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Fix wording to reflect poor performance of initial query before optimization #20534

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Jun 27, 2025
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Fix wording to reflect poor performance of initial query before optimization #20534

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Add temp.md
qiancai Jun 20, 2025
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qiancai Jun 20, 2025
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Update explain-walkthrough.md
qiancai Jun 23, 2025
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2 changes: 1 addition & 1 deletion explain-walkthrough.md
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Expand Up @@ -67,7 +67,7 @@ EXPLAIN ANALYZE SELECT count(*) FROM trips WHERE start_date BETWEEN '2017-07-01
5 rows in set (1.03 sec)
```

执行以上示例查询耗时 `1.03` 秒，说明执行性能较为理想。
执行以上示例查询耗时 `1.03` 秒，说明执行性能不太理想。

以上 `EXPLAIN ANALYZE` 的结果中，`actRows` 表明一些 `estRows` 预估数不准确（预估返回 10000 行数据但实际返回 19117643 行）。`└─TableFullScan_18` 算子的 `operator info` 列 (`stats:pseudo`) 信息也表明该算子的预估数不准确。

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