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update engines/table-engines/mergetree-family/mergetree.md

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zxc111 2021-07-16 00:06:40 +08:00
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docs/en/engines/table-engines/mergetree-family/mergetree.md
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@ -76,7 +76,7 @@ For a description of parameters, see the [CREATE query description](../../../sql
- `SAMPLE BY` — An expression for sampling. Optional.
If a sampling expression is used, the primary key must contain it. Example: `SAMPLE BY intHash32(UserID) ORDER BY (CounterID, EventDate, intHash32(UserID))`.
If a sampling expression is used, the primary key must contain it. The result of sampling expression must be unsigned integer. Example: `SAMPLE BY intHash32(UserID) ORDER BY (CounterID, EventDate, intHash32(UserID))`.
- `TTL` — A list of rules specifying storage duration of rows and defining logic of automatic parts movement [between disks and volumes](#table_engine-mergetree-multiple-volumes). Optional.

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docs/en/operations/settings/merge-tree-settings.md
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@ -280,14 +280,14 @@ Default value: `0`.
## check_sample_column_is_correct {#check_sample_column_is_correct}
Enables to check column or column by hash for sampling is correct at creation table.
Enables to check column for sampling or sampling expression is correct at creation table.
Possible values:
- true — Check column for sampling is correct at creation table
- false — Check column for sampling is correct at creation table will be ignored.
- true — Check column or sampling expression is correct at creation table
- false — Check column or sampling expression is at creation table will be ignored.
Default value: `true`.
By default, the ClickHouse server check sampling condition at creation table. If you already had tables with incorrect sampling condition, set value `false` to make ClickHouse server do not raise exception when ClickHouse server is starting.
By default, the ClickHouse server check column for sampling or sampling expression at creation table. If you already had tables with incorrect sampling expression, set value `false` to make ClickHouse server do not raise exception when ClickHouse server is starting.
[Original article](https://clickhouse.tech/docs/en/operations/settings/merge_tree_settings/) <!--hide-->