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Add snapshot-aware catalog lookup SQL functions
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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12 files changed

Lines changed: 425 additions & 53 deletions

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‎.unreleased/pr_9693‎

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@@ -0,0 +1 @@
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Implements: #9693 Add snapshot-aware catalog lookup SQL functions

‎sql/chunk.sql‎

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@@ -36,6 +36,22 @@ AS $$ SELECT _timescaledb_functions.chunk_status_text(_timescaledb_functions.chu
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CREATE OR REPLACE FUNCTION _timescaledb_functions.chunk_id_from_relid(relid OID) RETURNS INTEGER
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AS '@MODULE_PATHNAME@', 'ts_chunk_id_from_relid' LANGUAGE C STABLE STRICT PARALLEL SAFE;
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-- Look up a chunk id by (schema_name, table_name) using the active snapshot.
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-- Intended for logical decoding plugins, which install a HistoricSnapshot via
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-- PushActiveSnapshot() before invoking. Returns NULL when no chunk matches.
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CREATE OR REPLACE FUNCTION _timescaledb_functions.chunk_id_by_name(schema_name NAME, table_name NAME) RETURNS INTEGER
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AS '@MODULE_PATHNAME@', 'ts_chunk_id_by_name' LANGUAGE C STABLE STRICT PARALLEL SAFE;
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-- Look up the parent (uncompressed) chunk id from a compressed chunk id, using
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-- the active snapshot. See chunk_id_by_name for snapshot semantics.
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CREATE OR REPLACE FUNCTION _timescaledb_functions.compressed_chunk_parent_id(compressed_chunk_id INTEGER) RETURNS INTEGER
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AS '@MODULE_PATHNAME@', 'ts_compressed_chunk_parent_id' LANGUAGE C STABLE STRICT PARALLEL SAFE;
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-- Look up the owning hypertable id of a chunk by chunk id, using the active
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-- snapshot. See chunk_id_by_name for snapshot semantics.
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CREATE OR REPLACE FUNCTION _timescaledb_functions.chunk_hypertable_id(chunk_id INTEGER) RETURNS INTEGER
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AS '@MODULE_PATHNAME@', 'ts_chunk_hypertable_id' LANGUAGE C STABLE STRICT PARALLEL SAFE;
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-- Show the definition of a chunk.
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CREATE OR REPLACE FUNCTION _timescaledb_functions.show_chunk(chunk REGCLASS)
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RETURNS TABLE(chunk_id INTEGER, hypertable_id INTEGER, schema_name NAME, table_name NAME, relkind "char", slices JSONB)

‎sql/hypertable.sql‎

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@@ -6,3 +6,10 @@ CREATE OR REPLACE FUNCTION @extschema@.set_integer_now_func(hypertable REGCLASS,
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AS '@MODULE_PATHNAME@', 'ts_hypertable_set_integer_now_func'
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LANGUAGE C VOLATILE STRICT;
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-- Look up a hypertable's relation Oid by its internal id, using the active
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-- snapshot. Intended for logical decoding plugins, which install a
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-- HistoricSnapshot via PushActiveSnapshot() before invoking. Returns NULL when
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-- no hypertable matches or its underlying relation cannot be resolved.
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CREATE OR REPLACE FUNCTION _timescaledb_functions.hypertable_relid_by_id(hypertable_id INTEGER) RETURNS REGCLASS
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AS '@MODULE_PATHNAME@', 'ts_hypertable_relid_by_id' LANGUAGE C STABLE STRICT PARALLEL SAFE;
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‎sql/updates/latest-dev.sql‎

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@@ -108,3 +108,18 @@ SET index = COALESCE(index, '[]'::jsonb) ||
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)
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WHERE cs.orderby IS NOT NULL;
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-- Snapshot-aware catalog lookup functions. Read GetActiveSnapshot() so callers
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-- (e.g. logical decoding plugins) that install a non-default snapshot via
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-- PushActiveSnapshot() can use them.
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CREATE OR REPLACE FUNCTION _timescaledb_functions.chunk_id_by_name(schema_name NAME, table_name NAME) RETURNS INTEGER
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AS '@MODULE_PATHNAME@', 'ts_update_placeholder' LANGUAGE C STABLE STRICT PARALLEL SAFE;
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CREATE OR REPLACE FUNCTION _timescaledb_functions.compressed_chunk_parent_id(compressed_chunk_id INTEGER) RETURNS INTEGER
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AS '@MODULE_PATHNAME@', 'ts_update_placeholder' LANGUAGE C STABLE STRICT PARALLEL SAFE;
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CREATE OR REPLACE FUNCTION _timescaledb_functions.chunk_hypertable_id(chunk_id INTEGER) RETURNS INTEGER
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AS '@MODULE_PATHNAME@', 'ts_update_placeholder' LANGUAGE C STABLE STRICT PARALLEL SAFE;
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CREATE OR REPLACE FUNCTION _timescaledb_functions.hypertable_relid_by_id(hypertable_id INTEGER) RETURNS REGCLASS
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AS '@MODULE_PATHNAME@', 'ts_update_placeholder' LANGUAGE C STABLE STRICT PARALLEL SAFE;
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‎sql/updates/reverse-dev.sql‎

