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a51d21efbe
During chunk creation, the chunk's dimensional CHECK constraints are created via an "upcall" to PL/pgSQL code. However, creating dimensional constraints in PL/pgSQL code sometimes fails, especially during high-concurrency inserts, because PL/pgSQL code scans metadata using a snapshot that might not see the same metadata as the C code. As a result, chunk creation sometimes fail during constraint creation. To fix this issue, implement dimensional CHECK-constraint creation in C code. Other constraints (FK, PK, etc.) are still created via an upcall, but should probably also be rewritten in C. However, since these constraints don't depend on recently updated metadata, this is left to a future change. Fixes #5456
73 lines
2.4 KiB
PL/PgSQL
73 lines
2.4 KiB
PL/PgSQL
-- This file and its contents are licensed under the Apache License 2.0.
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-- Please see the included NOTICE for copyright information and
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-- LICENSE-APACHE for a copy of the license.
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-- This file contains functions associated with creating new
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-- hypertables.
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-- Outputs the create_hypertable command to recreate the given hypertable.
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--
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-- This is currently used internally for our single hypertable backup tool
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-- so that it knows how to restore the hypertable without user intervention.
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--
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-- It only works for hypertables with up to 2 dimensions.
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CREATE OR REPLACE FUNCTION _timescaledb_internal.get_create_command(
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table_name NAME
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)
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RETURNS TEXT LANGUAGE PLPGSQL VOLATILE AS
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$BODY$
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DECLARE
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h_id INTEGER;
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schema_name NAME;
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time_column NAME;
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time_interval BIGINT;
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space_column NAME;
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space_partitions INTEGER;
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dimension_cnt INTEGER;
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dimension_row record;
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ret TEXT;
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BEGIN
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SELECT h.id, h.schema_name
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FROM _timescaledb_catalog.hypertable AS h
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WHERE h.table_name = get_create_command.table_name
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INTO h_id, schema_name;
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IF h_id IS NULL THEN
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RAISE EXCEPTION 'hypertable "%" not found', table_name
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USING ERRCODE = 'TS101';
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END IF;
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SELECT COUNT(*)
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FROM _timescaledb_catalog.dimension d
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WHERE d.hypertable_id = h_id
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INTO STRICT dimension_cnt;
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IF dimension_cnt > 2 THEN
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RAISE EXCEPTION 'get_create_command only supports hypertables with up to 2 dimensions'
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USING ERRCODE = 'TS101';
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END IF;
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FOR dimension_row IN
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SELECT *
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FROM _timescaledb_catalog.dimension d
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WHERE d.hypertable_id = h_id
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LOOP
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IF dimension_row.interval_length IS NOT NULL THEN
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time_column := dimension_row.column_name;
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time_interval := dimension_row.interval_length;
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ELSIF dimension_row.num_slices IS NOT NULL THEN
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space_column := dimension_row.column_name;
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space_partitions := dimension_row.num_slices;
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END IF;
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END LOOP;
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ret := format($$SELECT create_hypertable('%I.%I', '%s'$$, schema_name, table_name, time_column);
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IF space_column IS NOT NULL THEN
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ret := ret || format($$, '%I', %s$$, space_column, space_partitions);
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END IF;
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ret := ret || format($$, chunk_time_interval => %s, create_default_indexes=>FALSE);$$, time_interval);
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RETURN ret;
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END
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$BODY$ SET search_path TO pg_catalog, pg_temp;
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