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Preview Sql.En

docs/document/content/user-manual/shardingsphere-proxy/distsql/syntax/rul/preview-sql.en.md

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+++ title = "PREVIEW SQL" weight = 3 +++

Description

The PREVIEW SQL syntax is used to preview SQL execution plan.

Syntax

{{< tabs >}} {{% tab name="Grammar" %}}

sql
PreviewSql ::=
  'PREVIEW' sqlStatement

{{% /tab %}} {{% tab name="Railroad diagram" %}}

<iframe frameborder="0" name="diagram" id="diagram" width="100%" height="100%"></iframe> {{% /tab %}} {{< /tabs >}}

Return Value Description

ColumnDescription
data_source_namestorage unit name
actual_sqlactual excute SQL statement

Example

  • Preview SQL execution plan
sql
PREVIEW SELECT * FROM t_order;
sql
mysql> PREVIEW SELECT * FROM t_order;
+------------------+-----------------------+
| data_source_name | actual_sql            |
+------------------+-----------------------+
| su_1             | SELECT * FROM t_order |
+------------------+-----------------------+
1 row in set (0.18 sec)

Reserved word

PREVIEW