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Doc fix: edit some sentences

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ogorbacheva 2019-02-25 15:54:30 +03:00
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docs/en/query_language/select.md
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@ -50,9 +50,9 @@ The `SAMPLE` clause allows for approximated query processing. Approximated query
The features of data sampling are listed below:
- Data sampling is a determined mechanism. The result of the same `SELECT .. SAMPLE` query is always the same.
- Data sampling is a deterministic mechanism. The result of the same `SELECT .. SAMPLE` query is always the same.
- Sampling works consistently for different tables. For tables with a single sampling key, a sample with the same coefficient always selects the same subset of possible data. For example, a sample of user IDs takes rows with the same subset of all the possible user IDs from different tables. This allows using the sample in subqueries in the `IN` clause, as well as for manually correlating results of different queries with samples.
- Sampling allows reading fewer data from a disk. Note that for this you must specify the sampling key correctly. For more details see [Creating a MergeTree Table](../operations/table_engines/mergetree.md#table_engine-mergetree-creating-a-table).
- Sampling allows reading less data from a disk. Note that for this you must specify the sampling key correctly. For more details see [Creating a MergeTree Table](../operations/table_engines/mergetree.md#table_engine-mergetree-creating-a-table).
The `SAMPLE` clause can be specified in several ways: