Try row-by-row decompression if we consider startup cost - #9732
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…compression transparent_decompression_ordered_index constraint_exclusion_prepared ordered_append_join transparent_decompress_chunk
…ompression transparent_decompression_ordered_index constraint_exclusion_prepared ordered_append_join transparent_decompress_chunk
…ompression transparent_decompression_ordered_index constraint_exclusion_prepared ordered_append_join transparent_decompress_chunk
akuzm
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May 19, 2026
| Sort Key: d.device_id | ||
| -> Custom Scan (ColumnarScan) on _hyper_11_26_chunk d_1 (actual rows=3600.00 loops=1) | ||
| -> Index Scan using compress_hyper_12_29_chunk_device_id_device_id_peer__ts_met_idx on compress_hyper_12_29_chunk (actual rows=5.00 loops=1) | ||
| -> Sort (actual rows=5.00 loops=1) |
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This change looks confusing, so some explanation: the previous "Index Scan + bulk decompression" survived based on the startup cost there, the full cost is just slightly higher than sort. Now we have "Index Scan + row-by-row decompression", which has even better startup cost, but much worse total cost, so it first outcompetes the bulk path on startup cost, and then itself loses on total cost.
akuzm
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May 20, 2026
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May 20, 2026 09:45
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@Poroma-Banerjee, @natalya-aksman: please review this pull request.
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natalya-aksman
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May 20, 2026
…compression transparent_decompression_ordered_index constraint_exclusion_prepared ordered_append_join transparent_decompress_chunk
…ompression transparent_decompression_ordered_index constraint_exclusion_prepared ordered_append_join transparent_decompress_chunk
…ompression transparent_decompression_ordered_index constraint_exclusion_prepared ordered_append_join transparent_decompress_chunk
…dagg transparent_decompression transparent_decompression_ordered_index constraint_exclusion_prepared ordered_append_join transparent_decompress_chunk
dbeck
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Jun 8, 2026
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Jul 28, 2026
## 2.29.0 (2026-07-28) This release contains performance improvements and bug fixes since the 2.28.3 release. We recommend that you upgrade at the next available opportunity. **Release Highlights** * **Chunk exclusion for DML operations** drastically improves the performance of `UPDATE` and `DELETE` statements on hypertables. By acquiring exclusive locks only on the specific chunks being modified rather than the entire hypertable, this enhancement eliminates massive lock contention and keeps high-concurrency workloads running smoothly without unnecessary slowdowns. * Intelligent **row-by-row decompression** enables the query planner to decompress data row-by-row rather than in large batches when an operation prioritizes a fast initial response (such as queries with `LIMIT` clauses). This dramatically reduces memory overhead and query latency, ensuring lightning-fast performance when you only need to retrieve a small subset of records from your compressed hypertables. **Important: PostgreSQL 15 Support Removed** TimescaleDB 2.29.0 removes support for PostgreSQL 15. This release supports PostgreSQL 16, 17, and 18. If you are still running PostgreSQL 15, upgrade PostgreSQL before upgrading to TimescaleDB 2.29.0. **Backward-Incompatible Changes** * [#10041](#10041) Remove support for PostgreSQL 15 **Features** * [#9315](#9315) Speed up `DML` operations on hypertables by using the optimized TimescaleDB hypertable expansion code instead of the generic PostgreSQL inheritance hierarchy expansion * [#9534](#9534) Speed up expression evaluation in the columnar pipeline by caching common subexpressions * [#9684](#9684) Add `_timescaledb_functions.decompress_batch()` SQL function * [#9732](#9732) Speed up some queries with small `LIMIT` by switching to row-by-row query execution pipeline * [#9917](#9917) Decompress less data in `DML` on compressed hypertables by accounting for prepared statement parameters * [#9957](#9957) Add `compact_chunk()` function * [#10048](#10048) Support concurrent refresh policies on hierarchical continuous aggregates * [#10081](#10081) Add `samplerate` argument to `_timescaledb_functions.estimate_uncompressed_size()` * [#10100](#10100) Skip classifying compressed relations to speed up planning * [#10118](#10118) Don't track compressed relations as separate chunk * [#10119](#10119) Reduce memory usage of `INSERT` queries using direct compress and spanning multiple chunks * [#10163](#10163) Add a compaction policy for unordered chunks * [#10204](#10204) Don't create separate hypertable catalog entry for hypertables with compression * [#10217](#10217) Initial placeholder version of granular refresh API * [#10225](#10225) Add `config_merge` parameter to `alter_job()` for merging `jsonb` into the existing job configuration * [#10226](#10226) Add `recompress_unordered` columnstore policy option * [#10231](#10231) Use `regclass` for storing relation reference in chunk table * [#10237](#10237) Add helper functions for decoding hypertable status * [#10240](#10240) Add the `tsdb.direct_compress` storage parameter that allows enabling direct compress for a given hypertable independent of global settings * [#10266](#10266) Add `max_batches` to `compact_chunk()` * [#10299](#10299) Add `continuous_aggs_tenant_tracking` and `hypertable_cagg_settings` catalogs **Bugfixes** * [#10013](#10013) Make ownership error messages on continuous aggregates consistent * [#10052](#10052) Result of `MIN` / `MAX` aggregate functions in columnar aggregation pipeline possibly inconsistent with plain PostgreSQL result * [#10071](#10071) Prune the real-time branch of hierarchical continuous aggregates at any nesting depth * [#10143](#10143) Fix division by zero when planning `time_bucket` with zero width * [#10199](#10199) Fix `initial_start` handling in `build_job_info` * [#10213](#10213) Cache sort pathkeys per hypertable * [#10221](#10221) Fix incremental refresh skipping the last bucket * [#10278](#10278) Drop `job_errors` view in `bgw_job_stat_history` migration * [#10280](#10280) `RETURNING` clause returned no rows for `INSERT` using direct compress * [#10281](#10281) Disable direct compress when the destination table has an exclusion constraint so the constraint is still enforced * [#10282](#10282) Only count directly compressed rows toward the command tag when the `INSERT` sets it * [#10286](#10286) Propagate `VACUUM` on a chunk to the compressed relation when running on the chunk directly * [#10302](#10302) Fix useless-join removal and self-join elimination for hypertables * [#10313](#10313) Allow running `ALTER EXTENSION timescaledb UPDATE` inside a transaction block * [#10315](#10315) Fix overlap detection with running max * [#10324](#10324) Fix stale index entries after `rebuild_sparse_index()` on compressed chunks **GUCs** * `timescaledb.enable_hypertable_expansion_for_dml`: allow using the optimized TimescaleDB hypertable expansion code for `UPDATE` and `DELETE` instead of the generic PostgreSQL inheritance hierarchy expansion. On by default. **Thanks** * @FrancescEthon and @ManuelEthon for reporting the issue * @h0rn3t for reporting a problem with `VACUUM` not propagating to the compressed relation * @MaximeEthon for reporting an issue with prepared statement parameters in DML decompression * @proddata for reporting a problem when upgrading from 2.15.3 to 2.28.2 * @tureba for reporting and fixing stale sparse-index entries after rebuild * @viniciusrsouza for reporting an issue with hierarchical continuous aggregates
svenklemm
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Jul 28, 2026
This release contains performance improvements and bug fixes since the 2.28.3 release. We recommend that you upgrade at the next available opportunity. **Release Highlights** * **Chunk exclusion for DML operations** drastically improves the performance of `UPDATE` and `DELETE` statements on hypertables. By acquiring exclusive locks only on the specific chunks being modified rather than the entire hypertable, this enhancement eliminates massive lock contention and keeps high-concurrency workloads running smoothly without unnecessary slowdowns. * Intelligent **row-by-row decompression** enables the query planner to decompress data row-by-row rather than in large batches when an operation prioritizes a fast initial response (such as queries with `LIMIT` clauses). This dramatically reduces memory overhead and query latency, ensuring lightning-fast performance when you only need to retrieve a small subset of records from your compressed hypertables. **Important: PostgreSQL 15 Support Removed** TimescaleDB 2.29.0 removes support for PostgreSQL 15. This release supports PostgreSQL 16, 17, and 18. If you are still running PostgreSQL 15, upgrade PostgreSQL before upgrading to TimescaleDB 2.29.0. **Backward-Incompatible Changes** * [#10041](#10041) Remove support for PostgreSQL 15 **Features** * [#9315](#9315) Speed up `DML` operations on hypertables by using the optimized TimescaleDB hypertable expansion code instead of the generic PostgreSQL inheritance hierarchy expansion * [#9534](#9534) Speed up expression evaluation in the columnar pipeline by caching common subexpressions * [#9684](#9684) Add `_timescaledb_functions.decompress_batch()` SQL function * [#9732](#9732) Speed up some queries with small `LIMIT` by switching to row-by-row query execution pipeline * [#9917](#9917) Decompress less data in `DML` on compressed hypertables by accounting for prepared statement parameters * [#9957](#9957) Add `compact_chunk()` function * [#10048](#10048) Support concurrent refresh policies on hierarchical continuous aggregates * [#10081](#10081) Add `samplerate` argument to `_timescaledb_functions.estimate_uncompressed_size()` * [#10100](#10100) Skip classifying compressed relations to speed up planning * [#10118](#10118) Don't track