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@@ -5,3 +5,8 @@ ALTER TABLE _timescaledb_catalog.chunk ADD CONSTRAINT chunk_compressed_chunk_id_
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DROP FUNCTION IF EXISTS _timescaledb_functions.bloom1_contains_any_hashes(_timescaledb_internal.bloom1, bigint[]);
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DROP FUNCTION IF EXISTS _timescaledb_functions.bloom1_hash(anyelement);
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DROP FUNCTION IF EXISTS _timescaledb_functions.chunk_id_by_name(NAME, NAME);
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DROP FUNCTION IF EXISTS _timescaledb_functions.compressed_chunk_parent_id(INTEGER);
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DROP FUNCTION IF EXISTS _timescaledb_functions.chunk_hypertable_id(INTEGER);
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DROP FUNCTION IF EXISTS _timescaledb_functions.hypertable_relid_by_id(INTEGER);

‎src/chunk.c‎

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@@ -49,6 +49,7 @@
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#include <utils/inval.h>
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#include <utils/lsyscache.h>
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#include <utils/palloc.h>
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#include <utils/snapmgr.h>
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#include <utils/syscache.h>
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#include <utils/timestamp.h>
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#include <utils/typcache.h>
@@ -94,6 +95,9 @@ TS_FUNCTION_INFO_V1(ts_chunk_drop_single_chunk);
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TS_FUNCTION_INFO_V1(ts_chunk_attach_osm_table_chunk);
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TS_FUNCTION_INFO_V1(ts_chunk_drop_osm_chunk);
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TS_FUNCTION_INFO_V1(ts_chunk_id_from_relid);
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TS_FUNCTION_INFO_V1(ts_chunk_id_by_name);
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TS_FUNCTION_INFO_V1(ts_compressed_chunk_parent_id);
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TS_FUNCTION_INFO_V1(ts_chunk_hypertable_id);
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TS_FUNCTION_INFO_V1(ts_chunk_show);
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TS_FUNCTION_INFO_V1(ts_chunk_create);
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TS_FUNCTION_INFO_V1(ts_chunk_status);
@@ -2896,6 +2900,145 @@ ts_chunk_id_from_relid(PG_FUNCTION_ARGS)
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PG_RETURN_INT32(last_id);
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}
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/*
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* Look up a chunk id by (schema, table) using the active snapshot.
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*
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* Reads the snapshot via GetActiveSnapshot() so a logical decoding plugin can
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* install a HistoricSnapshot via PushActiveSnapshot() before invoking. Returns
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* NULL when no matching chunk exists.
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*/
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Datum
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ts_chunk_id_by_name(PG_FUNCTION_ARGS)
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{
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Name schema = PG_GETARG_NAME(0);
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Name table = PG_GETARG_NAME(1);
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ScanIterator iterator = ts_scan_iterator_create(CHUNK, AccessShareLock, CurrentMemoryContext);
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int32 chunk_id = INVALID_CHUNK_ID;
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bool found = false;
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iterator.ctx.snapshot = GetActiveSnapshot();
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iterator.ctx.index = catalog_get_index(ts_catalog_get(), CHUNK, CHUNK_SCHEMA_NAME_INDEX);
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ts_scan_iterator_scan_key_init(&iterator,
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Anum_chunk_schema_name_idx_schema_name,
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BTEqualStrategyNumber,
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F_NAMEEQ,
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NameGetDatum(schema));
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ts_scan_iterator_scan_key_init(&iterator,
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Anum_chunk_schema_name_idx_table_name,
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BTEqualStrategyNumber,
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F_NAMEEQ,
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NameGetDatum(table));
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ts_scanner_foreach(&iterator)
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{
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bool isnull;
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Datum value = slot_getattr(iterator.tinfo->slot, Anum_chunk_id, &isnull);
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if (!isnull)
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{
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chunk_id = DatumGetInt32(value);
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found = true;
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}
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break;
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}
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ts_scan_iterator_close(&iterator);
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if (!found)
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{
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PG_RETURN_NULL();
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}
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PG_RETURN_INT32(chunk_id);
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}
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/*
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* Look up the parent (uncompressed) chunk id from a compressed chunk id, using
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* the active snapshot. See ts_chunk_id_by_name for snapshot semantics.
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*/
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Datum
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ts_compressed_chunk_parent_id(PG_FUNCTION_ARGS)
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{
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int32 compressed_chunk_id = PG_GETARG_INT32(0);
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ScanIterator iterator = ts_scan_iterator_create(CHUNK, AccessShareLock, CurrentMemoryContext);
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int32 chunk_id = INVALID_CHUNK_ID;
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bool found = false;
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iterator.ctx.snapshot = GetActiveSnapshot();
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iterator.ctx.index =
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catalog_get_index(ts_catalog_get(), CHUNK, CHUNK_COMPRESSED_CHUNK_ID_INDEX);
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ts_scan_iterator_scan_key_init(&iterator,
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Anum_chunk_compressed_chunk_id_idx_compressed_chunk_id,
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BTEqualStrategyNumber,
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F_INT4EQ,
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Int32GetDatum(compressed_chunk_id));
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ts_scanner_foreach(&iterator)
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{
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bool isnull;
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Datum value = slot_getattr(iterator.tinfo->slot, Anum_chunk_id, &isnull);
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if (!isnull)
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{
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chunk_id = DatumGetInt32(value);
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found = true;
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}
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break;
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}
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ts_scan_iterator_close(&iterator);
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2991+
if (!found)
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{
2993+
PG_RETURN_NULL();
2994+
}
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PG_RETURN_INT32(chunk_id);
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}
2998+
2999+
/*
3000+
* Look up the owning hypertable id of a chunk by chunk id, using the active
3001+
* snapshot. See ts_chunk_id_by_name for snapshot semantics.
3002+
*/
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Datum
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ts_chunk_hypertable_id(PG_FUNCTION_ARGS)
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{
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int32 chunk_id = PG_GETARG_INT32(0);
3007+
ScanIterator iterator = ts_scan_iterator_create(CHUNK, AccessShareLock, CurrentMemoryContext);
3008+
int32 hypertable_id = 0;
3009+
bool found = false;
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3011+
iterator.ctx.snapshot = GetActiveSnapshot();
3012+
iterator.ctx.index = catalog_get_index(ts_catalog_get(), CHUNK, CHUNK_ID_INDEX);
3013+
3014+
ts_scan_iterator_scan_key_init(&iterator,
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Anum_chunk_idx_id,
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BTEqualStrategyNumber,
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F_INT4EQ,
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Int32GetDatum(chunk_id));
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3020+
ts_scanner_foreach(&iterator)
3021+
{
3022+
bool isnull;
3023+
Datum value = slot_getattr(iterator.tinfo->slot, Anum_chunk_hypertable_id, &isnull);
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3025+
if (!isnull)
3026+
{
3027+
hypertable_id = DatumGetInt32(value);
3028+
found = true;
3029+
}
3030+
break;
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}
3032+
ts_scan_iterator_close(&iterator);
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3034+
if (!found)
3035+
{
3036+
PG_RETURN_NULL();
3037+
}
3038+
3039+
PG_RETURN_INT32(hypertable_id);
3040+
}
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bool
29003043
ts_chunk_exists_relid(Oid relid)
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{

