Prevent range overlap for chunks using constraint #6828
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| @@ -126,6 +126,7 @@ CREATE TABLE _timescaledb_catalog.dimension_slice ( | |||
| -- table constraints | |||
| CONSTRAINT dimension_slice_pkey PRIMARY KEY (id), | |||
| CONSTRAINT dimension_slice_dimension_id_range_start_range_end_key UNIQUE (dimension_id, range_start, range_end), | |||
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Arguably, this unique constraint could be dropped, its index though is still useful, and the UNIQUE isn't wrong, so we should just let it be?
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the unique is at least misleading so we should drop it, but we need to keep the index as that is used internally
sql/pre_install/tables.sql
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| @@ -126,6 +126,7 @@ CREATE TABLE _timescaledb_catalog.dimension_slice ( | |||
| -- table constraints | |||
| CONSTRAINT dimension_slice_pkey PRIMARY KEY (id), | |||
| CONSTRAINT dimension_slice_dimension_id_range_start_range_end_key UNIQUE (dimension_id, range_start, range_end), | |||
| CONSTRAINT dimension_slice_dimension_id_exclude EXCLUDE USING gist(int4range(dimension_id, dimension_id, '[]') WITH =, int8range(range_start, range_end, '[)') WITH &&), | |||
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Example usage here:
https://www.postgresql.org/docs/current/btree-gist.html#BTREE-GIST-EXAMPLE-USAGE
Using int4range(dimension_id, dimension_id, '[]') to not create a dependency on the btree_gist extension. This works just as well, with the downside of some more storage space required.
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This exclusion constraint prevents a single (time) value to exist in multiple dimension slices. We use `int4range(dimension_id, dimension_id, '[]')` as opposed to a direct compariso of `dimension_id` to not create a depenbency on `btree_gist`.
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Unfortunately it will not work because we use low level functions to update catalog tables and we only check for nulls, so no other constraints will be enforced when updating tsdb catalog tables. |
| ADD CONSTRAINT dimension_slice_dimension_id_exclude | ||
| EXCLUDE USING gist( | ||
| int4range(dimension_id, dimension_id, '[]') WITH =, | ||
| int8range(range_start, range_end, '[]') WITH && |
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| int8range(range_start, range_end, '[]') WITH && | |
| int8range(range_start, range_end, '[)') WITH && |
range_end should be exclusive
| @@ -126,6 +126,7 @@ CREATE TABLE _timescaledb_catalog.dimension_slice ( | |||
| -- table constraints | |||
| CONSTRAINT dimension_slice_pkey PRIMARY KEY (id), | |||
| CONSTRAINT dimension_slice_dimension_id_range_start_range_end_key UNIQUE (dimension_id, range_start, range_end), | |||
| CONSTRAINT dimension_slice_dimension_id_exclude EXCLUDE USING gist(int4range(dimension_id, dimension_id, '[]') WITH =, int8range(range_start, range_end, '[]') WITH &&), | |||
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| CONSTRAINT dimension_slice_dimension_id_exclude EXCLUDE USING gist(int4range(dimension_id, dimension_id, '[]') WITH =, int8range(range_start, range_end, '[]') WITH &&), | |
| CONSTRAINT dimension_slice_dimension_id_exclude EXCLUDE USING gist(int4range(dimension_id, dimension_id, '[]') WITH =, int8range(range_start, range_end, '[)') WITH &&), |
range_end should be exclusive
Constraints enforced by indexes will work |
This exclusion constraint prevents a single (time) value to exist in multiple dimension slices.