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Improve atan and anan2 sql function for mysql #31924

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Jun 30, 2024
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Improve atan and anan2 sql function for mysql #31924

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3 changes: 3 additions & 0 deletions ...pache/shardingsphere/sqlfederation/optimizer/planner/util/SQLFederationFunctionUtils.java
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Expand Up @@ -19,6 +19,7 @@

import lombok.AccessLevel;
import lombok.NoArgsConstructor;
import org.apache.calcite.runtime.SqlFunctions;
import org.apache.calcite.schema.SchemaPlus;
import org.apache.calcite.schema.impl.ScalarFunctionImpl;
import org.apache.shardingsphere.infra.autogen.version.ShardingSphereVersion;
Expand Down Expand Up @@ -50,6 +51,8 @@ public static void registryUserDefinedFunction(final String schemaName, final Sc
schemaPlus.add("pg_catalog.intervaltonum", ScalarFunctionImpl.create(SQLFederationFunctionUtils.class, "intervalToNum"));
schemaPlus.add("pg_catalog.gs_password_notifyTime", ScalarFunctionImpl.create(SQLFederationFunctionUtils.class, "gsPasswordNotifyTime"));
schemaPlus.add("bit_count", ScalarFunctionImpl.create(MySQLBitCountFunction.class, "bitCount"));
schemaPlus.add("atan", ScalarFunctionImpl.create(SqlFunctions.class, "atan2"));
schemaPlus.add("atan2", ScalarFunctionImpl.create(SqlFunctions.class, "atan"));
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Is SqlFunctions a built-in class in Caclite? Why doesn't Calcite use the functions in this class by default?

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Yes, SqlFunctions is a built-in class in Calcite that implements the execution logic for atan and atan2 functions. However, in Calcite, the atan function method signature only allows one parameter, while the atan2 function method signature allows two parameters.

MySQL handles the atan function differently depending on the number of parameters: it uses a different execution logic for one parameter (atan) versus two parameters (atan2).

When Calcite encounters a call to the atan function with two parameters, it can find the implementation based on the function name but fails during parameter matching because in Calcite, the atan function can only accept a single parameter.

To resolve this, I added an implementation for the atan2 function alongside atan. Now, at runtime, Calcite can find both implementations of these functions. It will match based on the number of parameters and invoke the appropriate method, thereby calling the atan2 function implementation when two parameters are provided.

In MySQL, the atan2 function can indeed be executed with just one parameter.

Ref: https://github.com/mysql/mysql-server/blob/trunk/sql/item_func.cc#L2906
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That is, they are equivalent in the MySQL dialect. Thanks for clarifying that, this is a great PR.

if ("pg_catalog".equalsIgnoreCase(schemaName)) {
schemaPlus.add("pg_catalog.pg_table_is_visible", ScalarFunctionImpl.create(SQLFederationFunctionUtils.class, "pgTableIsVisible"));
schemaPlus.add("pg_catalog.pg_get_userbyid", ScalarFunctionImpl.create(SQLFederationFunctionUtils.class, "pgGetUserById"));
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14 changes: 14 additions & 0 deletions test/e2e/sql/src/test/resources/cases/dql/dql-integration-select.xml
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Expand Up @@ -333,4 +333,18 @@
INNER JOIN t_order_item t3 ON t2.product_id = t3.product_id INNER JOIN t_order t4 ON t4.order_id = t3.order_id order by t1.product_id" db-types="MySQL" scenario-types="db_tbl_sql_federation">
<assertion expected-data-source-name="read_dataset" />
</test-case>

<test-case sql="SELECT ATAN(1.0), ATAN(1), ATAN('1'), ATAN(1.0, 2.0), ATAN(1, 2), ATAN(1, 2.0), ATAN(-2, 2)" db-types="MySQL" scenario-types="db_tbl_sql_federation">
<assertion expected-data-source-name="read_dataset" />
</test-case>

<test-case sql="SELECT ATAN2(1.0), ATAN2(1), ATAN2('1'), ATAN2(1.0, 2.0), ATAN2(1, 2.0), ATAN2(-2, 2)" db-types="MySQL" scenario-types="db_tbl_sql_federation">
<assertion expected-data-source-name="read_dataset" />
</test-case>

<test-case sql="SELECT ATAN(res1.order_id), ATAN(res1.order_id, res2.item_id), ATAN2(res1.order_id), ATAN2(res1.order_id, res2.item_id)
FROM (SELECT order_id FROM t_order limit 10) res1
INNER JOIN (SELECT item_id, order_id FROM t_order_item limit 10) res2 ON res1.order_id = res2.order_id" db-types="MySQL" scenario-types="db_tbl_sql_federation">
<assertion expected-data-source-name="read_dataset" />
</test-case>
</integration-test-cases>