‎src/hypertable.c‎

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@@ -382,6 +382,63 @@ ts_hypertable_id_to_relid(int32 hypertable_id, bool return_invalid)
382382
return relid;
383383
}
384384

385+
/*
386+
* Look up a hypertable's relation Oid by its internal id, using the active
387+
* snapshot.
388+
*
389+
* Reads the snapshot via GetActiveSnapshot() so a logical decoding plugin can
390+
* install a HistoricSnapshot via PushActiveSnapshot() before invoking. Returns
391+
* NULL when the hypertable does not exist or its underlying schema/relation
392+
* cannot be resolved against the same snapshot.
393+
*/
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TS_FUNCTION_INFO_V1(ts_hypertable_relid_by_id);
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Datum
396+
ts_hypertable_relid_by_id(PG_FUNCTION_ARGS)
397+
{
398+
int32 hypertable_id = PG_GETARG_INT32(0);
399+
ScanIterator iterator =
400+
ts_scan_iterator_create(HYPERTABLE, AccessShareLock, CurrentMemoryContext);
401+
Oid relid = InvalidOid;
402+
403+
iterator.ctx.snapshot = GetActiveSnapshot();
404+
iterator.ctx.index = catalog_get_index(ts_catalog_get(), HYPERTABLE, HYPERTABLE_ID_INDEX);
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406+
ts_scan_iterator_scan_key_init(&iterator,
407+
Anum_hypertable_pkey_idx_id,
408+
BTEqualStrategyNumber,
409+
F_INT4EQ,
410+
Int32GetDatum(hypertable_id));
411+
412+
ts_scanner_foreach(&iterator)
413+
{
414+
bool schema_isnull;
415+
bool table_isnull;
416+
Datum schema_datum =
417+
slot_getattr(iterator.tinfo->slot, Anum_hypertable_schema_name, &schema_isnull);
418+
Datum table_datum =
419+
slot_getattr(iterator.tinfo->slot, Anum_hypertable_table_name, &table_isnull);
420+
421+
if (!schema_isnull && !table_isnull)
422+
{
423+
Oid schema_oid = get_namespace_oid(NameStr(*DatumGetName(schema_datum)), true);
424+
425+
if (OidIsValid(schema_oid))
426+
{
427+
relid = get_relname_relid(NameStr(*DatumGetName(table_datum)), schema_oid);
428+
}
429+
}
430+
break;
431+
}
432+
ts_scan_iterator_close(&iterator);
433+
434+
if (!OidIsValid(relid))
435+
{
436+
PG_RETURN_NULL();
437+
}
438+
439+
PG_RETURN_OID(relid);
440+
}
441+
385442
int32
386443
ts_hypertable_relid_to_id(Oid relid)
387444
{

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