compressed relations as separate chunk * [#10119](#10119) Reduce memory usage of `INSERT` queries using direct compress and spanning multiple chunks * [#10163](#10163) Add a compaction policy for unordered chunks * [#10204](#10204) Don't create separate hypertable catalog entry for hypertables with compression * [#10217](#10217) Initial placeholder version of granular refresh API * [#10225](#10225) Add `config_merge` parameter to `alter_job()` for merging `jsonb` into the existing job configuration * [#10226](#10226) Add `recompress_unordered` columnstore policy option * [#10231](#10231) Use `regclass` for storing relation reference in chunk table * [#10237](#10237) Add helper functions for decoding hypertable status * [#10240](#10240) Add the `tsdb.direct_compress` storage parameter that allows enabling direct compress for a given hypertable independent of global settings * [#10266](#10266) Add `max_batches` to `compact_chunk()` * [#10299](#10299) Add `continuous_aggs_tenant_tracking` and `hypertable_cagg_settings` catalogs **Bugfixes** * [#10013](#10013) Make ownership error messages on continuous aggregates consistent * [#10052](#10052) Result of `MIN` / `MAX` aggregate functions in columnar aggregation pipeline possibly inconsistent with plain PostgreSQL result * [#10071](#10071) Prune the real-time branch of hierarchical continuous aggregates at any nesting depth * [#10143](#10143) Fix division by zero when planning `time_bucket` with zero width * [#10199](#10199) Fix `initial_start` handling in `build_job_info` * [#10213](#10213) Cache sort pathkeys per hypertable * [#10221](#10221) Fix incremental refresh skipping the last bucket * [#10278](#10278) Drop `job_errors` view in `bgw_job_stat_history` migration * [#10280](#10280) `RETURNING` clause returned no rows for `INSERT` using direct compress * [#10281](#10281) Disable direct compress when the destination table has an exclusion constraint so the constraint is still enforced * [#10282](#10282) Only count directly compressed rows toward the command tag when the `INSERT` sets it * [#10286](#10286) Propagate `VACUUM` on a chunk to the compressed relation when running on the chunk directly * [#10302](#10302) Fix useless-join removal and self-join elimination for hypertables * [#10313](#10313) Allow running `ALTER EXTENSION timescaledb UPDATE` inside a transaction block * [#10315](#10315) Fix overlap detection with running max * [#10324](#10324) Fix stale index entries after `rebuild_sparse_index()` on compressed chunks **GUCs** * `timescaledb.enable_hypertable_expansion_for_dml`: allow using the optimized TimescaleDB hypertable expansion code for `UPDATE` and `DELETE` instead of the generic PostgreSQL inheritance hierarchy expansion. On by default. **Thanks** * @FrancescEthon and @ManuelEthon for reporting an issue with incremental refresh skipping the last bucket * @h0rn3t for reporting a problem with `VACUUM` not propagating to the * @igor2x for reporting an issue with locking during DML statements on hypertables compressed relation * @MaximeEthon for reporting an issue with prepared statement parameters in DML decompression * @proddata for reporting a problem when upgrading from 2.15.3 to 2.28.2 * @tureba for reporting and fixing stale sparse-index entries after rebuild * @viniciusrsouza for reporting an issue with hierarchical continuous aggregates
surister
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Jul 28, 2026
This release contains performance improvements and bug fixes since the 2.28.3 release. We recommend that you upgrade at the next available opportunity. **Release Highlights** * **Chunk exclusion for DML operations** drastically improves the performance of `UPDATE` and `DELETE` statements on hypertables. By acquiring exclusive locks only on the specific chunks being modified rather than the entire hypertable, this enhancement eliminates massive lock contention and keeps high-concurrency workloads running smoothly without unnecessary slowdowns. * Intelligent **row-by-row decompression** enables the query planner to decompress data row-by-row rather than in large batches when an operation prioritizes a fast initial response (such as queries with `LIMIT` clauses). This dramatically reduces memory overhead and query latency, ensuring lightning-fast performance when you only need to retrieve a small subset of records from your compressed hypertables. **Important: PostgreSQL 15 Support Removed** TimescaleDB 2.29.0 removes support for PostgreSQL 15. This release supports PostgreSQL 16, 17, and 18. If you are still running PostgreSQL 15, upgrade PostgreSQL before upgrading to TimescaleDB 2.29.0. **Backward-Incompatible Changes** * [timescale#10041](timescale#10041) Remove support for PostgreSQL 15 **Features** * [timescale#9315](timescale#9315) Speed up `DML` operations on hypertables by using the optimized TimescaleDB hypertable expansion code instead of the generic PostgreSQL inheritance hierarchy expansion * [timescale#9534](timescale#9534) Speed up expression evaluation in the columnar pipeline by caching common subexpressions * [timescale#9684](timescale#9684) Add `_timescaledb_functions.decompress_batch()` SQL function * [timescale#9732](timescale#9732) Speed up some queries with small `LIMIT` by switching to row-by-row query execution pipeline * [timescale#9917](timescale#9917) Decompress less data in `DML` on compressed hypertables by accounting for prepared statement parameters * [timescale#9957](timescale#9957) Add `compact_chunk()` function * [timescale#10048](timescale#10048) Support concurrent refresh policies on hierarchical continuous aggregates * [timescale#10081](timescale#10081) Add `samplerate` argument to `_timescaledb_functions.estimate_uncompressed_size()` * [timescale#10100](timescale#10100) Skip classifying compressed relations to speed up planning * [timescale#10118](timescale#10118) Don't track compressed relations as separate chunk * [timescale#10119](timescale#10119) Reduce memory usage of `INSERT` queries using direct compress and spanning multiple chunks * [timescale#10163](timescale#10163) Add a compaction policy for unordered chunks * [timescale#10204](timescale#10204) Don't create separate hypertable catalog entry for hypertables with compression * [timescale#10217](timescale#10217) Initial placeholder version of granular refresh API * [timescale#10225](timescale#10225) Add `config_merge` parameter to `alter_job()` for merging `jsonb` into the existing job configuration * [timescale#10226](timescale#10226) Add `recompress_unordered` columnstore policy option * [timescale#10231](timescale#10231) Use `regclass` for storing relation reference in chunk table * [timescale#10237](timescale#10237) Add helper functions for decoding hypertable status * [timescale#10240](timescale#10240) Add the `tsdb.direct_compress` storage parameter that allows enabling direct compress for a given hypertable independent of global settings * [timescale#10266](timescale#10266) Add `max_batches` to `compact_chunk()` * [timescale#10299](timescale#10299) Add `continuous_aggs_tenant_tracking` and `hypertable_cagg_settings` catalogs **Bugfixes** * [timescale#10013](timescale#10013) Make ownership error messages on continuous aggregates consistent * [timescale#10052](timescale#10052) Result of `MIN` / `MAX` aggregate functions in columnar aggregation pipeline possibly inconsistent with plain PostgreSQL result * [timescale#10071](timescale#10071) Prune the real-time branch of hierarchical continuous aggregates at any nesting depth * [timescale#10143](timescale#10143) Fix division by zero when planning `time_bucket` with zero width * [timescale#10199](timescale#10199) Fix `initial_start` handling in `build_job_info` * [timescale#10213](timescale#10213) Cache sort pathkeys per hypertable * [timescale#10221](timescale#10221) Fix incremental refresh skipping the last bucket * [timescale#10278](timescale#10278) Drop `job_errors` view in `bgw_job_stat_history` migration * [timescale#10280](timescale#10280) `RETURNING` clause returned no rows for `INSERT` using direct compress * [timescale#10281](timescale#10281) Disable direct compress when the destination table has an exclusion constraint so the constraint is still enforced * [timescale#10282](timescale#10282) Only count directly compressed rows toward the command tag when the `INSERT` sets it * [timescale#10286](timescale#10286) Propagate `VACUUM` on a chunk to the compressed relation when running on the chunk directly * [timescale#10302](timescale#10302) Fix useless-join removal and self-join elimination for hypertables * [timescale#10313](timescale#10313) Allow running `ALTER EXTENSION timescaledb UPDATE` inside a transaction block * [timescale#10315](timescale#10315) Fix overlap detection with running max * [timescale#10324](timescale#10324) Fix stale index entries after `rebuild_sparse_index()` on compressed chunks **GUCs** * `timescaledb.enable_hypertable_expansion_for_dml`: allow using the optimized TimescaleDB hypertable expansion code for `UPDATE` and `DELETE` instead of the generic PostgreSQL inheritance hierarchy expansion. On by default. **Thanks** * @FrancescEthon and @ManuelEthon for reporting an issue with incremental refresh skipping the last bucket * @h0rn3t for reporting a problem with `VACUUM` not propagating to the * @igor2x for reporting an issue with locking during DML statements on hypertables compressed relation * @MaximeEthon for reporting an issue with prepared statement parameters in DML decompression * @proddata for reporting a problem when upgrading from 2.15.3 to 2.28.2 * @tureba for reporting and fixing stale sparse-index entries after rebuild * @viniciusrsouza for reporting an issue with hierarchical continuous aggregates
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This only makes sense for paths that don't have sorting above decompression, and don't use the batch sorted merge.
Up to 7x improvement in tsbench (fast queries though): https://grafana.dev-us-east-1.ops.dev.timescale.com/d/fasYic_4z/compare-benchmark-runs?orgId=1&var-run1=5619&var-run2=5624&var-postgres=16&var-branch=All&var-threshold=0.02&var-use_historical_thresholds=true&var-threshold_expression=2.0%20%2A%20percentile_cont%280.90%29&var-exact_suite_version=true