it before invoking: PushActiveSnapshot(snapshot); /* DirectFunctionCall ... */ PopActiveSnapshot(); From an ordinary SQL session the executor's transaction snapshot is in effect, so the functions also work for ad-hoc use. All four return NULL on miss rather than erroring, so callers can skip rows that don't (yet) resolve.
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@pnthao, @antekresic: please review this pull request.
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Introduce four snapshot-aware _timescaledb_functions.* lookup functions that resolve TimescaleDB catalog entries against the active snapshot:
chunk_id_by_name(schema name, table name) -> int4compressed_chunk_parent_id(int4) -> int4chunk_hypertable_id(int4) -> int4hypertable_relid_by_id(int4) -> regclassEach function reads
GetActiveSnapshot()and passes it explicitly into the catalog scan rather than relying on the scanner's default ofSnapshotSelf. Callers that need a non-default snapshot -- e.g. a custom logical decoding plugin running against a HistoricSnapshot -- push it before invoking:From an ordinary SQL session the executor's transaction snapshot is in effect, so the functions also work for ad-hoc use. All four return NULL on miss rather than erroring, so callers can skip rows that don't (yet) resolve.
Follow-up for #9684