Align 2 prs from docs-cn (sql and planner) (#7005) (#7013)

pingcap · Nov 25, 2021 · c751190 · c751190
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diff --git a/optimizer-hints.md b/optimizer-hints.md
@@ -186,6 +186,16 @@ The `AGG_TO_COP()` hint tells the optimizer to push down the aggregate operation
 select /*+ AGG_TO_COP() */ sum(t1.a) from t t1;
 ```
 
+### LIMIT_TO_COP()
+
+The `LIMIT_TO_COP()` hint tells the optimizer to push down the `Limit` and `TopN` operators in the specified query block to the coprocessor. If the optimizer does not perform such an operation, it is recommended to use this hint. For example:
+
+{{< copyable "sql" >}}
+
+```sql
+SELECT /*+ LIMIT_TO_COP() */ * FROM t WHERE a = 1 AND b > 10 ORDER BY c LIMIT 1;
+```
+
 ### READ_FROM_STORAGE(TIFLASH[t1_name [, tl_name ...]], TIKV[t2_name [, tl_name ...]])
 
 The `READ_FROM_STORAGE(TIFLASH[t1_name [, tl_name ...]], TIKV[t2_name [, tl_name ...]])` hint tells the optimizer to read specific table(s) from specific storage engine(s). Currently, this hint supports two storage engine parameters - `TIKV` and `TIFLASH`. If a table has an alias, use the alias as the parameter of `READ_FROM_STORAGE()`; if the table does not has an alias, use the table's original name as the parameter. For example:

diff --git a/sql-statements/sql-statement-create-sequence.md b/sql-statements/sql-statement-create-sequence.md
@@ -47,7 +47,6 @@ CREATE [TEMPORARY] SEQUENCE [IF NOT EXISTS] sequence_name
     [ START [ WITH | = ] start ]
     [ CACHE [=] cache | NOCACHE | NO CACHE]
     [ CYCLE | NOCYCLE | NO CYCLE]
-    [ ORDER | NOORDER | NO ORDER]
     [table_options]
 ```
 
@@ -62,7 +61,6 @@ CREATE [TEMPORARY] SEQUENCE [IF NOT EXISTS] sequence_name
 | `START` | `MINVALUE` or `MAXVALUE`| Specifies the initial value of a sequence. When `INCREMENT` > `0`, the default value is `MINVALUE`. When `INCREMENT` < `0`, the default value is `MAXVALUE`. |
 | `CACHE` | `1000` | Specifies the local cache size of a sequence in TiDB. |
 | `CYCLE` | `NO CYCLE` | Specifies whether a sequence restarts from the minimum value (or maximum for the descending sequence). When `INCREMENT` > `0`, the default value is `MINVALUE`. When `INCREMENT` < `0`, the default value is `MAXVALUE`. |
-| `ORDER` | `NO ORDER` | TiDB currently does not support the `ORDER` option and provides only syntax compatibility for it. |
 
 ## `SEQUENCE` function