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Check that compress_chunk_interval is used correctly #21

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mkindahl opened this issue Sep 12, 2023 · 1 comment
Open

Check that compress_chunk_interval is used correctly #21

mkindahl opened this issue Sep 12, 2023 · 1 comment
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enhancement New feature or request good first issue Good for newcomers

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@mkindahl
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mkindahl commented Sep 12, 2023 •
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If timescaledb.compress_chunk_interval is used the time column should be first in the timescaledb.compress_orderby list for the compression settings and also be marked as ascending.
@mkindahl mkindahl added enhancement New feature or request good first issue Good for newcomers labels Sep 12, 2023
@antekresic
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The technical reason is that we merge the chunks over time dimension so having compressed data not ordered over the time dimension primarily will create unordered compressed data.

The reason why we need ASC ordering is because we merge chunks in ascending order i.e. newer chunks get merged into older ones.

Both cases create unordered compressed chunks which need to be recompressed fully which is the cause of the performance hit.

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@mkindahl @antekresic