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Update releases/release-8.0.0.md
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Co-authored-by: joey-yez <[email protected]>
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qiancai and joey-yez authored Mar 27, 2024
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Expand Up @@ -106,7 +106,7 @@ Quick access: [Quick start](https://docs.pingcap.com/tidb/v8.0/quick-start-with-

In earlier versions of TiDB, the concurrency algorithm of the HashAgg operator does not support disk spill. If the execution plan of a SQL statement contains the concurrent HashAgg operator, all the data for that SQL statement can only be processed in memory. Consequently, TiDB has to process a large amount of data in memory. When the data size exceeds the memory limit, TiDB can only choose the non-concurrent algorithm, which does not leverage concurrency for performance improvement.

In v8.0.0, the concurrent HashAgg algorithm of TiDB supports disk spill. Under any concurrent conditions, the HashAgg operator can automatically trigger data spill based on memory usage, thus balancing performance and data throughput. Currently, as an experimental feature, TiDB introduces the `tidb_enable_concurrent_hashagg_spill` variable to control whether to enable the concurrent HashAgg algorithm that supports disk spill. When this variable is `ON`, it means enabled. This variable will be deprecated when the feature is generally available in a future release.
In v8.0.0, the concurrent HashAgg algorithm of TiDB supports disk spill. Under any concurrent conditions, the HashAgg operator can automatically trigger data spill based on memory usage, thus balancing performance and data throughput. Currently, as an experimental feature, TiDB introduces the `tidb_enable_concurrent_hashagg_spill` variable to control whether to enable the concurrent HashAgg algorithm that supports disk spill. When this variable is `ON`, it means enabled. This variable will be deprecated after the feature is generally available in a future release.

For more information, see [documentation](/system-variables.md#tidb_enable_concurrent_hashagg_spill-new-in-v800).

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